mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
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35ce8ae9ae
Pull signal/exit/ptrace updates from Eric Biederman: "This set of changes deletes some dead code, makes a lot of cleanups which hopefully make the code easier to follow, and fixes bugs found along the way. The end-game which I have not yet reached yet is for fatal signals that generate coredumps to be short-circuit deliverable from complete_signal, for force_siginfo_to_task not to require changing userspace configured signal delivery state, and for the ptrace stops to always happen in locations where we can guarantee on all architectures that the all of the registers are saved and available on the stack. Removal of profile_task_ext, profile_munmap, and profile_handoff_task are the big successes for dead code removal this round. A bunch of small bug fixes are included, as most of the issues reported were small enough that they would not affect bisection so I simply added the fixes and did not fold the fixes into the changes they were fixing. There was a bug that broke coredumps piped to systemd-coredump. I dropped the change that caused that bug and replaced it entirely with something much more restrained. Unfortunately that required some rebasing. Some successes after this set of changes: There are few enough calls to do_exit to audit in a reasonable amount of time. The lifetime of struct kthread now matches the lifetime of struct task, and the pointer to struct kthread is no longer stored in set_child_tid. The flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is removed. Issues where task->exit_code was examined with signal->group_exit_code should been examined were fixed. There are several loosely related changes included because I am cleaning up and if I don't include them they will probably get lost. The original postings of these changes can be found at: https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org I trimmed back the last set of changes to only the obviously correct once. Simply because there was less time for review than I had hoped" * 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits) ptrace/m68k: Stop open coding ptrace_report_syscall ptrace: Remove unused regs argument from ptrace_report_syscall ptrace: Remove second setting of PT_SEIZED in ptrace_attach taskstats: Cleanup the use of task->exit_code exit: Use the correct exit_code in /proc/<pid>/stat exit: Fix the exit_code for wait_task_zombie exit: Coredumps reach do_group_exit exit: Remove profile_handoff_task exit: Remove profile_task_exit & profile_munmap signal: clean up kernel-doc comments signal: Remove the helper signal_group_exit signal: Rename group_exit_task group_exec_task coredump: Stop setting signal->group_exit_task signal: Remove SIGNAL_GROUP_COREDUMP signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process signal: Make coredump handling explicit in complete_signal signal: Have prepare_signal detect coredumps using signal->core_state signal: Have the oom killer detect coredumps using signal->core_state exit: Move force_uaccess back into do_exit exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit ...
3808 lines
102 KiB
C
3808 lines
102 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/mmap.c
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*
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* Written by obz.
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*
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* Address space accounting code <alan@lxorguk.ukuu.org.uk>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/mm.h>
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#include <linux/mm_inline.h>
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#include <linux/vmacache.h>
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#include <linux/shm.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/shmem_fs.h>
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#include <linux/profile.h>
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#include <linux/export.h>
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#include <linux/mount.h>
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#include <linux/mempolicy.h>
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#include <linux/rmap.h>
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#include <linux/mmu_notifier.h>
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#include <linux/mmdebug.h>
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#include <linux/perf_event.h>
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#include <linux/audit.h>
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#include <linux/khugepaged.h>
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#include <linux/uprobes.h>
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#include <linux/rbtree_augmented.h>
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#include <linux/notifier.h>
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#include <linux/memory.h>
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#include <linux/printk.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/moduleparam.h>
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#include <linux/pkeys.h>
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#include <linux/oom.h>
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#include <linux/sched/mm.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/tlb.h>
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#include <asm/mmu_context.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/mmap.h>
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#include "internal.h"
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#ifndef arch_mmap_check
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#define arch_mmap_check(addr, len, flags) (0)
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
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const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
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const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
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int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
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const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
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const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
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int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
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#endif
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static bool ignore_rlimit_data;
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core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
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static void unmap_region(struct mm_struct *mm,
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struct vm_area_struct *vma, struct vm_area_struct *prev,
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unsigned long start, unsigned long end);
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/* description of effects of mapping type and prot in current implementation.
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* this is due to the limited x86 page protection hardware. The expected
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* behavior is in parens:
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*
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* map_type prot
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* PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
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* MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
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* w: (no) no w: (no) no w: (yes) yes w: (no) no
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* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
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*
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* MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
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* w: (no) no w: (no) no w: (copy) copy w: (no) no
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* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
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*
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* On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
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* MAP_PRIVATE (with Enhanced PAN supported):
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* r: (no) no
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* w: (no) no
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* x: (yes) yes
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*/
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pgprot_t protection_map[16] __ro_after_init = {
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__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
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__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
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};
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#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
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static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
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{
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return prot;
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}
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#endif
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pgprot_t vm_get_page_prot(unsigned long vm_flags)
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{
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pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
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(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
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pgprot_val(arch_vm_get_page_prot(vm_flags)));
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return arch_filter_pgprot(ret);
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}
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EXPORT_SYMBOL(vm_get_page_prot);
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static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
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{
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return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
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}
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/* Update vma->vm_page_prot to reflect vma->vm_flags. */
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void vma_set_page_prot(struct vm_area_struct *vma)
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{
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unsigned long vm_flags = vma->vm_flags;
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pgprot_t vm_page_prot;
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vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
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if (vma_wants_writenotify(vma, vm_page_prot)) {
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vm_flags &= ~VM_SHARED;
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vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
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}
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/* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
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WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
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}
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/*
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* Requires inode->i_mapping->i_mmap_rwsem
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*/
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static void __remove_shared_vm_struct(struct vm_area_struct *vma,
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struct file *file, struct address_space *mapping)
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{
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if (vma->vm_flags & VM_SHARED)
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mapping_unmap_writable(mapping);
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flush_dcache_mmap_lock(mapping);
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vma_interval_tree_remove(vma, &mapping->i_mmap);
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flush_dcache_mmap_unlock(mapping);
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}
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/*
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* Unlink a file-based vm structure from its interval tree, to hide
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* vma from rmap and vmtruncate before freeing its page tables.
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*/
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void unlink_file_vma(struct vm_area_struct *vma)
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{
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struct file *file = vma->vm_file;
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if (file) {
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struct address_space *mapping = file->f_mapping;
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i_mmap_lock_write(mapping);
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__remove_shared_vm_struct(vma, file, mapping);
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i_mmap_unlock_write(mapping);
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}
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}
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/*
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* Close a vm structure and free it, returning the next.
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*/
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static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
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{
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struct vm_area_struct *next = vma->vm_next;
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might_sleep();
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if (vma->vm_ops && vma->vm_ops->close)
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vma->vm_ops->close(vma);
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if (vma->vm_file)
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fput(vma->vm_file);
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mpol_put(vma_policy(vma));
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vm_area_free(vma);
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return next;
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}
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static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
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struct list_head *uf);
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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
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unsigned long newbrk, oldbrk, origbrk;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *next;
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unsigned long min_brk;
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bool populate;
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bool downgraded = false;
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LIST_HEAD(uf);
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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origbrk = mm->brk;
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#ifdef CONFIG_COMPAT_BRK
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/*
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* CONFIG_COMPAT_BRK can still be overridden by setting
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* randomize_va_space to 2, which will still cause mm->start_brk
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* to be arbitrarily shifted
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*/
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if (current->brk_randomized)
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min_brk = mm->start_brk;
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else
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min_brk = mm->end_data;
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#else
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min_brk = mm->start_brk;
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#endif
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if (brk < min_brk)
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goto out;
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/*
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* Check against rlimit here. If this check is done later after the test
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* of oldbrk with newbrk then it can escape the test and let the data
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* segment grow beyond its set limit the in case where the limit is
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* not page aligned -Ram Gupta
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*/
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if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
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mm->end_data, mm->start_data))
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goto out;
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newbrk = PAGE_ALIGN(brk);
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oldbrk = PAGE_ALIGN(mm->brk);
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if (oldbrk == newbrk) {
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mm->brk = brk;
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goto success;
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}
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/*
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* Always allow shrinking brk.
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* __do_munmap() may downgrade mmap_lock to read.
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*/
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if (brk <= mm->brk) {
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int ret;
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/*
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* mm->brk must to be protected by write mmap_lock so update it
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* before downgrading mmap_lock. When __do_munmap() fails,
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* mm->brk will be restored from origbrk.
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*/
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mm->brk = brk;
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ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
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if (ret < 0) {
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mm->brk = origbrk;
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goto out;
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} else if (ret == 1) {
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downgraded = true;
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}
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goto success;
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}
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/* Check against existing mmap mappings. */
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next = find_vma(mm, oldbrk);
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if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
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goto out;
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/* Ok, looks good - let it rip. */
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if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
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goto out;
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mm->brk = brk;
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success:
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populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
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if (downgraded)
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mmap_read_unlock(mm);
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else
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mmap_write_unlock(mm);
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userfaultfd_unmap_complete(mm, &uf);
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if (populate)
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mm_populate(oldbrk, newbrk - oldbrk);
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return brk;
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out:
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mmap_write_unlock(mm);
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return origbrk;
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}
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static inline unsigned long vma_compute_gap(struct vm_area_struct *vma)
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{
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unsigned long gap, prev_end;
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/*
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* Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
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* allow two stack_guard_gaps between them here, and when choosing
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* an unmapped area; whereas when expanding we only require one.
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* That's a little inconsistent, but keeps the code here simpler.
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*/
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gap = vm_start_gap(vma);
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if (vma->vm_prev) {
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prev_end = vm_end_gap(vma->vm_prev);
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if (gap > prev_end)
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gap -= prev_end;
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else
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gap = 0;
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}
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return gap;
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}
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#ifdef CONFIG_DEBUG_VM_RB
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static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma)
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{
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unsigned long max = vma_compute_gap(vma), subtree_gap;
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if (vma->vm_rb.rb_left) {
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subtree_gap = rb_entry(vma->vm_rb.rb_left,
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struct vm_area_struct, vm_rb)->rb_subtree_gap;
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if (subtree_gap > max)
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max = subtree_gap;
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}
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if (vma->vm_rb.rb_right) {
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subtree_gap = rb_entry(vma->vm_rb.rb_right,
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struct vm_area_struct, vm_rb)->rb_subtree_gap;
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if (subtree_gap > max)
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max = subtree_gap;
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}
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return max;
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}
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static int browse_rb(struct mm_struct *mm)
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{
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struct rb_root *root = &mm->mm_rb;
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int i = 0, j, bug = 0;
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struct rb_node *nd, *pn = NULL;
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unsigned long prev = 0, pend = 0;
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for (nd = rb_first(root); nd; nd = rb_next(nd)) {
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struct vm_area_struct *vma;
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vma = rb_entry(nd, struct vm_area_struct, vm_rb);
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if (vma->vm_start < prev) {
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pr_emerg("vm_start %lx < prev %lx\n",
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vma->vm_start, prev);
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bug = 1;
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}
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if (vma->vm_start < pend) {
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pr_emerg("vm_start %lx < pend %lx\n",
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vma->vm_start, pend);
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bug = 1;
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}
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if (vma->vm_start > vma->vm_end) {
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pr_emerg("vm_start %lx > vm_end %lx\n",
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vma->vm_start, vma->vm_end);
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bug = 1;
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}
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spin_lock(&mm->page_table_lock);
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if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
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pr_emerg("free gap %lx, correct %lx\n",
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vma->rb_subtree_gap,
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vma_compute_subtree_gap(vma));
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bug = 1;
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}
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spin_unlock(&mm->page_table_lock);
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i++;
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pn = nd;
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prev = vma->vm_start;
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pend = vma->vm_end;
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}
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j = 0;
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for (nd = pn; nd; nd = rb_prev(nd))
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j++;
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if (i != j) {
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pr_emerg("backwards %d, forwards %d\n", j, i);
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bug = 1;
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}
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return bug ? -1 : i;
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}
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static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
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{
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struct rb_node *nd;
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for (nd = rb_first(root); nd; nd = rb_next(nd)) {
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struct vm_area_struct *vma;
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vma = rb_entry(nd, struct vm_area_struct, vm_rb);
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VM_BUG_ON_VMA(vma != ignore &&
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vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
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vma);
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}
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}
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static void validate_mm(struct mm_struct *mm)
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{
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int bug = 0;
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int i = 0;
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unsigned long highest_address = 0;
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struct vm_area_struct *vma = mm->mmap;
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while (vma) {
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struct anon_vma *anon_vma = vma->anon_vma;
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struct anon_vma_chain *avc;
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if (anon_vma) {
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anon_vma_lock_read(anon_vma);
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list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
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anon_vma_interval_tree_verify(avc);
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anon_vma_unlock_read(anon_vma);
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}
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highest_address = vm_end_gap(vma);
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vma = vma->vm_next;
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i++;
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}
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if (i != mm->map_count) {
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pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
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bug = 1;
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}
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if (highest_address != mm->highest_vm_end) {
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pr_emerg("mm->highest_vm_end %lx, found %lx\n",
|
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mm->highest_vm_end, highest_address);
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bug = 1;
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}
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i = browse_rb(mm);
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if (i != mm->map_count) {
|
|
if (i != -1)
|
|
pr_emerg("map_count %d rb %d\n", mm->map_count, i);
|
|
bug = 1;
|
|
}
|
|
VM_BUG_ON_MM(bug, mm);
|
|
}
|
|
#else
|
|
#define validate_mm_rb(root, ignore) do { } while (0)
|
|
#define validate_mm(mm) do { } while (0)
|
|
#endif
|
|
|
|
RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks,
|
|
struct vm_area_struct, vm_rb,
|
|
unsigned long, rb_subtree_gap, vma_compute_gap)
|
|
|
|
/*
|
|
* Update augmented rbtree rb_subtree_gap values after vma->vm_start or
|
|
* vma->vm_prev->vm_end values changed, without modifying the vma's position
|
|
* in the rbtree.
