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00a62ce91e
The Committed_AS field can underflow in certain situations: > # while true; do cat /proc/meminfo | grep _AS; sleep 1; done | uniq -c > 1 Committed_AS: 18446744073709323392 kB > 11 Committed_AS: 18446744073709455488 kB > 6 Committed_AS: 35136 kB > 5 Committed_AS: 18446744073709454400 kB > 7 Committed_AS: 35904 kB > 3 Committed_AS: 18446744073709453248 kB > 2 Committed_AS: 34752 kB > 9 Committed_AS: 18446744073709453248 kB > 8 Committed_AS: 34752 kB > 3 Committed_AS: 18446744073709320960 kB > 7 Committed_AS: 18446744073709454080 kB > 3 Committed_AS: 18446744073709320960 kB > 5 Committed_AS: 18446744073709454080 kB > 6 Committed_AS: 18446744073709320960 kB Because NR_CPUS can be greater than 1000 and meminfo_proc_show() does not check for underflow. But NR_CPUS proportional isn't good calculation. In general, possibility of lock contention is proportional to the number of online cpus, not theorical maximum cpus (NR_CPUS). The current kernel has generic percpu-counter stuff. using it is right way. it makes code simplify and percpu_counter_read_positive() don't make underflow issue. Reported-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Eric B Munson <ebmunson@us.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: <stable@kernel.org> [All kernel versions] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2485 lines
64 KiB
C
2485 lines
64 KiB
C
/*
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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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#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/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/ima.h>
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#include <linux/hugetlb.h>
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#include <linux/profile.h>
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#include <linux/module.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 <asm/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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#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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#ifndef arch_rebalance_pgtables
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#define arch_rebalance_pgtables(addr, len) (addr)
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#endif
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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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/*
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* WARNING: the debugging will use recursive algorithms so never enable this
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* unless you know what you are doing.
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*/
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#undef DEBUG_MM_RB
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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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*/
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pgprot_t protection_map[16] = {
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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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pgprot_t vm_get_page_prot(unsigned long vm_flags)
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{
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return __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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}
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EXPORT_SYMBOL(vm_get_page_prot);
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int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
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int sysctl_overcommit_ratio = 50; /* default is 50% */
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int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
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struct percpu_counter vm_committed_as;
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/*
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* Check that a process has enough memory to allocate a new virtual
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* mapping. 0 means there is enough memory for the allocation to
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* succeed and -ENOMEM implies there is not.
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*
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* We currently support three overcommit policies, which are set via the
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* vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
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*
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* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
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* Additional code 2002 Jul 20 by Robert Love.
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*
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* cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
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*
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* Note this is a helper function intended to be used by LSMs which
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* wish to use this logic.
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*/
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int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
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{
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unsigned long free, allowed;
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vm_acct_memory(pages);
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/*
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* Sometimes we want to use more memory than we have
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*/
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if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
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return 0;
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if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
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unsigned long n;
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free = global_page_state(NR_FILE_PAGES);
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free += nr_swap_pages;
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/*
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* Any slabs which are created with the
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* SLAB_RECLAIM_ACCOUNT flag claim to have contents
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* which are reclaimable, under pressure. The dentry
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* cache and most inode caches should fall into this
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*/
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free += global_page_state(NR_SLAB_RECLAIMABLE);
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/*
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* Leave the last 3% for root
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*/
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if (!cap_sys_admin)
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free -= free / 32;
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if (free > pages)
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return 0;
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/*
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* nr_free_pages() is very expensive on large systems,
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* only call if we're about to fail.
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*/
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n = nr_free_pages();
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/*
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* Leave reserved pages. The pages are not for anonymous pages.