|
|
*/
|
|
static void vma_gap_update(struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* As it turns out, RB_DECLARE_CALLBACKS_MAX() already created
|
|
* a callback function that does exactly what we want.
|
|
*/
|
|
vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
|
|
}
|
|
|
|
static inline void vma_rb_insert(struct vm_area_struct *vma,
|
|
struct rb_root *root)
|
|
{
|
|
/* All rb_subtree_gap values must be consistent prior to insertion */
|
|
validate_mm_rb(root, NULL);
|
|
|
|
rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
|
|
}
|
|
|
|
static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
|
|
{
|
|
/*
|
|
* Note rb_erase_augmented is a fairly large inline function,
|
|
* so make sure we instantiate it only once with our desired
|
|
* augmented rbtree callbacks.
|
|
*/
|
|
rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
|
|
}
|
|
|
|
static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
|
|
struct rb_root *root,
|
|
struct vm_area_struct *ignore)
|
|
{
|
|
/*
|
|
* All rb_subtree_gap values must be consistent prior to erase,
|
|
* with the possible exception of
|
|
*
|
|
* a. the "next" vma being erased if next->vm_start was reduced in
|
|
* __vma_adjust() -> __vma_unlink()
|
|
* b. the vma being erased in detach_vmas_to_be_unmapped() ->
|
|
* vma_rb_erase()
|
|
*/
|
|
validate_mm_rb(root, ignore);
|
|
|
|
__vma_rb_erase(vma, root);
|
|
}
|
|
|
|
static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
|
|
struct rb_root *root)
|
|
{
|
|
vma_rb_erase_ignore(vma, root, vma);
|
|
}
|
|
|
|
/*
|
|
* vma has some anon_vma assigned, and is already inserted on that
|
|
* anon_vma's interval trees.
|
|
*
|
|
* Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
|
|
* vma must be removed from the anon_vma's interval trees using
|
|
* anon_vma_interval_tree_pre_update_vma().
|
|
*
|
|
* After the update, the vma will be reinserted using
|
|
* anon_vma_interval_tree_post_update_vma().
|
|
*
|
|
* The entire update must be protected by exclusive mmap_lock and by
|
|
* the root anon_vma's mutex.
|
|
*/
|
|
static inline void
|
|
anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma_chain *avc;
|
|
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
|
|
}
|
|
|
|
static inline void
|
|
anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma_chain *avc;
|
|
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
|
|
}
|
|
|
|
static int find_vma_links(struct mm_struct *mm, unsigned long addr,
|
|
unsigned long end, struct vm_area_struct **pprev,
|
|
struct rb_node ***rb_link, struct rb_node **rb_parent)
|
|
{
|
|
struct rb_node **__rb_link, *__rb_parent, *rb_prev;
|
|
|
|
mmap_assert_locked(mm);
|
|
__rb_link = &mm->mm_rb.rb_node;
|
|
rb_prev = __rb_parent = NULL;
|
|
|
|
while (*__rb_link) {
|
|
struct vm_area_struct *vma_tmp;
|
|
|
|
__rb_parent = *__rb_link;
|
|
vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
|
|
|
|
if (vma_tmp->vm_end > addr) {
|
|
/* Fail if an existing vma overlaps the area */
|
|
if (vma_tmp->vm_start < end)
|
|
return -ENOMEM;
|
|
__rb_link = &__rb_parent->rb_left;
|
|
} else {
|
|
rb_prev = __rb_parent;
|
|
__rb_link = &__rb_parent->rb_right;
|
|
}
|
|
}
|
|
|
|
*pprev = NULL;
|
|
if (rb_prev)
|
|
*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
|
|
*rb_link = __rb_link;
|
|
*rb_parent = __rb_parent;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* vma_next() - Get the next VMA.
|
|
* @mm: The mm_struct.
|
|
* @vma: The current vma.
|
|
*
|
|
* If @vma is NULL, return the first vma in the mm.
|
|
*
|
|
* Returns: The next VMA after @vma.
|
|
*/
|
|
static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
if (!vma)
|
|
return mm->mmap;
|
|
|
|
return vma->vm_next;
|
|
}
|
|
|
|
/*
|
|
* munmap_vma_range() - munmap VMAs that overlap a range.
|
|
* @mm: The mm struct
|
|
* @start: The start of the range.
|
|
* @len: The length of the range.
|
|
* @pprev: pointer to the pointer that will be set to previous vm_area_struct
|
|
* @rb_link: the rb_node
|
|
* @rb_parent: the parent rb_node
|
|
*
|
|
* Find all the vm_area_struct that overlap from @start to
|
|
* @end and munmap them. Set @pprev to the previous vm_area_struct.
|
|
*
|
|
* Returns: -ENOMEM on munmap failure or 0 on success.
|
|
*/
|
|
static inline int
|
|
munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,
|
|
struct vm_area_struct **pprev, struct rb_node ***link,
|
|
struct rb_node **parent, struct list_head *uf)
|
|
{
|
|
|
|
while (find_vma_links(mm, start, start + len, pprev, link, parent))
|
|
if (do_munmap(mm, start, len, uf))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
static unsigned long count_vma_pages_range(struct mm_struct *mm,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
unsigned long nr_pages = 0;
|
|
struct vm_area_struct *vma;
|
|
|
|
/* Find first overlapping mapping */
|
|
vma = find_vma_intersection(mm, addr, end);
|
|
if (!vma)
|
|
return 0;
|
|
|
|
nr_pages = (min(end, vma->vm_end) -
|
|
max(addr, vma->vm_start)) >> PAGE_SHIFT;
|
|
|
|
/* Iterate over the rest of the overlaps */
|
|
for (vma = vma->vm_next; vma; vma = vma->vm_next) {
|
|
unsigned long overlap_len;
|
|
|
|
if (vma->vm_start > end)
|
|
break;
|
|
|
|
overlap_len = min(end, vma->vm_end) - vma->vm_start;
|
|
nr_pages += overlap_len >> PAGE_SHIFT;
|
|
}
|
|
|
|
return nr_pages;
|
|
}
|
|
|
|
void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct rb_node **rb_link, struct rb_node *rb_parent)
|
|
{
|
|
/* Update tracking information for the gap following the new vma. */
|
|
if (vma->vm_next)
|
|
vma_gap_update(vma->vm_next);
|
|
else
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
|
|
/*
|
|
* vma->vm_prev wasn't known when we followed the rbtree to find the
|
|
* correct insertion point for that vma. As a result, we could not
|
|
* update the vma vm_rb parents rb_subtree_gap values on the way down.
|
|
* So, we first insert the vma with a zero rb_subtree_gap value
|
|
* (to be consistent with what we did on the way down), and then
|
|
* immediately update the gap to the correct value. Finally we
|
|
* rebalance the rbtree after all augmented values have been set.
|
|
*/
|
|
rb_link_node(&vma->vm_rb, rb_parent, rb_link);
|
|
vma->rb_subtree_gap = 0;
|
|
vma_gap_update(vma);
|
|
vma_rb_insert(vma, &mm->mm_rb);
|
|
}
|
|
|
|
static void __vma_link_file(struct vm_area_struct *vma)
|
|
{
|
|
struct file *file;
|
|
|
|
file = vma->vm_file;
|
|
if (file) {
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
if (vma->vm_flags & VM_SHARED)
|
|
mapping_allow_writable(mapping);
|
|
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_interval_tree_insert(vma, &mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
}
|
|
|
|
static void
|
|
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, struct rb_node **rb_link,
|
|
struct rb_node *rb_parent)
|
|
{
|
|
__vma_link_list(mm, vma, prev);
|
|
__vma_link_rb(mm, vma, rb_link, rb_parent);
|
|
}
|
|
|
|
static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, struct rb_node **rb_link,
|
|
struct rb_node *rb_parent)
|
|
{
|
|
struct address_space *mapping = NULL;
|
|
|
|
if (vma->vm_file) {
|
|
mapping = vma->vm_file->f_mapping;
|
|
i_mmap_lock_write(mapping);
|
|
}
|
|
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
__vma_link_file(vma);
|
|
|
|
if (mapping)
|
|
i_mmap_unlock_write(mapping);
|
|
|
|
mm->map_count++;
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* Helper for vma_adjust() in the split_vma insert case: insert a vma into the
|
|
* mm's list and rbtree. It has already been inserted into the interval tree.
|
|
*/
|
|
static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
|
|
if (find_vma_links(mm, vma->vm_start, vma->vm_end,
|
|
&prev, &rb_link, &rb_parent))
|
|
BUG();
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
mm->map_count++;
|
|
}
|
|
|
|
static __always_inline void __vma_unlink(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
struct vm_area_struct *ignore)
|
|
{
|
|
vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
|
|
__vma_unlink_list(mm, vma);
|
|
/* Kill the cache */
|
|
vmacache_invalidate(mm);
|
|
}
|
|
|
|
/*
|
|
* We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
|
|
* is already present in an i_mmap tree without adjusting the tree.
|
|
* The following helper function should be used when such adjustments
|
|
* are necessary. The "insert" vma (if any) is to be inserted
|
|
* before we drop the necessary locks.
|
|
*/
|
|
int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
|
|
struct vm_area_struct *expand)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
|
|
struct address_space *mapping = NULL;
|
|
struct rb_root_cached *root = NULL;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct file *file = vma->vm_file;
|
|
bool start_changed = false, end_changed = false;
|
|
long adjust_next = 0;
|
|
int remove_next = 0;
|
|
|
|
if (next && !insert) {
|
|
struct vm_area_struct *exporter = NULL, *importer = NULL;
|
|
|
|
if (end >= next->vm_end) {
|
|
/*
|
|
* vma expands, overlapping all the next, and
|
|
* perhaps the one after too (mprotect case 6).
|
|
* The only other cases that gets here are
|
|
* case 1, case 7 and case 8.
|
|
*/
|
|
if (next == expand) {
|
|
/*
|
|
* The only case where we don't expand "vma"
|
|
* and we expand "next" instead is case 8.
|
|
*/
|
|
VM_WARN_ON(end != next->vm_end);
|
|
/*
|
|
* remove_next == 3 means we're
|
|
* removing "vma" and that to do so we
|
|
* swapped "vma" and "next".
|
|
*/
|
|
remove_next = 3;
|
|
VM_WARN_ON(file != next->vm_file);
|
|
swap(vma, next);
|
|
} else {
|
|
VM_WARN_ON(expand != vma);
|
|
/*
|
|
* case 1, 6, 7, remove_next == 2 is case 6,
|
|
* remove_next == 1 is case 1 or 7.
|
|
*/
|
|
remove_next = 1 + (end > next->vm_end);
|
|
VM_WARN_ON(remove_next == 2 &&
|
|
end != next->vm_next->vm_end);
|
|
/* trim end to next, for case 6 first pass */
|
|
end = next->vm_end;
|
|
}
|
|
|
|
exporter = next;
|
|
importer = vma;
|
|
|
|
/*
|
|
* If next doesn't have anon_vma, import from vma after
|
|
* next, if the vma overlaps with it.
|
|
*/
|
|
if (remove_next == 2 && !next->anon_vma)
|
|
exporter = next->vm_next;
|
|
|
|
} else if (end > next->vm_start) {
|
|
/*
|
|
* vma expands, overlapping part of the next:
|
|
* mprotect case 5 shifting the boundary up.
|
|
*/
|
|
adjust_next = (end - next->vm_start);
|
|
exporter = next;
|
|
importer = vma;
|
|
VM_WARN_ON(expand != importer);
|
|
} else if (end < vma->vm_end) {
|
|
/*
|
|
* vma shrinks, and !insert tells it's not
|
|
* split_vma inserting another: so it must be
|
|
* mprotect case 4 shifting the boundary down.
|
|
*/
|
|
adjust_next = -(vma->vm_end - end);
|
|
exporter = vma;
|
|
importer = next;
|
|
VM_WARN_ON(expand != importer);
|
|
}
|
|
|
|
/*
|
|
* Easily overlooked: when mprotect shifts the boundary,
|
|
* make sure the expanding vma has anon_vma set if the
|
|
* shrinking vma had, to cover any anon pages imported.
|
|
*/
|
|
if (exporter && exporter->anon_vma && !importer->anon_vma) {
|
|
int error;
|
|
|
|
importer->anon_vma = exporter->anon_vma;
|
|
error = anon_vma_clone(importer, exporter);
|
|
if (error)
|
|
return error;
|
|
}
|
|
}
|
|
again:
|
|
vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
|
|
|
|
if (file) {
|
|
mapping = file->f_mapping;
|
|
root = &mapping->i_mmap;
|
|
uprobe_munmap(vma, vma->vm_start, vma->vm_end);
|
|
|
|
if (adjust_next)
|
|
uprobe_munmap(next, next->vm_start, next->vm_end);
|
|
|
|
i_mmap_lock_write(mapping);
|
|
if (insert) {
|
|
/*
|
|
* Put into interval tree now, so instantiated pages
|
|
* are visible to arm/parisc __flush_dcache_page
|
|
* throughout; but we cannot insert into address
|
|
* space until vma start or end is updated.
|
|
*/
|
|
__vma_link_file(insert);
|
|
}
|
|
}
|
|
|
|
anon_vma = vma->anon_vma;
|
|
if (!anon_vma && adjust_next)
|
|
anon_vma = next->anon_vma;
|
|
if (anon_vma) {
|
|
VM_WARN_ON(adjust_next && next->anon_vma &&
|
|
anon_vma != next->anon_vma);
|
|
anon_vma_lock_write(anon_vma);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
if (adjust_next)
|
|
anon_vma_interval_tree_pre_update_vma(next);
|
|
}
|
|
|
|
if (file) {
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_interval_tree_remove(vma, root);
|
|
if (adjust_next)
|
|
vma_interval_tree_remove(next, root);
|
|
}
|
|
|
|
if (start != vma->vm_start) {
|
|
vma->vm_start = start;
|
|
start_changed = true;
|
|
}
|
|
if (end != vma->vm_end) {
|
|
vma->vm_end = end;
|
|
end_changed = true;
|
|
}
|
|
vma->vm_pgoff = pgoff;
|
|
if (adjust_next) {
|
|
next->vm_start += adjust_next;
|
|
next->vm_pgoff += adjust_next >> PAGE_SHIFT;
|
|
}
|
|
|
|
if (file) {
|
|
if (adjust_next)
|
|
vma_interval_tree_insert(next, root);
|
|
vma_interval_tree_insert(vma, root);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
|
|
if (remove_next) {
|
|
/*
|
|
* vma_merge has merged next into vma, and needs
|
|
* us to remove next before dropping the locks.
|
|
*/
|
|
if (remove_next != 3)
|
|
__vma_unlink(mm, next, next);
|
|
else
|
|
/*
|
|
* vma is not before next if they've been
|
|
* swapped.
|
|
*
|
|
* pre-swap() next->vm_start was reduced so
|
|
* tell validate_mm_rb to ignore pre-swap()
|
|
* "next" (which is stored in post-swap()
|
|
* "vma").
|
|
*/
|
|
__vma_unlink(mm, next, vma);
|
|
if (file)
|
|
__remove_shared_vm_struct(next, file, mapping);
|
|
} else if (insert) {
|
|
/*
|
|
* split_vma has split insert from vma, and needs
|
|
* us to insert it before dropping the locks
|
|
* (it may either follow vma or precede it).
|
|
*/
|
|
__insert_vm_struct(mm, insert);
|
|
} else {
|
|
if (start_changed)
|
|
vma_gap_update(vma);
|
|
if (end_changed) {
|
|
if (!next)
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
else if (!adjust_next)
|
|
vma_gap_update(next);
|
|
}
|
|
}
|
|
|
|
if (anon_vma) {
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
if (adjust_next)
|
|
anon_vma_interval_tree_post_update_vma(next);
|
|
anon_vma_unlock_write(anon_vma);
|
|
}
|
|
|
|
if (file) {
|
|
i_mmap_unlock_write(mapping);
|
|
uprobe_mmap(vma);
|
|
|
|
if (adjust_next)
|
|
uprobe_mmap(next);
|
|
}
|
|
|
|
if (remove_next) {
|
|
if (file) {
|
|
uprobe_munmap(next, next->vm_start, next->vm_end);
|
|
fput(file);
|
|
}
|
|
if (next->anon_vma)
|
|
anon_vma_merge(vma, next);
|
|
mm->map_count--;
|
|
mpol_put(vma_policy(next));
|
|
vm_area_free(next);
|
|
/*
|
|
* In mprotect's case 6 (see comments on vma_merge),
|
|
* we must remove another next too. It would clutter
|
|
* up the code too much to do both in one go.
|
|
*/
|
|
if (remove_next != 3) {
|
|
/*
|
|
* If "next" was removed and vma->vm_end was
|
|
* expanded (up) over it, in turn
|
|
* "next->vm_prev->vm_end" changed and the
|
|
* "vma->vm_next" gap must be updated.
|
|
*/
|
|
next = vma->vm_next;
|
|
} else {
|
|
/*
|
|
* For the scope of the comment "next" and
|
|
* "vma" considered pre-swap(): if "vma" was
|
|
* removed, next->vm_start was expanded (down)
|
|
* over it and the "next" gap must be updated.
|
|
* Because of the swap() the post-swap() "vma"
|
|
* actually points to pre-swap() "next"
|
|
* (post-swap() "next" as opposed is now a
|
|
* dangling pointer).
|
|
*/
|
|
next = vma;
|
|
}
|
|
if (remove_next == 2) {
|
|
remove_next = 1;
|
|
end = next->vm_end;
|
|
goto again;
|
|
}
|
|
else if (next)
|
|
vma_gap_update(next);
|
|
else {
|
|
/*
|
|
* If remove_next == 2 we obviously can't
|
|
* reach this path.
|
|
*
|
|
* If remove_next == 3 we can't reach this
|
|
* path because pre-swap() next is always not
|
|
* NULL. pre-swap() "next" is not being
|
|
* removed and its next->vm_end is not altered
|
|
* (and furthermore "end" already matches
|
|
* next->vm_end in remove_next == 3).
|
|
*
|
|
* We reach this only in the remove_next == 1
|
|
* case if the "next" vma that was removed was
|
|
* the highest vma of the mm. However in such
|
|
* case next->vm_end == "end" and the extended
|
|
* "vma" has vma->vm_end == next->vm_end so
|
|
* mm->highest_vm_end doesn't need any update
|
|
* in remove_next == 1 case.
|
|
*/
|
|
VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
|
|
}
|
|
}
|
|
if (insert && file)
|
|
uprobe_mmap(insert);
|
|
|
|
validate_mm(mm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If the vma has a ->close operation then the driver probably needs to release
|
|
* per-vma resources, so we don't attempt to merge those.
|
|
*/
|
|
static inline int is_mergeable_vma(struct vm_area_struct *vma,
|
|
struct file *file, unsigned long vm_flags,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
const char *anon_name)
|
|
{
|
|
/*
|
|
* VM_SOFTDIRTY should not prevent from VMA merging, if we
|
|
* match the flags but dirty bit -- the caller should mark
|
|
* merged VMA as dirty. If dirty bit won't be excluded from
|
|
* comparison, we increase pressure on the memory system forcing
|
|
* the kernel to generate new VMAs when old one could be
|
|
* extended instead.
|
|
*/
|
|
if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
|
|
return 0;
|
|
if (vma->vm_file != file)
|
|
return 0;
|
|
if (vma->vm_ops && vma->vm_ops->close)
|
|
return 0;
|
|
if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
|
|
return 0;
|
|
if (!is_same_vma_anon_name(vma, anon_name))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
|
|
struct anon_vma *anon_vma2,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* The list_is_singular() test is to avoid merging VMA cloned from
|
|
* parents. This can improve scalability caused by anon_vma lock.
|
|
*/
|
|
if ((!anon_vma1 || !anon_vma2) && (!vma ||
|
|
list_is_singular(&vma->anon_vma_chain)))
|
|
return 1;
|
|
return anon_vma1 == anon_vma2;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* in front of (at a lower virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*
|
|
* We don't check here for the merged mmap wrapping around the end of pagecache
|
|
* indices (16TB on ia32) because do_mmap() does not permit mmap's which
|
|
* wrap, nor mmaps which cover the final page at index -1UL.
|
|
*/
|
|
static int
|
|
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
const char *anon_name)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
if (vma->vm_pgoff == vm_pgoff)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* beyond (at a higher virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*/
|
|
static int
|
|
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
const char *anon_name)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
pgoff_t vm_pglen;
|
|
vm_pglen = vma_pages(vma);
|
|
if (vma->vm_pgoff + vm_pglen == vm_pgoff)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
|
|
* figure out whether that can be merged with its predecessor or its
|
|
* successor. Or both (it neatly fills a hole).
|
|
*
|
|
* In most cases - when called for mmap, brk or mremap - [addr,end) is
|
|
* certain not to be mapped by the time vma_merge is called; but when
|
|
* called for mprotect, it is certain to be already mapped (either at
|
|
* an offset within prev, or at the start of next), and the flags of
|
|
* this area are about to be changed to vm_flags - and the no-change
|
|
* case has already been eliminated.
|
|
*
|
|
* The following mprotect cases have to be considered, where AAAA is
|
|
* the area passed down from mprotect_fixup, never extending beyond one
|
|
* vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
|
|
*
|
|
* AAAA AAAA AAAA
|
|
* PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN
|
|
* cannot merge might become might become
|
|
* PPNNNNNNNNNN PPPPPPPPPPNN
|
|
* mmap, brk or case 4 below case 5 below
|
|
* mremap move:
|
|
* AAAA AAAA
|
|
* PPPP NNNN PPPPNNNNXXXX
|
|
* might become might become
|
|
* PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
|
|
* PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or
|
|
* PPPPNNNNNNNN 3 PPPPXXXXXXXX 8
|
|
*
|
|
* It is important for case 8 that the vma NNNN overlapping the
|
|
* region AAAA is never going to extended over XXXX. Instead XXXX must
|
|
* be extended in region AAAA and NNNN must be removed. This way in
|
|
* all cases where vma_merge succeeds, the moment vma_adjust drops the
|
|
* rmap_locks, the properties of the merged vma will be already
|
|
* correct for the whole merged range. Some of those properties like
|
|
* vm_page_prot/vm_flags may be accessed by rmap_walks and they must
|
|
* be correct for the whole merged range immediately after the
|
|
* rmap_locks are released. Otherwise if XXXX would be removed and
|
|
* NNNN would be extended over the XXXX range, remove_migration_ptes
|
|
* or other rmap walkers (if working on addresses beyond the "end"
|
|
* parameter) may establish ptes with the wrong permissions of NNNN
|
|
* instead of the right permissions of XXXX.
|
|
*/
|
|
struct vm_area_struct *vma_merge(struct mm_struct *mm,
|
|
struct vm_area_struct *prev, unsigned long addr,
|
|
unsigned long end, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t pgoff, struct mempolicy *policy,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
|
|
const char *anon_name)
|
|
{
|
|
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
|
|
struct vm_area_struct *area, *next;
|
|
int err;
|
|
|
|
/*
|
|
* We later require that vma->vm_flags == vm_flags,
|
|
* so this tests vma->vm_flags & VM_SPECIAL, too.
|
|
*/
|
|
if (vm_flags & VM_SPECIAL)
|
|
return NULL;
|
|
|
|
next = vma_next(mm, prev);
|
|
area = next;
|
|
if (area && area->vm_end == end) /* cases 6, 7, 8 */
|
|
next = next->vm_next;
|
|
|
|
/* verify some invariant that must be enforced by the caller */
|
|
VM_WARN_ON(prev && addr <= prev->vm_start);
|
|
VM_WARN_ON(area && end > area->vm_end);
|
|
VM_WARN_ON(addr >= end);
|
|
|
|
/*
|
|
* Can it merge with the predecessor?
|
|
*/
|
|
if (prev && prev->vm_end == addr &&
|
|
mpol_equal(vma_policy(prev), policy) &&
|
|
can_vma_merge_after(prev, vm_flags,
|
|
anon_vma, file, pgoff,
|
|
vm_userfaultfd_ctx, anon_name)) {
|
|
/*
|
|
* OK, it can. Can we now merge in the successor as well?
|
|
*/
|
|
if (next && end == next->vm_start &&
|
|
mpol_equal(policy, vma_policy(next)) &&
|
|
can_vma_merge_before(next, vm_flags,
|
|
anon_vma, file,
|
|
pgoff+pglen,
|
|
vm_userfaultfd_ctx, anon_name) &&
|
|
is_mergeable_anon_vma(prev->anon_vma,
|
|
next->anon_vma, NULL)) {
|
|
/* cases 1, 6 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
next->vm_end, prev->vm_pgoff, NULL,
|
|
prev);
|
|
} else /* cases 2, 5, 7 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
end, prev->vm_pgoff, NULL, prev);
|
|
if (err)
|
|
return NULL;
|
|
khugepaged_enter_vma_merge(prev, vm_flags);
|
|
return prev;
|
|
}
|
|
|
|
/*
|
|
* Can this new request be merged in front of next?
|
|
*/
|
|
if (next && end == next->vm_start &&
|
|
mpol_equal(policy, vma_policy(next)) &&
|
|
can_vma_merge_before(next, vm_flags,
|
|
anon_vma, file, pgoff+pglen,
|
|
vm_userfaultfd_ctx, anon_name)) {
|
|
if (prev && addr < prev->vm_end) /* case 4 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
addr, prev->vm_pgoff, NULL, next);
|
|
else { /* cases 3, 8 */
|
|
err = __vma_adjust(area, addr, next->vm_end,
|
|
next->vm_pgoff - pglen, NULL, next);
|
|
/*
|
|
* In case 3 area is already equal to next and
|
|
* this is a noop, but in case 8 "area" has
|
|
* been removed and next was expanded over it.
|
|
*/
|
|
area = next;
|
|
}
|
|
if (err)
|
|
return NULL;
|
|
khugepaged_enter_vma_merge(area, vm_flags);
|
|
return area;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Rough compatibility check to quickly see if it's even worth looking
|
|
* at sharing an anon_vma.
|
|
*
|
|
* They need to have the same vm_file, and the flags can only differ
|
|
* in things that mprotect may change.
|
|
*
|
|
* NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
|
|
* we can merge the two vma's. For example, we refuse to merge a vma if
|
|
* there is a vm_ops->close() function, because that indicates that the
|
|
* driver is doing some kind of reference counting. But that doesn't
|
|
* really matter for the anon_vma sharing case.
|
|
*/
|
|
static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
return a->vm_end == b->vm_start &&
|
|
mpol_equal(vma_policy(a), vma_policy(b)) &&
|
|
a->vm_file == b->vm_file &&
|
|
!((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
|
|
b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
/*
|
|
* Do some basic sanity checking to see if we can re-use the anon_vma
|
|
* from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
|
|
* the same as 'old', the other will be the new one that is trying
|
|
* to share the anon_vma.
|
|
*
|
|
* NOTE! This runs with mm_sem held for reading, so it is possible that
|
|
* the anon_vma of 'old' is concurrently in the process of being set up
|
|
* by another page fault trying to merge _that_. But that's ok: if it
|
|
* is being set up, that automatically means that it will be a singleton
|
|
* acceptable for merging, so we can do all of this optimistically. But
|
|
* we do that READ_ONCE() to make sure that we never re-load the pointer.