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*/
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if (n <= totalreserve_pages)
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goto error;
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else
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n -= totalreserve_pages;
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/*
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* Leave the last 3% for root
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*/
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if (!cap_sys_admin)
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n -= n / 32;
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free += n;
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if (free > pages)
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return 0;
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goto error;
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}
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allowed = (totalram_pages - hugetlb_total_pages())
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* sysctl_overcommit_ratio / 100;
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/*
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* Leave the last 3% for root
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*/
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if (!cap_sys_admin)
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allowed -= allowed / 32;
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allowed += total_swap_pages;
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/* Don't let a single process grow too big:
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leave 3% of the size of this process for other processes */
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if (mm)
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allowed -= mm->total_vm / 32;
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if (percpu_counter_read_positive(&vm_committed_as) < allowed)
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return 0;
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error:
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vm_unacct_memory(pages);
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return -ENOMEM;
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}
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/*
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* Requires inode->i_mapping->i_mmap_lock
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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_DENYWRITE)
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atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
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if (vma->vm_flags & VM_SHARED)
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mapping->i_mmap_writable--;
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flush_dcache_mmap_lock(mapping);
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if (unlikely(vma->vm_flags & VM_NONLINEAR))
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list_del_init(&vma->shared.vm_set.list);
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else
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vma_prio_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 prio_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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spin_lock(&mapping->i_mmap_lock);
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__remove_shared_vm_struct(vma, file, mapping);
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spin_unlock(&mapping->i_mmap_lock);
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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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if (vma->vm_flags & VM_EXECUTABLE)
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removed_exe_file_vma(vma->vm_mm);
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}
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mpol_put(vma_policy(vma));
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kmem_cache_free(vm_area_cachep, vma);
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return next;
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}
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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
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unsigned long rlim, retval;
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unsigned long newbrk, oldbrk;
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struct mm_struct *mm = current->mm;
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unsigned long min_brk;
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down_write(&mm->mmap_sem);
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#ifdef CONFIG_COMPAT_BRK
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min_brk = mm->end_code;
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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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rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
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if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
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(mm->end_data - mm->start_data) > rlim)
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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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goto set_brk;
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/* Always allow shrinking brk. */
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if (brk <= mm->brk) {
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if (!do_munmap(mm, newbrk, oldbrk-newbrk))
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goto set_brk;
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goto out;
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}
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/* Check against existing mmap mappings. */
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if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
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goto out;
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/* Ok, looks good - let it rip. */
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if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
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goto out;
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set_brk:
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mm->brk = brk;
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out:
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retval = mm->brk;
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up_write(&mm->mmap_sem);
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return retval;
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}
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#ifdef DEBUG_MM_RB
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static int browse_rb(struct rb_root *root)
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{
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int i = 0, j;
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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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printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
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if (vma->vm_start < pend)
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printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
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if (vma->vm_start > vma->vm_end)
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printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
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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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}
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if (i != j)
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printk("backwards %d, forwards %d\n", j, i), i = 0;
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return i;
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}
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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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struct vm_area_struct *tmp = mm->mmap;
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while (tmp) {
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tmp = tmp->vm_next;
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i++;
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}
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if (i != mm->map_count)
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printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
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i = browse_rb(&mm->mm_rb);
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if (i != mm->map_count)
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printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
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BUG_ON(bug);
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}
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#else