|
|
*
|
|
* IOW: that the "list_is_singular()" test on the anon_vma_chain only
|
|
* matters for the 'stable anon_vma' case (ie the thing we want to avoid
|
|
* is to return an anon_vma that is "complex" due to having gone through
|
|
* a fork).
|
|
*
|
|
* We also make sure that the two vma's are compatible (adjacent,
|
|
* and with the same memory policies). That's all stable, even with just
|
|
* a read lock on the mm_sem.
|
|
*/
|
|
static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
if (anon_vma_compatible(a, b)) {
|
|
struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
|
|
|
|
if (anon_vma && list_is_singular(&old->anon_vma_chain))
|
|
return anon_vma;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_mergeable_anon_vma is used by anon_vma_prepare, to check
|
|
* neighbouring vmas for a suitable anon_vma, before it goes off
|
|
* to allocate a new anon_vma. It checks because a repetitive
|
|
* sequence of mprotects and faults may otherwise lead to distinct
|
|
* anon_vmas being allocated, preventing vma merge in subsequent
|
|
* mprotect.
|
|
*/
|
|
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma *anon_vma = NULL;
|
|
|
|
/* Try next first. */
|
|
if (vma->vm_next) {
|
|
anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
|
|
if (anon_vma)
|
|
return anon_vma;
|
|
}
|
|
|
|
/* Try prev next. */
|
|
if (vma->vm_prev)
|
|
anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
|
|
|
|
/*
|
|
* We might reach here with anon_vma == NULL if we can't find
|
|
* any reusable anon_vma.
|
|
* There's no absolute need to look only at touching neighbours:
|
|
* we could search further afield for "compatible" anon_vmas.
|
|
* But it would probably just be a waste of time searching,
|
|
* or lead to too many vmas hanging off the same anon_vma.
|
|
* We're trying to allow mprotect remerging later on,
|
|
* not trying to minimize memory used for anon_vmas.
|
|
*/
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* If a hint addr is less than mmap_min_addr change hint to be as
|
|
* low as possible but still greater than mmap_min_addr
|
|
*/
|
|
static inline unsigned long round_hint_to_min(unsigned long hint)
|
|
{
|
|
hint &= PAGE_MASK;
|
|
if (((void *)hint != NULL) &&
|
|
(hint < mmap_min_addr))
|
|
return PAGE_ALIGN(mmap_min_addr);
|
|
return hint;
|
|
}
|
|
|
|
int mlock_future_check(struct mm_struct *mm, unsigned long flags,
|
|
unsigned long len)
|
|
{
|
|
unsigned long locked, lock_limit;
|
|
|
|
/* mlock MCL_FUTURE? */
|
|
if (flags & VM_LOCKED) {
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += mm->locked_vm;
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
|
|
return -EAGAIN;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
|
|
{
|
|
if (S_ISREG(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
if (S_ISBLK(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
if (S_ISSOCK(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
/* Special "we do even unsigned file positions" case */
|
|
if (file->f_mode & FMODE_UNSIGNED_OFFSET)
|
|
return 0;
|
|
|
|
/* Yes, random drivers might want more. But I'm tired of buggy drivers */
|
|
return ULONG_MAX;
|
|
}
|
|
|
|
static inline bool file_mmap_ok(struct file *file, struct inode *inode,
|
|
unsigned long pgoff, unsigned long len)
|
|
{
|
|
u64 maxsize = file_mmap_size_max(file, inode);
|
|
|
|
if (maxsize && len > maxsize)
|
|
return false;
|
|
maxsize -= len;
|
|
if (pgoff > maxsize >> PAGE_SHIFT)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* The caller must write-lock current->mm->mmap_lock.
|
|
*/
|
|
unsigned long do_mmap(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flags, unsigned long pgoff,
|
|
unsigned long *populate, struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
vm_flags_t vm_flags;
|
|
int pkey = 0;
|
|
|
|
*populate = 0;
|
|
|
|
if (!len)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Does the application expect PROT_READ to imply PROT_EXEC?
|
|
*
|
|
* (the exception is when the underlying filesystem is noexec
|
|
* mounted, in which case we dont add PROT_EXEC.)
|
|
*/
|
|
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
|
|
if (!(file && path_noexec(&file->f_path)))
|
|
prot |= PROT_EXEC;
|
|
|
|
/* force arch specific MAP_FIXED handling in get_unmapped_area */
|
|
if (flags & MAP_FIXED_NOREPLACE)
|
|
flags |= MAP_FIXED;
|
|
|
|
if (!(flags & MAP_FIXED))
|
|
addr = round_hint_to_min(addr);
|
|
|
|
/* Careful about overflows.. */
|
|
len = PAGE_ALIGN(len);
|
|
if (!len)
|
|
return -ENOMEM;
|
|
|
|
/* offset overflow? */
|
|
if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
|
|
return -EOVERFLOW;
|
|
|
|
/* Too many mappings? */
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
/* Obtain the address to map to. we verify (or select) it and ensure
|
|
* that it represents a valid section of the address space.
|
|
*/
|
|
addr = get_unmapped_area(file, addr, len, pgoff, flags);
|
|
if (IS_ERR_VALUE(addr))
|
|
return addr;
|
|
|
|
if (flags & MAP_FIXED_NOREPLACE) {
|
|
if (find_vma_intersection(mm, addr, addr + len))
|
|
return -EEXIST;
|
|
}
|
|
|
|
if (prot == PROT_EXEC) {
|
|
pkey = execute_only_pkey(mm);
|
|
if (pkey < 0)
|
|
pkey = 0;
|
|
}
|
|
|
|
/* Do simple checking here so the lower-level routines won't have
|
|
* to. we assume access permissions have been handled by the open
|
|
* of the memory object, so we don't do any here.
|
|
*/
|
|
vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
|
|
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
|
|
|
|
if (flags & MAP_LOCKED)
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
if (mlock_future_check(mm, vm_flags, len))
|
|
return -EAGAIN;
|
|
|
|
if (file) {
|
|
struct inode *inode = file_inode(file);
|
|
unsigned long flags_mask;
|
|
|
|
if (!file_mmap_ok(file, inode, pgoff, len))
|
|
return -EOVERFLOW;
|
|
|
|
flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
|
|
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
/*
|
|
* Force use of MAP_SHARED_VALIDATE with non-legacy
|
|
* flags. E.g. MAP_SYNC is dangerous to use with
|
|
* MAP_SHARED as you don't know which consistency model
|
|
* you will get. We silently ignore unsupported flags
|
|
* with MAP_SHARED to preserve backward compatibility.
|
|
*/
|
|
flags &= LEGACY_MAP_MASK;
|
|
fallthrough;
|
|
case MAP_SHARED_VALIDATE:
|
|
if (flags & ~flags_mask)
|
|
return -EOPNOTSUPP;
|
|
if (prot & PROT_WRITE) {
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
if (IS_SWAPFILE(file->f_mapping->host))
|
|
return -ETXTBSY;
|
|
}
|
|
|
|
/*
|
|
* Make sure we don't allow writing to an append-only
|
|
* file..
|
|
*/
|
|
if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
|
|
fallthrough;
|
|
case MAP_PRIVATE:
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EACCES;
|
|
if (path_noexec(&file->f_path)) {
|
|
if (vm_flags & VM_EXEC)
|
|
return -EPERM;
|
|
vm_flags &= ~VM_MAYEXEC;
|
|
}
|
|
|
|
if (!file->f_op->mmap)
|
|
return -ENODEV;
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
break;
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
/*
|
|
* Ignore pgoff.
|
|
*/
|
|
pgoff = 0;
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
break;
|
|
case MAP_PRIVATE:
|
|
/*
|
|
* Set pgoff according to addr for anon_vma.
|
|
*/
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set 'VM_NORESERVE' if we should not account for the
|
|
* memory use of this mapping.
|
|
*/
|
|
if (flags & MAP_NORESERVE) {
|
|
/* We honor MAP_NORESERVE if allowed to overcommit */
|
|
if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
|
|
vm_flags |= VM_NORESERVE;
|
|
|
|
/* hugetlb applies strict overcommit unless MAP_NORESERVE */
|
|
if (file && is_file_hugepages(file))
|
|
vm_flags |= VM_NORESERVE;
|
|
}
|
|
|
|
addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
|
|
if (!IS_ERR_VALUE(addr) &&
|
|
((vm_flags & VM_LOCKED) ||
|
|
(flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
|
|
*populate = len;
|
|
return addr;
|
|
}
|
|
|
|
unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
|
|
unsigned long prot, unsigned long flags,
|
|
unsigned long fd, unsigned long pgoff)
|
|
{
|
|
struct file *file = NULL;
|
|
unsigned long retval;
|
|
|
|
if (!(flags & MAP_ANONYMOUS)) {
|
|
audit_mmap_fd(fd, flags);
|
|
file = fget(fd);
|
|
if (!file)
|
|
return -EBADF;
|
|
if (is_file_hugepages(file)) {
|
|
len = ALIGN(len, huge_page_size(hstate_file(file)));
|
|
} else if (unlikely(flags & MAP_HUGETLB)) {
|
|
retval = -EINVAL;
|
|
goto out_fput;
|
|
}
|
|
} else if (flags & MAP_HUGETLB) {
|
|
struct hstate *hs;
|
|
|
|
hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (!hs)
|
|
return -EINVAL;
|
|
|
|
len = ALIGN(len, huge_page_size(hs));
|
|
/*
|
|
* VM_NORESERVE is used because the reservations will be
|
|
* taken when vm_ops->mmap() is called
|
|
* A dummy user value is used because we are not locking
|
|
* memory so no accounting is necessary
|
|
*/
|
|
file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
|
|
VM_NORESERVE,
|
|
HUGETLB_ANONHUGE_INODE,
|
|
(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
}
|
|
|
|
retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
|
|
out_fput:
|
|
if (file)
|
|
fput(file);
|
|
return retval;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
|
|
unsigned long, prot, unsigned long, flags,
|
|
unsigned long, fd, unsigned long, pgoff)
|
|
{
|
|
return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_OLD_MMAP
|
|
struct mmap_arg_struct {
|
|
unsigned long addr;
|
|
unsigned long len;
|
|
unsigned long prot;
|
|
unsigned long flags;
|
|
unsigned long fd;
|
|
unsigned long offset;
|
|
};
|
|
|
|
SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
|
|
{
|
|
struct mmap_arg_struct a;
|
|
|
|
if (copy_from_user(&a, arg, sizeof(a)))
|
|
return -EFAULT;
|
|
if (offset_in_page(a.offset))
|
|
return -EINVAL;
|
|
|
|
return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
|
|
a.offset >> PAGE_SHIFT);
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_OLD_MMAP */
|
|
|
|
/*
|
|
* Some shared mappings will want the pages marked read-only
|
|
* to track write events. If so, we'll downgrade vm_page_prot
|
|
* to the private version (using protection_map[] without the
|
|
* VM_SHARED bit).
|
|
*/
|
|
int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
|
|
{
|
|
vm_flags_t vm_flags = vma->vm_flags;
|
|
const struct vm_operations_struct *vm_ops = vma->vm_ops;
|
|
|
|
/* If it was private or non-writable, the write bit is already clear */
|
|
if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
|
|
return 0;
|
|
|
|
/* The backer wishes to know when pages are first written to? */
|
|
if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
|
|
return 1;
|
|
|
|
/* The open routine did something to the protections that pgprot_modify
|
|
* won't preserve? */
|
|
if (pgprot_val(vm_page_prot) !=
|
|
pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
|
|
return 0;
|
|
|
|
/* Do we need to track softdirty? */
|
|
if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
|
|
return 1;
|
|
|
|
/* Specialty mapping? */
|
|
if (vm_flags & VM_PFNMAP)
|
|
return 0;
|
|
|
|
/* Can the mapping track the dirty pages? */
|
|
return vma->vm_file && vma->vm_file->f_mapping &&
|
|
mapping_can_writeback(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
/*
|
|
* We account for memory if it's a private writeable mapping,
|
|
* not hugepages and VM_NORESERVE wasn't set.
|
|
*/
|
|
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
|
|
{
|
|
/*
|
|
* hugetlb has its own accounting separate from the core VM
|
|
* VM_HUGETLB may not be set yet so we cannot check for that flag.
|
|
*/
|
|
if (file && is_file_hugepages(file))
|
|
return 0;
|
|
|
|
return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
|
|
}
|
|
|
|
unsigned long mmap_region(struct file *file, unsigned long addr,
|
|
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
|
|
struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev, *merge;
|
|
int error;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
unsigned long charged = 0;
|
|
|
|
/* Check against address space limit. */
|
|
if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
|
|
unsigned long nr_pages;
|
|
|
|
/*
|
|
* MAP_FIXED may remove pages of mappings that intersects with
|
|
* requested mapping. Account for the pages it would unmap.
|
|
*/
|
|
nr_pages = count_vma_pages_range(mm, addr, addr + len);
|
|
|
|
if (!may_expand_vm(mm, vm_flags,
|
|
(len >> PAGE_SHIFT) - nr_pages))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
|
|
if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
|
|
return -ENOMEM;
|
|
/*
|
|
* Private writable mapping: check memory availability
|
|
*/
|
|
if (accountable_mapping(file, vm_flags)) {
|
|
charged = len >> PAGE_SHIFT;
|
|
if (security_vm_enough_memory_mm(mm, charged))
|
|
return -ENOMEM;
|
|
vm_flags |= VM_ACCOUNT;
|
|
}
|
|
|
|
/*
|
|
* Can we just expand an old mapping?
|
|
*/
|
|
vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
|
|
NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
|
|
if (vma)
|
|
goto out;
|
|
|
|
/*
|
|
* Determine the object being mapped and call the appropriate
|
|
* specific mapper. the address has already been validated, but
|
|
* not unmapped, but the maps are removed from the list.
|
|
*/
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma) {
|
|
error = -ENOMEM;
|
|
goto unacct_error;
|
|
}
|
|
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
vma->vm_flags = vm_flags;
|
|
vma->vm_page_prot = vm_get_page_prot(vm_flags);
|
|
vma->vm_pgoff = pgoff;
|
|
|
|
if (file) {
|
|
if (vm_flags & VM_SHARED) {
|
|
error = mapping_map_writable(file->f_mapping);
|
|
if (error)
|
|
goto free_vma;
|
|
}
|
|
|
|
vma->vm_file = get_file(file);
|
|
error = call_mmap(file, vma);
|
|
if (error)
|
|
goto unmap_and_free_vma;
|
|
|
|
/* Can addr have changed??
|
|
*
|
|
* Answer: Yes, several device drivers can do it in their
|
|
* f_op->mmap method. -DaveM
|
|
* Bug: If addr is changed, prev, rb_link, rb_parent should
|
|
* be updated for vma_link()
|
|
*/
|
|
WARN_ON_ONCE(addr != vma->vm_start);
|
|
|
|
addr = vma->vm_start;
|
|
|
|
/* If vm_flags changed after call_mmap(), we should try merge vma again
|
|
* as we may succeed this time.
|
|
*/
|
|
if (unlikely(vm_flags != vma->vm_flags && prev)) {
|
|
merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
|
|
NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
|
|
if (merge) {
|
|
/* ->mmap() can change vma->vm_file and fput the original file. So
|
|
* fput the vma->vm_file here or we would add an extra fput for file
|
|
* and cause general protection fault ultimately.
|
|
*/
|
|
fput(vma->vm_file);
|
|
vm_area_free(vma);
|
|
vma = merge;
|
|
/* Update vm_flags to pick up the change. */
|
|
vm_flags = vma->vm_flags;
|
|
goto unmap_writable;
|
|
}
|
|
}
|
|
|
|
vm_flags = vma->vm_flags;
|
|
} else if (vm_flags & VM_SHARED) {
|
|
error = shmem_zero_setup(vma);
|
|
if (error)
|
|
goto free_vma;
|
|
} else {
|
|
vma_set_anonymous(vma);
|
|
}
|
|
|
|
/* Allow architectures to sanity-check the vm_flags */
|
|
if (!arch_validate_flags(vma->vm_flags)) {
|
|
error = -EINVAL;
|
|
if (file)
|
|
goto unmap_and_free_vma;
|
|
else
|
|
goto free_vma;
|
|
}
|
|
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
/* Once vma denies write, undo our temporary denial count */
|
|
unmap_writable:
|
|
if (file && vm_flags & VM_SHARED)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
file = vma->vm_file;
|
|
out:
|
|
perf_event_mmap(vma);
|
|
|
|
vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
|
|
if (vm_flags & VM_LOCKED) {
|
|
if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
|
|
is_vm_hugetlb_page(vma) ||
|
|
vma == get_gate_vma(current->mm))
|
|
vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
|
|
else
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
}
|
|
|
|
if (file)
|
|
uprobe_mmap(vma);
|
|
|
|
/*
|
|
* New (or expanded) vma always get soft dirty status.
|
|
* Otherwise user-space soft-dirty page tracker won't
|
|
* be able to distinguish situation when vma area unmapped,
|
|
* then new mapped in-place (which must be aimed as
|
|
* a completely new data area).
|
|
*/
|
|
vma->vm_flags |= VM_SOFTDIRTY;
|
|
|
|
vma_set_page_prot(vma);
|
|
|
|
return addr;
|
|
|
|
unmap_and_free_vma:
|
|
fput(vma->vm_file);
|
|
vma->vm_file = NULL;
|
|
|
|
/* Undo any partial mapping done by a device driver. */
|
|
unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
|
|
charged = 0;
|
|
if (vm_flags & VM_SHARED)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
free_vma:
|
|
vm_area_free(vma);
|
|
unacct_error:
|
|
if (charged)
|
|
vm_unacct_memory(charged);
|
|
return error;
|
|
}
|
|
|
|
static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
|
{
|
|
/*
|
|
* We implement the search by looking for an rbtree node that
|
|
* immediately follows a suitable gap. That is,
|
|
* - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
|
|
* - gap_end = vma->vm_start >= info->low_limit + length;
|
|
* - gap_end - gap_start >= length
|
|
*/
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long length, low_limit, high_limit, gap_start, gap_end;
|
|
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
/* Adjust search limits by the desired length */
|
|
if (info->high_limit < length)
|
|
return -ENOMEM;
|
|
high_limit = info->high_limit - length;
|
|
|
|
if (info->low_limit > high_limit)
|
|
return -ENOMEM;
|
|
low_limit = info->low_limit + length;
|
|
|
|
/* Check if rbtree root looks promising */
|
|
if (RB_EMPTY_ROOT(&mm->mm_rb))
|
|
goto check_highest;
|
|
vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
|
|
if (vma->rb_subtree_gap < length)
|
|
goto check_highest;
|
|
|
|
while (true) {
|
|
/* Visit left subtree if it looks promising */
|
|
gap_end = vm_start_gap(vma);
|
|
if (gap_end >= low_limit && vma->vm_rb.rb_left) {
|
|
struct vm_area_struct *left =
|
|
rb_entry(vma->vm_rb.rb_left,
|
|
struct vm_area_struct, vm_rb);
|
|
if (left->rb_subtree_gap >= length) {
|
|
vma = left;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
|
check_current:
|
|
/* Check if current node has a suitable gap */
|
|
if (gap_start > high_limit)
|
|
return -ENOMEM;
|
|
if (gap_end >= low_limit &&
|
|
gap_end > gap_start && gap_end - gap_start >= length)
|
|
goto found;
|
|
|
|
/* Visit right subtree if it looks promising */
|
|
if (vma->vm_rb.rb_right) {
|
|
struct vm_area_struct *right =
|
|
rb_entry(vma->vm_rb.rb_right,
|
|
struct vm_area_struct, vm_rb);
|
|
if (right->rb_subtree_gap >= length) {
|
|
vma = right;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Go back up the rbtree to find next candidate node */
|
|
while (true) {
|
|
struct rb_node *prev = &vma->vm_rb;
|
|
if (!rb_parent(prev))
|
|
goto check_highest;
|
|
vma = rb_entry(rb_parent(prev),
|
|
struct vm_area_struct, vm_rb);
|
|
if (prev == vma->vm_rb.rb_left) {
|
|
gap_start = vm_end_gap(vma->vm_prev);
|
|
gap_end = vm_start_gap(vma);
|
|
goto check_current;
|
|
}
|
|
}
|
|
}
|
|
|
|
check_highest:
|
|
/* Check highest gap, which does not precede any rbtree node */
|
|
gap_start = mm->highest_vm_end;
|
|
gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
|
|
if (gap_start > high_limit)
|
|
return -ENOMEM;
|
|
|
|
found:
|
|
/* We found a suitable gap. Clip it with the original low_limit. */
|
|
if (gap_start < info->low_limit)
|
|
gap_start = info->low_limit;
|
|
|
|
/* Adjust gap address to the desired alignment */
|
|
gap_start += (info->align_offset - gap_start) & info->align_mask;
|
|
|
|
VM_BUG_ON(gap_start + info->length > info->high_limit);
|
|
VM_BUG_ON(gap_start + info->length > gap_end);
|
|
return gap_start;
|
|
}
|
|
|
|
static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long length, low_limit, high_limit, gap_start, gap_end;
|
|
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Adjust search limits by the desired length.
|
|
* See implementation comment at top of unmapped_area().
|
|
*/
|
|
gap_end = info->high_limit;
|
|
if (gap_end < length)
|
|
return -ENOMEM;
|
|
high_limit = gap_end - length;
|
|
|
|
if (info->low_limit > high_limit)
|
|
return -ENOMEM;
|
|
low_limit = info->low_limit + length;
|
|
|
|
/* Check highest gap, which does not precede any rbtree node */
|
|
gap_start = mm->highest_vm_end;
|
|
if (gap_start <= high_limit)
|
|
goto found_highest;
|
|
|
|
/* Check if rbtree root looks promising */
|
|
if (RB_EMPTY_ROOT(&mm->mm_rb))
|
|
return -ENOMEM;
|
|
vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
|
|
if (vma->rb_subtree_gap < length)
|
|
return -ENOMEM;
|
|
|
|
while (true) {
|
|
/* Visit right subtree if it looks promising */
|
|
gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
|
if (gap_start <= high_limit && vma->vm_rb.rb_right) {
|
|
struct vm_area_struct *right =
|
|
rb_entry(vma->vm_rb.rb_right,
|
|
struct vm_area_struct, vm_rb);
|
|
if (right->rb_subtree_gap >= length) {
|
|
vma = right;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
check_current:
|
|
/* Check if current node has a suitable gap */
|
|
gap_end = vm_start_gap(vma);
|
|
if (gap_end < low_limit)
|
|
return -ENOMEM;
|
|
if (gap_start <= high_limit &&
|
|
gap_end > gap_start && gap_end - gap_start >= length)
|
|
goto found;
|
|
|
|
/* Visit left subtree if it looks promising */
|
|
if (vma->vm_rb.rb_left) {
|
|
struct vm_area_struct *left =
|
|
rb_entry(vma->vm_rb.rb_left,
|
|
struct vm_area_struct, vm_rb);
|
|
if (left->rb_subtree_gap >= length) {
|
|
vma = left;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Go back up the rbtree to find next candidate node */
|
|
while (true) {
|
|
struct rb_node *prev = &vma->vm_rb;
|
|
if (!rb_parent(prev))
|
|
return -ENOMEM;
|
|
vma = rb_entry(rb_parent(prev),
|
|
struct vm_area_struct, vm_rb);
|
|
if (prev == vma->vm_rb.rb_right) {
|
|
gap_start = vma->vm_prev ?
|
|
vm_end_gap(vma->vm_prev) : 0;
|
|
goto check_current;
|
|
}
|
|
}
|
|
}
|
|
|
|
found:
|
|
/* We found a suitable gap. Clip it with the original high_limit. */
|
|
if (gap_end > info->high_limit)
|
|
gap_end = info->high_limit;
|
|
|
|
found_highest:
|
|
/* Compute highest gap address at the desired alignment */
|
|
gap_end -= info->length;
|
|
gap_end -= (gap_end - info->align_offset) & info->align_mask;
|
|
|
|
VM_BUG_ON(gap_end < info->low_limit);
|
|
VM_BUG_ON(gap_end < gap_start);
|
|
return gap_end;
|
|
}
|
|
|
|
/*
|
|
* Search for an unmapped address range.
|
|
*
|
|
* We are looking for a range that:
|
|
* - does not intersect with any VMA;
|
|
* - is contained within the [low_limit, high_limit) interval;
|
|
* - is at least the desired size.
|
|
* - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
|
|
*/
|
|
unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
|
|
{
|
|
unsigned long addr;
|
|
|
|
if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
|
|
addr = unmapped_area_topdown(info);
|
|
else
|
|
addr = unmapped_area(info);
|
|
|
|
trace_vm_unmapped_area(addr, info);
|
|
return addr;
|
|
}
|
|
|
|
#ifndef arch_get_mmap_end
|
|
#define arch_get_mmap_end(addr) (TASK_SIZE)
|
|
#endif
|
|
|
|
#ifndef arch_get_mmap_base
|
|
#define arch_get_mmap_base(addr, base) (base)
|
|
#endif
|
|
|
|
/* Get an address range which is currently unmapped.
|
|
* For shmat() with addr=0.
|
|
*
|
|
* Ugly calling convention alert:
|
|
* Return value with the low bits set means error value,
|
|
* ie
|
|
* if (ret & ~PAGE_MASK)
|
|
* error = ret;
|
|
*
|
|
* This function "knows" that -ENOMEM has the bits set.
|
|
*/
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA
|
|
unsigned long
|
|
arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr);
|
|
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = 0;
|
|
info.length = len;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = mmap_end;
|
|
info.align_mask = 0;
|
|
info.align_offset = 0;
|
|
return vm_unmapped_area(&info);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* This mmap-allocator allocates new areas top-down from below the
|
|
* stack's low limit (the base):
|
|
*/
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
|
|
unsigned long
|
|
arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr);
|
|
|
|
/* requested length too big for entire address space */
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
/* requesting a specific address */
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
|
|
info.length = len;
|
|
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
|
|
info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
|
|
info.align_mask = 0;
|
|
info.align_offset = 0;
|
|
addr = vm_unmapped_area(&info);
|
|
|
|
/*
|
|
* A failed mmap() very likely causes application failure,
|
|
* so fall back to the bottom-up function here. This scenario
|
|
* can happen with large stack limits and large mmap()
|
|
* allocations.
|
|
*/
|
|
if (offset_in_page(addr)) {
|
|
VM_BUG_ON(addr != -ENOMEM);
|
|
info.flags = 0;
|
|
info.low_limit = TASK_UNMAPPED_BASE;
|
|
info.high_limit = mmap_end;
|
|
addr = vm_unmapped_area(&info);
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
#endif
|
|
|
|
unsigned long
|
|
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
|
|
unsigned long pgoff, unsigned long flags)
|
|
{
|
|
unsigned long (*get_area)(struct file *, unsigned long,
|
|
unsigned long, unsigned long, unsigned long);
|
|
|
|
unsigned long error = arch_mmap_check(addr, len, flags);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Careful about overflows.. */
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
get_area = current->mm->get_unmapped_area;
|
|
if (file) {
|
|
if (file->f_op->get_unmapped_area)
|
|
get_area = file->f_op->get_unmapped_area;
|
|
} else if (flags & MAP_SHARED) {
|
|
/*
|
|
* mmap_region() will call shmem_zero_setup() to create a file,
|
|
* so use shmem's get_unmapped_area in case it can be huge.