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#define validate_mm(mm) do { } while (0)
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#endif
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static struct vm_area_struct *
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find_vma_prepare(struct mm_struct *mm, unsigned long addr,
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struct vm_area_struct **pprev, struct rb_node ***rb_link,
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struct rb_node ** rb_parent)
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{
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struct vm_area_struct * vma;
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struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
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__rb_link = &mm->mm_rb.rb_node;
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rb_prev = __rb_parent = NULL;
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vma = NULL;
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while (*__rb_link) {
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struct vm_area_struct *vma_tmp;
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__rb_parent = *__rb_link;
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vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
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if (vma_tmp->vm_end > addr) {
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vma = vma_tmp;
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if (vma_tmp->vm_start <= addr)
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break;
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__rb_link = &__rb_parent->rb_left;
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} else {
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rb_prev = __rb_parent;
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__rb_link = &__rb_parent->rb_right;
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}
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}
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*pprev = NULL;
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if (rb_prev)
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*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
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*rb_link = __rb_link;
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*rb_parent = __rb_parent;
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return vma;
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}
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static inline void
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__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev, struct rb_node *rb_parent)
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{
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if (prev) {
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vma->vm_next = prev->vm_next;
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prev->vm_next = vma;
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} else {
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mm->mmap = vma;
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if (rb_parent)
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vma->vm_next = rb_entry(rb_parent,
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struct vm_area_struct, vm_rb);
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else
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vma->vm_next = NULL;
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}
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}
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void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
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struct rb_node **rb_link, struct rb_node *rb_parent)
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{
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rb_link_node(&vma->vm_rb, rb_parent, rb_link);
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rb_insert_color(&vma->vm_rb, &mm->mm_rb);
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}
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static void __vma_link_file(struct vm_area_struct *vma)
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{
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struct file *file;
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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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if (vma->vm_flags & VM_DENYWRITE)
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atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
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if (vma->vm_flags & VM_SHARED)
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mapping->i_mmap_writable++;
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|
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flush_dcache_mmap_lock(mapping);
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if (unlikely(vma->vm_flags & VM_NONLINEAR))
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vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
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else
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vma_prio_tree_insert(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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|
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static void
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__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev, struct rb_node **rb_link,
|
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struct rb_node *rb_parent)
|
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{
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__vma_link_list(mm, vma, prev, rb_parent);
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__vma_link_rb(mm, vma, rb_link, rb_parent);
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__anon_vma_link(vma);
|
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}
|
|
|
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static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
|
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struct vm_area_struct *prev, struct rb_node **rb_link,
|
|
struct rb_node *rb_parent)
|
|
{
|
|
struct address_space *mapping = NULL;
|
|
|
|
if (vma->vm_file)
|
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mapping = vma->vm_file->f_mapping;
|
|
|
|
if (mapping) {
|
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spin_lock(&mapping->i_mmap_lock);
|
|
vma->vm_truncate_count = mapping->truncate_count;
|
|
}
|
|
anon_vma_lock(vma);
|
|
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
__vma_link_file(vma);
|
|
|
|
anon_vma_unlock(vma);
|
|
if (mapping)
|
|
spin_unlock(&mapping->i_mmap_lock);
|
|
|
|
mm->map_count++;
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* Helper for vma_adjust in the split_vma insert case:
|
|
* insert vm structure into list and rbtree and anon_vma,
|
|
* but it has already been inserted into prio_tree earlier.
|
|
*/
|
|
static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *__vma, *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
|
|
__vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
|
|
BUG_ON(__vma && __vma->vm_start < vma->vm_end);
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
mm->map_count++;
|
|
}
|
|
|
|
static inline void
|
|
__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev)
|
|
{
|
|
prev->vm_next = vma->vm_next;
|
|
rb_erase(&vma->vm_rb, &mm->mm_rb);
|
|
if (mm->mmap_cache == vma)
|
|
mm->mmap_cache = prev;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
void vma_adjust(struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next = vma->vm_next;
|
|
struct vm_area_struct *importer = NULL;
|
|
struct address_space *mapping = NULL;
|
|
struct prio_tree_root *root = NULL;
|
|
struct file *file = vma->vm_file;
|
|
struct anon_vma *anon_vma = NULL;
|
|
long adjust_next = 0;
|
|
int remove_next = 0;
|
|
|
|
if (next && !insert) {
|
|
if (end >= next->vm_end) {
|
|
/*
|
|
* vma expands, overlapping all the next, and
|
|
* perhaps the one after too (mprotect case 6).
|
|
*/
|
|
again: remove_next = 1 + (end > next->vm_end);
|
|
end = next->vm_end;
|
|
anon_vma = next->anon_vma;
|
|
importer = vma;
|
|
} 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) >> PAGE_SHIFT;
|
|
anon_vma = next->anon_vma;
|
|
importer = vma;
|
|
} 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) >> PAGE_SHIFT);
|
|
anon_vma = next->anon_vma;
|
|
importer = next;
|
|
}
|
|
}
|
|
|
|
if (file) {
|
|
mapping = file->f_mapping;
|
|
if (!(vma->vm_flags & VM_NONLINEAR))
|
|
root = &mapping->i_mmap;
|
|
spin_lock(&mapping->i_mmap_lock);
|
|
if (importer &&
|
|
vma->vm_truncate_count != next->vm_truncate_count) {
|
|
/*
|
|
* unmap_mapping_range might be in progress:
|
|
* ensure that the expanding vma is rescanned.
|
|
*/
|
|
importer->vm_truncate_count = 0;
|
|
}
|
|
if (insert) {
|
|
insert->vm_truncate_count = vma->vm_truncate_count;
|
|
/*
|
|
* Put into prio_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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* When changing only vma->vm_end, we don't really need
|
|
* anon_vma lock: but is that case worth optimizing out?