|
|
* do_mmap() will clear pgoff, so match alignment.
|
|
*/
|
|
pgoff = 0;
|
|
get_area = shmem_get_unmapped_area;
|
|
}
|
|
|
|
addr = get_area(file, addr, len, pgoff, flags);
|
|
if (IS_ERR_VALUE(addr))
|
|
return addr;
|
|
|
|
if (addr > TASK_SIZE - len)
|
|
return -ENOMEM;
|
|
if (offset_in_page(addr))
|
|
return -EINVAL;
|
|
|
|
error = security_mmap_addr(addr);
|
|
return error ? error : addr;
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_unmapped_area);
|
|
|
|
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
|
|
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct rb_node *rb_node;
|
|
struct vm_area_struct *vma;
|
|
|
|
mmap_assert_locked(mm);
|
|
/* Check the cache first. */
|
|
vma = vmacache_find(mm, addr);
|
|
if (likely(vma))
|
|
return vma;
|
|
|
|
rb_node = mm->mm_rb.rb_node;
|
|
|
|
while (rb_node) {
|
|
struct vm_area_struct *tmp;
|
|
|
|
tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
|
|
|
|
if (tmp->vm_end > addr) {
|
|
vma = tmp;
|
|
if (tmp->vm_start <= addr)
|
|
break;
|
|
rb_node = rb_node->rb_left;
|
|
} else
|
|
rb_node = rb_node->rb_right;
|
|
}
|
|
|
|
if (vma)
|
|
vmacache_update(addr, vma);
|
|
return vma;
|
|
}
|
|
|
|
EXPORT_SYMBOL(find_vma);
|
|
|
|
/*
|
|
* Same as find_vma, but also return a pointer to the previous VMA in *pprev.
|
|
*/
|
|
struct vm_area_struct *
|
|
find_vma_prev(struct mm_struct *mm, unsigned long addr,
|
|
struct vm_area_struct **pprev)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
|
|
vma = find_vma(mm, addr);
|
|
if (vma) {
|
|
*pprev = vma->vm_prev;
|
|
} else {
|
|
struct rb_node *rb_node = rb_last(&mm->mm_rb);
|
|
|
|
*pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
|
|
}
|
|
return vma;
|
|
}
|
|
|
|
/*
|
|
* Verify that the stack growth is acceptable and
|
|
* update accounting. This is shared with both the
|
|
* grow-up and grow-down cases.
|
|
*/
|
|
static int acct_stack_growth(struct vm_area_struct *vma,
|
|
unsigned long size, unsigned long grow)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long new_start;
|
|
|
|
/* address space limit tests */
|
|
if (!may_expand_vm(mm, vma->vm_flags, grow))
|
|
return -ENOMEM;
|
|
|
|
/* Stack limit test */
|
|
if (size > rlimit(RLIMIT_STACK))
|
|
return -ENOMEM;
|
|
|
|
/* mlock limit tests */
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
unsigned long locked;
|
|
unsigned long limit;
|
|
locked = mm->locked_vm + grow;
|
|
limit = rlimit(RLIMIT_MEMLOCK);
|
|
limit >>= PAGE_SHIFT;
|
|
if (locked > limit && !capable(CAP_IPC_LOCK))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Check to ensure the stack will not grow into a hugetlb-only region */
|
|
new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
|
|
vma->vm_end - size;
|
|
if (is_hugepage_only_range(vma->vm_mm, new_start, size))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* Overcommit.. This must be the final test, as it will
|
|
* update security statistics.
|
|
*/
|
|
if (security_vm_enough_memory_mm(mm, grow))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
|
|
/*
|
|
* PA-RISC uses this for its stack; IA64 for its Register Backing Store.
|
|
* vma is the last one with address > vma->vm_end. Have to extend vma.
|
|
*/
|
|
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next;
|
|
unsigned long gap_addr;
|
|
int error = 0;
|
|
|
|
if (!(vma->vm_flags & VM_GROWSUP))
|
|
return -EFAULT;
|
|
|
|
/* Guard against exceeding limits of the address space. */
|
|
address &= PAGE_MASK;
|
|
if (address >= (TASK_SIZE & PAGE_MASK))
|
|
return -ENOMEM;
|
|
address += PAGE_SIZE;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
gap_addr = address + stack_guard_gap;
|
|
|
|
/* Guard against overflow */
|
|
if (gap_addr < address || gap_addr > TASK_SIZE)
|
|
gap_addr = TASK_SIZE;
|
|
|
|
next = vma->vm_next;
|
|
if (next && next->vm_start < gap_addr && vma_is_accessible(next)) {
|
|
if (!(next->vm_flags & VM_GROWSUP))
|
|
return -ENOMEM;
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
}
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_lock in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address > vma->vm_end) {
|
|
unsigned long size, grow;
|
|
|
|
size = address - vma->vm_start;
|
|
grow = (address - vma->vm_end) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* vma_gap_update() doesn't support concurrent
|
|
* updates, but we only hold a shared mmap_lock
|
|
* lock here, so we need to protect against
|
|
* concurrent vma expansions.
|
|
* anon_vma_lock_write() doesn't help here, as
|
|
* we don't guarantee that all growable vmas
|
|
* in a mm share the same root anon vma.
|
|
* So, we reuse mm->page_table_lock to guard
|
|
* against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_end = address;
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
if (vma->vm_next)
|
|
vma_gap_update(vma->vm_next);
|
|
else
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
khugepaged_enter_vma_merge(vma, vma->vm_flags);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
|
|
|
|
/*
|
|
* vma is the first one with address < vma->vm_start. Have to extend vma.
|
|
*/
|
|
int expand_downwards(struct vm_area_struct *vma,
|
|
unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *prev;
|
|
int error = 0;
|
|
|
|
address &= PAGE_MASK;
|
|
if (address < mmap_min_addr)
|
|
return -EPERM;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
prev = vma->vm_prev;
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
|
|
vma_is_accessible(prev)) {
|
|
if (address - prev->vm_end < stack_guard_gap)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_lock in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address < vma->vm_start) {
|
|
unsigned long size, grow;
|
|
|
|
size = vma->vm_end - address;
|
|
grow = (vma->vm_start - address) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (grow <= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* vma_gap_update() doesn't support concurrent
|
|
* updates, but we only hold a shared mmap_lock
|
|
* lock here, so we need to protect against
|
|
* concurrent vma expansions.
|
|
* anon_vma_lock_write() doesn't help here, as
|
|
* we don't guarantee that all growable vmas
|
|
* in a mm share the same root anon vma.
|
|
* So, we reuse mm->page_table_lock to guard
|
|
* against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_start = address;
|
|
vma->vm_pgoff -= grow;
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
vma_gap_update(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
khugepaged_enter_vma_merge(vma, vma->vm_flags);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
|
|
/* enforced gap between the expanding stack and other mappings. */
|
|
unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
|
|
|
|
static int __init cmdline_parse_stack_guard_gap(char *p)
|
|
{
|
|
unsigned long val;
|
|
char *endptr;
|
|
|
|
val = simple_strtoul(p, &endptr, 10);
|
|
if (!*endptr)
|
|
stack_guard_gap = val << PAGE_SHIFT;
|
|
|
|
return 0;
|
|
}
|
|
__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
|
|
|
|
#ifdef CONFIG_STACK_GROWSUP
|
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_upwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *
|
|
find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (vma && (vma->vm_start <= addr))
|
|
return vma;
|
|
/* don't alter vm_end if the coredump is running */
|
|
if (!prev || expand_stack(prev, addr))
|
|
return NULL;
|
|
if (prev->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(prev, addr, prev->vm_end, NULL);
|
|
return prev;
|
|
}
|
|
#else
|
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_downwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *
|
|
find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long start;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma(mm, addr);
|
|
if (!vma)
|
|
return NULL;
|
|
if (vma->vm_start <= addr)
|
|
return vma;
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
return NULL;
|
|
start = vma->vm_start;
|
|
if (expand_stack(vma, addr))
|
|
return NULL;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(vma, addr, start, NULL);
|
|
return vma;
|
|
}
|
|
#endif
|
|
|
|
EXPORT_SYMBOL_GPL(find_extend_vma);
|
|
|
|
/*
|
|
* Ok - we have the memory areas we should free on the vma list,
|
|
* so release them, and do the vma updates.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long nr_accounted = 0;
|
|
|
|
/* Update high watermark before we lower total_vm */
|
|
update_hiwater_vm(mm);
|
|
do {
|
|
long nrpages = vma_pages(vma);
|
|
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += nrpages;
|
|
vm_stat_account(mm, vma->vm_flags, -nrpages);
|
|
vma = remove_vma(vma);
|
|
} while (vma);
|
|
vm_unacct_memory(nr_accounted);
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* Get rid of page table information in the indicated region.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static void unmap_region(struct mm_struct *mm,
|
|
struct vm_area_struct *vma, struct vm_area_struct *prev,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
struct vm_area_struct *next = vma_next(mm, prev);
|
|
struct mmu_gather tlb;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm);
|
|
update_hiwater_rss(mm);
|
|
unmap_vmas(&tlb, vma, start, end);
|
|
free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
|
|
next ? next->vm_start : USER_PGTABLES_CEILING);
|
|
tlb_finish_mmu(&tlb);
|
|
}
|
|
|
|
/*
|
|
* Create a list of vma's touched by the unmap, removing them from the mm's
|
|
* vma list as we go..
|
|
*/
|
|
static bool
|
|
detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, unsigned long end)
|
|
{
|
|
struct vm_area_struct **insertion_point;
|
|
struct vm_area_struct *tail_vma = NULL;
|
|
|
|
insertion_point = (prev ? &prev->vm_next : &mm->mmap);
|
|
vma->vm_prev = NULL;
|
|
do {
|
|
vma_rb_erase(vma, &mm->mm_rb);
|
|
mm->map_count--;
|
|
tail_vma = vma;
|
|
vma = vma->vm_next;
|
|
} while (vma && vma->vm_start < end);
|
|
*insertion_point = vma;
|
|
if (vma) {
|
|
vma->vm_prev = prev;
|
|
vma_gap_update(vma);
|
|
} else
|
|
mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
|
|
tail_vma->vm_next = NULL;
|
|
|
|
/* Kill the cache */
|
|
vmacache_invalidate(mm);
|
|
|
|
/*
|
|
* Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
|
|
* VM_GROWSUP VMA. Such VMAs can change their size under
|
|
* down_read(mmap_lock) and collide with the VMA we are about to unmap.
|
|
*/
|
|
if (vma && (vma->vm_flags & VM_GROWSDOWN))
|
|
return false;
|
|
if (prev && (prev->vm_flags & VM_GROWSUP))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* __split_vma() bypasses sysctl_max_map_count checking. We use this where it
|
|
* has already been checked or doesn't make sense to fail.
|
|
*/
|
|
int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
struct vm_area_struct *new;
|
|
int err;
|
|
|
|
if (vma->vm_ops && vma->vm_ops->may_split) {
|
|
err = vma->vm_ops->may_split(vma, addr);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
new = vm_area_dup(vma);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
if (new_below)
|
|
new->vm_end = addr;
|
|
else {
|
|
new->vm_start = addr;
|
|
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
err = vma_dup_policy(vma, new);
|
|
if (err)
|
|
goto out_free_vma;
|
|
|
|
err = anon_vma_clone(new, vma);
|
|
if (err)
|
|
goto out_free_mpol;
|
|
|
|
if (new->vm_file)
|
|
get_file(new->vm_file);
|
|
|
|
if (new->vm_ops && new->vm_ops->open)
|
|
new->vm_ops->open(new);
|
|
|
|
if (new_below)
|
|
err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
|
|
((addr - new->vm_start) >> PAGE_SHIFT), new);
|
|
else
|
|
err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
|
|
|
|
/* Success. */
|
|
if (!err)
|
|
return 0;
|
|
|
|
/* Clean everything up if vma_adjust failed. */
|
|
if (new->vm_ops && new->vm_ops->close)
|
|
new->vm_ops->close(new);
|
|
if (new->vm_file)
|
|
fput(new->vm_file);
|
|
unlink_anon_vmas(new);
|
|
out_free_mpol:
|
|
mpol_put(vma_policy(new));
|
|
out_free_vma:
|
|
vm_area_free(new);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Split a vma into two pieces at address 'addr', a new vma is allocated
|
|
* either for the first part or the tail.
|
|
*/
|
|
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
if (mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
return __split_vma(mm, vma, addr, new_below);
|
|
}
|
|
|
|
static inline void
|
|
unlock_range(struct vm_area_struct *start, unsigned long limit)
|
|
{
|
|
struct mm_struct *mm = start->vm_mm;
|
|
struct vm_area_struct *tmp = start;
|
|
|
|
while (tmp && tmp->vm_start < limit) {
|
|
if (tmp->vm_flags & VM_LOCKED) {
|
|
mm->locked_vm -= vma_pages(tmp);
|
|
munlock_vma_pages_all(tmp);
|
|
}
|
|
|
|
tmp = tmp->vm_next;
|
|
}
|
|
}
|
|
|
|
/* Munmap is split into 2 main parts -- this part which finds
|
|
* what needs doing, and the areas themselves, which do the
|
|
* work. This now handles partial unmappings.
|
|
* Jeremy Fitzhardinge <jeremy@goop.org>
|
|
*/
|
|
int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
|
|
struct list_head *uf, bool downgrade)
|
|
{
|
|
unsigned long end;
|
|
struct vm_area_struct *vma, *prev, *last;
|
|
|
|
if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
|
|
return -EINVAL;
|
|
|
|
len = PAGE_ALIGN(len);
|
|
end = start + len;
|
|
if (len == 0)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* arch_unmap() might do unmaps itself. It must be called
|
|
* and finish any rbtree manipulation before this code
|
|
* runs and also starts to manipulate the rbtree.
|
|
*/
|
|
arch_unmap(mm, start, end);
|
|
|
|
/* Find the first overlapping VMA where start < vma->vm_end */
|
|
vma = find_vma_intersection(mm, start, end);
|
|
if (!vma)
|
|
return 0;
|
|
prev = vma->vm_prev;
|
|
|
|
/*
|
|
* If we need to split any vma, do it now to save pain later.
|
|
*
|
|
* Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
|
|
* unmapped vm_area_struct will remain in use: so lower split_vma
|
|
* places tmp vma above, and higher split_vma places tmp vma below.
|
|
*/
|
|
if (start > vma->vm_start) {
|
|
int error;
|
|
|
|
/*
|
|
* Make sure that map_count on return from munmap() will
|
|
* not exceed its limit; but let map_count go just above
|
|
* its limit temporarily, to help free resources as expected.
|
|
*/
|
|
if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
error = __split_vma(mm, vma, start, 0);
|
|
if (error)
|
|
return error;
|
|
prev = vma;
|
|
}
|
|
|
|
/* Does it split the last one? */
|
|
last = find_vma(mm, end);
|
|
if (last && end > last->vm_start) {
|
|
int error = __split_vma(mm, last, end, 1);
|
|
if (error)
|
|
return error;
|
|
}
|
|
vma = vma_next(mm, prev);
|
|
|
|
if (unlikely(uf)) {
|
|
/*
|
|
* If userfaultfd_unmap_prep returns an error the vmas
|
|
* will remain split, but userland will get a
|
|
* highly unexpected error anyway. This is no
|
|
* different than the case where the first of the two
|
|
* __split_vma fails, but we don't undo the first
|
|
* split, despite we could. This is unlikely enough
|
|
* failure that it's not worth optimizing it for.
|
|
*/
|
|
int error = userfaultfd_unmap_prep(vma, start, end, uf);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* unlock any mlock()ed ranges before detaching vmas
|
|
*/
|
|
if (mm->locked_vm)
|
|
unlock_range(vma, end);
|
|
|
|
/* Detach vmas from rbtree */
|
|
if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
|
|
downgrade = false;
|
|
|
|
if (downgrade)
|
|
mmap_write_downgrade(mm);
|
|
|
|
unmap_region(mm, vma, prev, start, end);
|
|
|
|
/* Fix up all other VM information */
|
|
remove_vma_list(mm, vma);
|
|
|
|
return downgrade ? 1 : 0;
|
|
}
|
|
|
|
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
|
|
struct list_head *uf)
|
|
{
|
|
return __do_munmap(mm, start, len, uf, false);
|
|
}
|
|
|
|
static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
|
|
{
|
|
int ret;
|
|
struct mm_struct *mm = current->mm;
|
|
LIST_HEAD(uf);
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
ret = __do_munmap(mm, start, len, &uf, downgrade);
|
|
/*
|
|
* Returning 1 indicates mmap_lock is downgraded.
|
|
* But 1 is not legal return value of vm_munmap() and munmap(), reset
|
|
* it to 0 before return.
|
|
*/
|
|
if (ret == 1) {
|
|
mmap_read_unlock(mm);
|
|
ret = 0;
|
|
} else
|
|
mmap_write_unlock(mm);
|
|
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
return ret;
|
|
}
|
|
|
|
int vm_munmap(unsigned long start, size_t len)
|
|
{
|
|
return __vm_munmap(start, len, false);
|
|
}
|
|
EXPORT_SYMBOL(vm_munmap);
|
|
|
|
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
|
|
{
|
|
addr = untagged_addr(addr);
|
|
return __vm_munmap(addr, len, true);
|
|
}
|
|
|
|
|
|
/*
|
|
* Emulation of deprecated remap_file_pages() syscall.
|
|
*/
|
|
SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
|
|
unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
|
|
{
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long populate = 0;
|
|
unsigned long ret = -EINVAL;
|
|
struct file *file;
|
|
|
|
pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
|
|
current->comm, current->pid);
|
|
|
|
if (prot)
|
|
return ret;
|
|
start = start & PAGE_MASK;
|
|
size = size & PAGE_MASK;
|
|
|
|
if (start + size <= start)
|
|
return ret;
|
|
|
|
/* Does pgoff wrap? */
|
|
if (pgoff + (size >> PAGE_SHIFT) < pgoff)
|
|
return ret;
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
vma = vma_lookup(mm, start);
|
|
|
|
if (!vma || !(vma->vm_flags & VM_SHARED))
|
|
goto out;
|
|
|
|
if (start + size > vma->vm_end) {
|
|
struct vm_area_struct *next;
|
|
|
|
for (next = vma->vm_next; next; next = next->vm_next) {
|
|
/* hole between vmas ? */
|
|
if (next->vm_start != next->vm_prev->vm_end)
|
|
goto out;
|
|
|
|
if (next->vm_file != vma->vm_file)
|
|
goto out;
|
|
|
|
if (next->vm_flags != vma->vm_flags)
|
|
goto out;
|
|
|
|
if (start + size <= next->vm_end)
|
|
break;
|
|
}
|
|
|
|
if (!next)
|
|
goto out;
|
|
}
|
|
|
|
prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
|
|
prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
|
|
prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
|
|
|
|
flags &= MAP_NONBLOCK;
|
|
flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
flags |= MAP_LOCKED;
|
|
|
|
file = get_file(vma->vm_file);
|
|
ret = do_mmap(vma->vm_file, start, size,
|
|
prot, flags, pgoff, &populate, NULL);
|
|
fput(file);
|
|
out:
|
|
mmap_write_unlock(mm);
|
|
if (populate)
|
|
mm_populate(ret, populate);
|
|
if (!IS_ERR_VALUE(ret))
|
|
ret = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* this is really a simplified "do_mmap". it only handles
|
|
* anonymous maps. eventually we may be able to do some
|
|
* brk-specific accounting here.
|
|
*/
|
|
static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
pgoff_t pgoff = addr >> PAGE_SHIFT;
|
|
int error;
|
|
unsigned long mapped_addr;
|
|
|
|
/* Until we need other flags, refuse anything except VM_EXEC. */
|
|
if ((flags & (~VM_EXEC)) != 0)
|
|
return -EINVAL;
|
|
flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
|
|
|
|
mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
|
|
if (IS_ERR_VALUE(mapped_addr))
|
|
return mapped_addr;
|
|
|
|
error = mlock_future_check(mm, mm->def_flags, len);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
|
|
if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
|
|
return -ENOMEM;
|
|
|
|
/* Check against address space limits *after* clearing old maps... */
|
|
if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
/* Can we just expand an old private anonymous mapping? */
|
|
vma = vma_merge(mm, prev, addr, addr + len, flags,
|
|
NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
|
|
if (vma)
|
|
goto out;
|
|
|
|
/*
|
|
* create a vma struct for an anonymous mapping
|
|
*/
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma) {
|
|
vm_unacct_memory(len >> PAGE_SHIFT);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
vma_set_anonymous(vma);
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
vma->vm_pgoff = pgoff;
|
|
vma->vm_flags = flags;
|
|
vma->vm_page_prot = vm_get_page_prot(flags);
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
out:
|
|
perf_event_mmap(vma);
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
mm->data_vm += len >> PAGE_SHIFT;
|
|
if (flags & VM_LOCKED)
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
vma->vm_flags |= VM_SOFTDIRTY;
|
|
return 0;
|
|
}
|
|
|
|
int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long len;
|
|
int ret;
|
|
bool populate;
|
|
LIST_HEAD(uf);
|
|
|
|
len = PAGE_ALIGN(request);
|
|
if (len < request)
|
|
return -ENOMEM;
|
|
if (!len)
|
|
return 0;
|
|
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
|
|
ret = do_brk_flags(addr, len, flags, &uf);
|
|
populate = ((mm->def_flags & VM_LOCKED) != 0);
|
|
mmap_write_unlock(mm);
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
if (populate && !ret)
|
|
mm_populate(addr, len);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vm_brk_flags);
|
|
|
|
int vm_brk(unsigned long addr, unsigned long len)
|
|
{
|
|
return vm_brk_flags(addr, len, 0);
|
|
}
|
|
EXPORT_SYMBOL(vm_brk);
|
|
|
|
/* Release all mmaps. */
|
|
void exit_mmap(struct mm_struct *mm)
|
|
{
|
|
struct mmu_gather tlb;
|
|
struct vm_area_struct *vma;
|
|
unsigned long nr_accounted = 0;
|
|
|
|
/* mm's last user has gone, and its about to be pulled down */
|
|
mmu_notifier_release(mm);
|
|
|
|
if (unlikely(mm_is_oom_victim(mm))) {
|
|
/*
|
|
* Manually reap the mm to free as much memory as possible.
|
|
* Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
|
|
* this mm from further consideration. Taking mm->mmap_lock for
|
|
* write after setting MMF_OOM_SKIP will guarantee that the oom
|
|
* reaper will not run on this mm again after mmap_lock is
|
|
* dropped.
|
|
*
|
|
* Nothing can be holding mm->mmap_lock here and the above call
|
|
* to mmu_notifier_release(mm) ensures mmu notifier callbacks in
|
|
* __oom_reap_task_mm() will not block.
|
|
*
|
|
* This needs to be done before calling unlock_range(),
|
|
* which clears VM_LOCKED, otherwise the oom reaper cannot
|
|
* reliably test it.
|
|
*/
|
|
(void)__oom_reap_task_mm(mm);
|
|
|
|
set_bit(MMF_OOM_SKIP, &mm->flags);
|
|
}
|
|
|
|
mmap_write_lock(mm);
|
|
if (mm->locked_vm)
|
|
unlock_range(mm->mmap, ULONG_MAX);
|
|
|
|
arch_exit_mmap(mm);
|
|
|
|
vma = mm->mmap;
|
|
if (!vma) {
|
|
/* Can happen if dup_mmap() received an OOM */
|
|
mmap_write_unlock(mm);
|
|
return;
|
|
}
|
|
|
|
lru_add_drain();
|
|
flush_cache_mm(mm);
|
|
tlb_gather_mmu_fullmm(&tlb, mm);
|
|
/* update_hiwater_rss(mm) here? but nobody should be looking */
|
|
/* Use -1 here to ensure all VMAs in the mm are unmapped */
|
|
unmap_vmas(&tlb, vma, 0, -1);
|
|
free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
|
|
tlb_finish_mmu(&tlb);
|
|
|
|
/* Walk the list again, actually closing and freeing it. */
|
|
while (vma) {
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += vma_pages(vma);
|
|
vma = remove_vma(vma);
|
|
cond_resched();
|
|
}
|
|
mmap_write_unlock(mm);
|
|
vm_unacct_memory(nr_accounted);
|
|
}
|
|
|
|
/* Insert vm structure into process list sorted by address
|
|
* and into the inode's i_mmap tree. If vm_file is non-NULL
|
|
* then i_mmap_rwsem is taken here.
|
|
*/
|
|
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
|
|
if (find_vma_links(mm, vma->vm_start, vma->vm_end,
|
|
&prev, &rb_link, &rb_parent))
|
|
return -ENOMEM;
|
|
if ((vma->vm_flags & VM_ACCOUNT) &&
|
|
security_vm_enough_memory_mm(mm, vma_pages(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* The vm_pgoff of a purely anonymous vma should be irrelevant
|
|
* until its first write fault, when page's anon_vma and index
|
|
* are set. But now set the vm_pgoff it will almost certainly
|
|
* end up with (unless mremap moves it elsewhere before that
|
|
* first wfault), so /proc/pid/maps tells a consistent story.
|
|
*
|
|
* By setting it to reflect the virtual start address of the
|
|
* vma, merges and splits can happen in a seamless way, just
|
|
* using the existing file pgoff checks and manipulations.
|
|
* Similarly in do_mmap and in do_brk_flags.
|
|
*/
|
|
if (vma_is_anonymous(vma)) {
|
|
BUG_ON(vma->anon_vma);
|
|
vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
|
|
}
|
|
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Copy the vma structure to a new location in the same mm,
|
|
* prior to moving page table entries, to effect an mremap move.
|
|
*/
|
|
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
|
|
unsigned long addr, unsigned long len, pgoff_t pgoff,
|
|
bool *need_rmap_locks)
|
|
{
|
|
struct vm_area_struct *vma = *vmap;
|
|
unsigned long vma_start = vma->vm_start;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *new_vma, *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
bool faulted_in_anon_vma = true;
|
|
|
|
/*
|
|
* If anonymous vma has not yet been faulted, update new pgoff
|
|
* to match new location, to increase its chance of merging.
|
|
*/
|
|
if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
faulted_in_anon_vma = false;
|
|
}
|
|
|
|
if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
|
|
return NULL; /* should never get here */
|
|
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
|
|
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
|
|
vma->vm_userfaultfd_ctx, vma_anon_name(vma));
|
|
if (new_vma) {
|
|
/*
|
|
* Source vma may have been merged into new_vma
|
|
*/
|
|
if (unlikely(vma_start >= new_vma->vm_start &&
|
|
vma_start < new_vma->vm_end)) {
|
|
/*
|
|
* The only way we can get a vma_merge with
|
|
* self during an mremap is if the vma hasn't
|
|
* been faulted in yet and we were allowed to
|
|
* reset the dst vma->vm_pgoff to the
|
|
* destination address of the mremap to allow
|
|
* the merge to happen. mremap must change the
|
|
* vm_pgoff linearity between src and dst vmas
|
|
* (in turn preventing a vma_merge) to be
|
|
* safe. It is only safe to keep the vm_pgoff
|
|
* linear if there are no pages mapped yet.