|
|
*/
|
|
if (vma->anon_vma)
|
|
anon_vma = vma->anon_vma;
|
|
if (anon_vma) {
|
|
spin_lock(&anon_vma->lock);
|
|
/*
|
|
* 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 (importer && !importer->anon_vma) {
|
|
importer->anon_vma = anon_vma;
|
|
__anon_vma_link(importer);
|
|
}
|
|
}
|
|
|
|
if (root) {
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_prio_tree_remove(vma, root);
|
|
if (adjust_next)
|
|
vma_prio_tree_remove(next, root);
|
|
}
|
|
|
|
vma->vm_start = start;
|
|
vma->vm_end = end;
|
|
vma->vm_pgoff = pgoff;
|
|
if (adjust_next) {
|
|
next->vm_start += adjust_next << PAGE_SHIFT;
|
|
next->vm_pgoff += adjust_next;
|
|
}
|
|
|
|
if (root) {
|
|
if (adjust_next)
|
|
vma_prio_tree_insert(next, root);
|
|
vma_prio_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.
|
|
*/
|
|
__vma_unlink(mm, next, vma);
|
|
if (file)
|
|
__remove_shared_vm_struct(next, file, mapping);
|
|
if (next->anon_vma)
|
|
__anon_vma_merge(vma, next);
|
|
} 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);
|
|
}
|
|
|
|
if (anon_vma)
|
|
spin_unlock(&anon_vma->lock);
|
|
if (mapping)
|
|
spin_unlock(&mapping->i_mmap_lock);
|
|
|
|
if (remove_next) {
|
|
if (file) {
|
|
fput(file);
|
|
if (next->vm_flags & VM_EXECUTABLE)
|
|
removed_exe_file_vma(mm);
|
|
}
|
|
mm->map_count--;
|
|
mpol_put(vma_policy(next));
|
|
kmem_cache_free(vm_area_cachep, 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 == 2) {
|
|
next = vma->vm_next;
|
|
goto again;
|
|
}
|
|
}
|
|
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/* Flags that can be inherited from an existing mapping when merging */
|
|
#define VM_MERGEABLE_FLAGS (VM_CAN_NONLINEAR)
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
if ((vma->vm_flags ^ vm_flags) & ~VM_MERGEABLE_FLAGS)
|
|
return 0;
|
|
if (vma->vm_file != file)
|
|
return 0;
|
|
if (vma->vm_ops && vma->vm_ops->close)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
|
|
struct anon_vma *anon_vma2)
|
|
{
|
|
return !anon_vma1 || !anon_vma2 || (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_pgoff() 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)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_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)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
|
|
pgoff_t vm_pglen;
|
|
vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
|
|
if (vma->vm_pgoff + vm_pglen == vm_pgoff)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Given a mapping request (addr,end,vm_flags,file,pgoff), 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 AAAA
|
|
* PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
|
|
* cannot merge might become might become might become
|
|
* PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
|
|
* mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
|
|
* mremap move: PPPPNNNNNNNN 8
|
|
* AAAA
|
|
* PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
|
|
* might become case 1 below case 2 below case 3 below
|
|
*
|
|
* Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
|
|
* mprotect_fixup updates vm_flags & vm_page_prot on successful return.
|
|
*/
|
|
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)
|
|
{
|
|
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
|
|
struct vm_area_struct *area, *next;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
if (prev)
|
|
next = prev->vm_next;
|
|
else
|
|
next = mm->mmap;
|
|
area = next;
|
|
if (next && next->vm_end == end) /* cases 6, 7, 8 */
|
|
next = next->vm_next;
|
|
|
|
/*
|
|
* 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)) {
|
|
/*
|
|
* 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) &&
|
|
is_mergeable_anon_vma(prev->anon_vma,
|
|
next->anon_vma)) {
|
|
/* cases 1, 6 */
|
|
vma_adjust(prev, prev->vm_start,
|
|
next->vm_end, prev->vm_pgoff, NULL);
|
|
} else /* cases 2, 5, 7 */
|
|
vma_adjust(prev, prev->vm_start,
|
|
end, prev->vm_pgoff, NULL);
|
|
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)) {
|
|
if (prev && addr < prev->vm_end) /* case 4 */
|
|
vma_adjust(prev, prev->vm_start,
|
|
addr, prev->vm_pgoff, NULL);
|
|
else /* cases 3, 8 */
|
|
vma_adjust(area, addr, next->vm_end,
|
|
next->vm_pgoff - pglen, NULL);
|
|
return area;
|
|
}
|
|
|
|
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 vm_area_struct *near;
|
|
unsigned long vm_flags;
|
|
|
|
near = vma->vm_next;
|
|
if (!near)
|
|
goto try_prev;
|
|
|
|
/*
|
|
* Since only mprotect tries to remerge vmas, match flags
|
|
* which might be mprotected into each other later on.