|
|
*/
|
|
VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
|
|
*vmap = vma = new_vma;
|
|
}
|
|
*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
|
|
} else {
|
|
new_vma = vm_area_dup(vma);
|
|
if (!new_vma)
|
|
goto out;
|
|
new_vma->vm_start = addr;
|
|
new_vma->vm_end = addr + len;
|
|
new_vma->vm_pgoff = pgoff;
|
|
if (vma_dup_policy(vma, new_vma))
|
|
goto out_free_vma;
|
|
if (anon_vma_clone(new_vma, vma))
|
|
goto out_free_mempol;
|
|
if (new_vma->vm_file)
|
|
get_file(new_vma->vm_file);
|
|
if (new_vma->vm_ops && new_vma->vm_ops->open)
|
|
new_vma->vm_ops->open(new_vma);
|
|
vma_link(mm, new_vma, prev, rb_link, rb_parent);
|
|
*need_rmap_locks = false;
|
|
}
|
|
return new_vma;
|
|
|
|
out_free_mempol:
|
|
mpol_put(vma_policy(new_vma));
|
|
out_free_vma:
|
|
vm_area_free(new_vma);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Return true if the calling process may expand its vm space by the passed
|
|
* number of pages
|
|
*/
|
|
bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
|
|
{
|
|
if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
|
|
return false;
|
|
|
|
if (is_data_mapping(flags) &&
|
|
mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
|
|
/* Workaround for Valgrind */
|
|
if (rlimit(RLIMIT_DATA) == 0 &&
|
|
mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
|
|
return true;
|
|
|
|
pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
|
|
current->comm, current->pid,
|
|
(mm->data_vm + npages) << PAGE_SHIFT,
|
|
rlimit(RLIMIT_DATA),
|
|
ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
|
|
|
|
if (!ignore_rlimit_data)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
|
|
{
|
|
WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages);
|
|
|
|
if (is_exec_mapping(flags))
|
|
mm->exec_vm += npages;
|
|
else if (is_stack_mapping(flags))
|
|
mm->stack_vm += npages;
|
|
else if (is_data_mapping(flags))
|
|
mm->data_vm += npages;
|
|
}
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
|
|
|
|
/*
|
|
* Having a close hook prevents vma merging regardless of flags.
|
|
*/
|
|
static void special_mapping_close(struct vm_area_struct *vma)
|
|
{
|
|
}
|
|
|
|
static const char *special_mapping_name(struct vm_area_struct *vma)
|
|
{
|
|
return ((struct vm_special_mapping *)vma->vm_private_data)->name;
|
|
}
|
|
|
|
static int special_mapping_mremap(struct vm_area_struct *new_vma)
|
|
{
|
|
struct vm_special_mapping *sm = new_vma->vm_private_data;
|
|
|
|
if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
|
|
return -EFAULT;
|
|
|
|
if (sm->mremap)
|
|
return sm->mremap(sm, new_vma);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
|
|
{
|
|
/*
|
|
* Forbid splitting special mappings - kernel has expectations over
|
|
* the number of pages in mapping. Together with VM_DONTEXPAND
|
|
* the size of vma should stay the same over the special mapping's
|
|
* lifetime.
|
|
*/
|
|
return -EINVAL;
|
|
}
|
|
|
|
static const struct vm_operations_struct special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
.mremap = special_mapping_mremap,
|
|
.name = special_mapping_name,
|
|
/* vDSO code relies that VVAR can't be accessed remotely */
|
|
.access = NULL,
|
|
.may_split = special_mapping_split,
|
|
};
|
|
|
|
static const struct vm_operations_struct legacy_special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
};
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
pgoff_t pgoff;
|
|
struct page **pages;
|
|
|
|
if (vma->vm_ops == &legacy_special_mapping_vmops) {
|
|
pages = vma->vm_private_data;
|
|
} else {
|
|
struct vm_special_mapping *sm = vma->vm_private_data;
|
|
|
|
if (sm->fault)
|
|
return sm->fault(sm, vmf->vma, vmf);
|
|
|
|
pages = sm->pages;
|
|
}
|
|
|
|
for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
|
|
pgoff--;
|
|
|
|
if (*pages) {
|
|
struct page *page = *pages;
|
|
get_page(page);
|
|
vmf->page = page;
|
|
return 0;
|
|
}
|
|
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
static struct vm_area_struct *__install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, void *priv,
|
|
const struct vm_operations_struct *ops)
|
|
{
|
|
int ret;
|
|
struct vm_area_struct *vma;
|
|
|
|
vma = vm_area_alloc(mm);
|
|
if (unlikely(vma == NULL))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
|
|
vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
|
|
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
|
|
|
|
vma->vm_ops = ops;
|
|
vma->vm_private_data = priv;
|
|
|
|
ret = insert_vm_struct(mm, vma);
|
|
if (ret)
|
|
goto out;
|
|
|
|
vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
|
|
|
|
perf_event_mmap(vma);
|
|
|
|
return vma;
|
|
|
|
out:
|
|
vm_area_free(vma);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
bool vma_is_special_mapping(const struct vm_area_struct *vma,
|
|
const struct vm_special_mapping *sm)
|
|
{
|
|
return vma->vm_private_data == sm &&
|
|
(vma->vm_ops == &special_mapping_vmops ||
|
|
vma->vm_ops == &legacy_special_mapping_vmops);
|
|
}
|
|
|
|
/*
|
|
* Called with mm->mmap_lock held for writing.
|
|
* Insert a new vma covering the given region, with the given flags.
|
|
* Its pages are supplied by the given array of struct page *.
|
|
* The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
|
|
* The region past the last page supplied will always produce SIGBUS.
|
|
* The array pointer and the pages it points to are assumed to stay alive
|
|
* for as long as this mapping might exist.
|
|
*/
|
|
struct vm_area_struct *_install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, const struct vm_special_mapping *spec)
|
|
{
|
|
return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
|
|
&special_mapping_vmops);
|
|
}
|
|
|
|
int install_special_mapping(struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, struct page **pages)
|
|
{
|
|
struct vm_area_struct *vma = __install_special_mapping(
|
|
mm, addr, len, vm_flags, (void *)pages,
|
|
&legacy_special_mapping_vmops);
|
|
|
|
return PTR_ERR_OR_ZERO(vma);
|
|
}
|
|
|
|
static DEFINE_MUTEX(mm_all_locks_mutex);
|
|
|
|
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
|
|
{
|
|
if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
|
|
/*
|
|
* We can safely modify head.next after taking the
|
|
* anon_vma->root->rwsem. If some other vma in this mm shares
|
|
* the same anon_vma we won't take it again.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us thanks to the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (__test_and_set_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
|
|
{
|
|
if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change from under us because
|
|
* we hold the mm_all_locks_mutex.
|
|
*
|
|
* Operations on ->flags have to be atomic because
|
|
* even if AS_MM_ALL_LOCKS is stable thanks to the
|
|
* mm_all_locks_mutex, there may be other cpus
|
|
* changing other bitflags in parallel to us.
|
|
*/
|
|
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
|
|
BUG();
|
|
down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This operation locks against the VM for all pte/vma/mm related
|
|
* operations that could ever happen on a certain mm. This includes
|
|
* vmtruncate, try_to_unmap, and all page faults.
|
|
*
|
|
* The caller must take the mmap_lock in write mode before calling
|
|
* mm_take_all_locks(). The caller isn't allowed to release the
|
|
* mmap_lock until mm_drop_all_locks() returns.
|
|
*
|
|
* mmap_lock in write mode is required in order to block all operations
|
|
* that could modify pagetables and free pages without need of
|
|
* altering the vma layout. It's also needed in write mode to avoid new
|
|
* anon_vmas to be associated with existing vmas.
|
|
*
|
|
* A single task can't take more than one mm_take_all_locks() in a row
|
|
* or it would deadlock.
|
|
*
|
|
* The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
|
|
* mapping->flags avoid to take the same lock twice, if more than one
|
|
* vma in this mm is backed by the same anon_vma or address_space.
|
|
*
|
|
* We take locks in following order, accordingly to comment at beginning
|
|
* of mm/rmap.c:
|
|
* - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
|
|
* hugetlb mapping);
|
|
* - all i_mmap_rwsem locks;
|
|
* - all anon_vma->rwseml
|
|
*
|
|
* We can take all locks within these types randomly because the VM code
|
|
* doesn't nest them and we protected from parallel mm_take_all_locks() by
|
|
* mm_all_locks_mutex.
|
|
*
|
|
* mm_take_all_locks() and mm_drop_all_locks are expensive operations
|
|
* that may have to take thousand of locks.
|
|
*
|
|
* mm_take_all_locks() can fail if it's interrupted by signals.
|
|
*/
|
|
int mm_take_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
|
|
BUG_ON(mmap_read_trylock(mm));
|
|
|
|
mutex_lock(&mm_all_locks_mutex);
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
!is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_lock_anon_vma(mm, avc->anon_vma);
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_unlock:
|
|
mm_drop_all_locks(mm);
|
|
return -EINTR;
|
|
}
|
|
|
|
static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
|
|
{
|
|
if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change to 0 from under
|
|
* us because we hold the mm_all_locks_mutex.
|
|
*
|
|
* We must however clear the bitflag before unlocking
|
|
* the vma so the users using the anon_vma->rb_root will
|
|
* never see our bitflag.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us until we release the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (!__test_and_clear_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
anon_vma_unlock_write(anon_vma);
|
|
}
|
|
}
|
|
|
|
static void vm_unlock_mapping(struct address_space *mapping)
|
|
{
|
|
if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change to 0 from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
i_mmap_unlock_write(mapping);
|
|
if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
|
|
&mapping->flags))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The mmap_lock cannot be released by the caller until
|
|
* mm_drop_all_locks() returns.
|
|
*/
|
|
void mm_drop_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
|
|
BUG_ON(mmap_read_trylock(mm));
|
|
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_unlock_anon_vma(avc->anon_vma);
|
|
if (vma->vm_file && vma->vm_file->f_mapping)
|
|
vm_unlock_mapping(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
mutex_unlock(&mm_all_locks_mutex);
|
|
}
|
|
|
|
/*
|
|
* initialise the percpu counter for VM
|
|
*/
|
|
void __init mmap_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
|
|
VM_BUG_ON(ret);
|
|
}
|
|
|
|
/*
|
|
* Initialise sysctl_user_reserve_kbytes.
|
|
*
|
|
* This is intended to prevent a user from starting a single memory hogging
|
|
* process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
|
|
* mode.
|
|
*
|
|
* The default value is min(3% of free memory, 128MB)
|
|
* 128MB is enough to recover with sshd/login, bash, and top/kill.
|
|
*/
|
|
static int init_user_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_user_reserve);
|
|
|
|
/*
|
|
* Initialise sysctl_admin_reserve_kbytes.
|
|
*
|
|
* The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
|
|
* to log in and kill a memory hogging process.
|
|
*
|
|
* Systems with more than 256MB will reserve 8MB, enough to recover
|
|
* with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
|
|
* only reserve 3% of free pages by default.
|
|
*/
|
|
static int init_admin_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_admin_reserve);
|
|
|
|
/*
|
|
* Reinititalise user and admin reserves if memory is added or removed.
|
|
*
|
|
* The default user reserve max is 128MB, and the default max for the
|
|
* admin reserve is 8MB. These are usually, but not always, enough to
|
|
* enable recovery from a memory hogging process using login/sshd, a shell,
|
|
* and tools like top. It may make sense to increase or even disable the
|
|
* reserve depending on the existence of swap or variations in the recovery
|
|
* tools. So, the admin may have changed them.
|
|
*
|
|
* If memory is added and the reserves have been eliminated or increased above
|
|
* the default max, then we'll trust the admin.
|
|
*
|
|
* If memory is removed and there isn't enough free memory, then we
|
|
* need to reset the reserves.
|
|
*
|
|
* Otherwise keep the reserve set by the admin.
|
|
*/
|
|
static int reserve_mem_notifier(struct notifier_block *nb,
|
|
unsigned long action, void *data)
|
|
{
|
|
unsigned long tmp, free_kbytes;
|
|
|
|
switch (action) {
|
|
case MEM_ONLINE:
|
|
/* Default max is 128MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_user_reserve_kbytes;
|
|
if (0 < tmp && tmp < (1UL << 17))
|
|
init_user_reserve();
|
|
|
|
/* Default max is 8MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_admin_reserve_kbytes;
|
|
if (0 < tmp && tmp < (1UL << 13))
|
|
init_admin_reserve();
|
|
|
|
break;
|
|
case MEM_OFFLINE:
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
if (sysctl_user_reserve_kbytes > free_kbytes) {
|
|
init_user_reserve();
|
|
pr_info("vm.user_reserve_kbytes reset to %lu\n",
|
|
sysctl_user_reserve_kbytes);
|
|
}
|
|
|
|
if (sysctl_admin_reserve_kbytes > free_kbytes) {
|
|
init_admin_reserve();
|
|
pr_info("vm.admin_reserve_kbytes reset to %lu\n",
|
|
sysctl_admin_reserve_kbytes);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block reserve_mem_nb = {
|
|
.notifier_call = reserve_mem_notifier,
|
|
};
|
|
|
|
static int __meminit init_reserve_notifier(void)
|
|
{
|
|
if (register_hotmemory_notifier(&reserve_mem_nb))
|
|
pr_err("Failed registering memory add/remove notifier for admin reserve\n");
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_reserve_notifier);
|