|
|
* Neither mlock nor madvise tries to remerge at present,
|
|
* so leave their flags as obstructing a merge.
|
|
*/
|
|
vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
|
|
vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
|
|
|
|
if (near->anon_vma && vma->vm_end == near->vm_start &&
|
|
mpol_equal(vma_policy(vma), vma_policy(near)) &&
|
|
can_vma_merge_before(near, vm_flags,
|
|
NULL, vma->vm_file, vma->vm_pgoff +
|
|
((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
|
|
return near->anon_vma;
|
|
try_prev:
|
|
/*
|
|
* It is potentially slow to have to call find_vma_prev here.
|
|
* But it's only on the first write fault on the vma, not
|
|
* every time, and we could devise a way to avoid it later
|
|
* (e.g. stash info in next's anon_vma_node when assigning
|
|
* an anon_vma, or when trying vma_merge). Another time.
|
|
*/
|
|
BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
|
|
if (!near)
|
|
goto none;
|
|
|
|
vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
|
|
vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
|
|
|
|
if (near->anon_vma && near->vm_end == vma->vm_start &&
|
|
mpol_equal(vma_policy(near), vma_policy(vma)) &&
|
|
can_vma_merge_after(near, vm_flags,
|
|
NULL, vma->vm_file, vma->vm_pgoff))
|
|
return near->anon_vma;
|
|
none:
|
|
/*
|
|
* 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 NULL;
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
|
|
struct file *file, long pages)
|
|
{
|
|
const unsigned long stack_flags
|
|
= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
|
|
|
|
if (file) {
|
|
mm->shared_vm += pages;
|
|
if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
|
|
mm->exec_vm += pages;
|
|
} else if (flags & stack_flags)
|
|
mm->stack_vm += pages;
|
|
if (flags & (VM_RESERVED|VM_IO))
|
|
mm->reserved_vm += pages;
|
|
}
|
|
#endif /* CONFIG_PROC_FS */
|
|
|
|
/*
|
|
* The caller must hold down_write(current->mm->mmap_sem).
|
|
*/
|
|
|
|
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flags, unsigned long pgoff)
|
|
{
|
|
struct mm_struct * mm = current->mm;
|
|
struct inode *inode;
|
|
unsigned int vm_flags;
|
|
int error;
|
|
unsigned long reqprot = prot;
|
|
|
|
/*
|
|
* 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 && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
|
|
prot |= PROT_EXEC;
|
|
|
|
if (!len)
|
|
return -EINVAL;
|
|
|
|
if (!(flags & MAP_FIXED))
|
|
addr = round_hint_to_min(addr);
|
|
|
|
error = arch_mmap_check(addr, len, flags);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Careful about overflows.. */
|
|
len = PAGE_ALIGN(len);
|
|
if (!len || len > TASK_SIZE)
|
|
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 (addr & ~PAGE_MASK)
|
|
return addr;
|
|
|
|
/* 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) | calc_vm_flag_bits(flags) |
|
|
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
|
|
|
|
if (flags & MAP_LOCKED) {
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
vm_flags |= VM_LOCKED;
|
|
}
|
|
|
|
/* mlock MCL_FUTURE? */
|
|
if (vm_flags & VM_LOCKED) {
|
|
unsigned long locked, lock_limit;
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += mm->locked_vm;
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
|
|
return -EAGAIN;
|
|
}
|
|
|
|
inode = file ? file->f_path.dentry->d_inode : NULL;
|
|
|
|
if (file) {
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
/*
|
|
* Make sure we don't allow writing to an append-only
|
|
* file..
|
|
*/
|
|
if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
/*
|
|
* Make sure there are no mandatory locks on the file.
|
|
*/
|
|
if (locks_verify_locked(inode))
|
|
return -EAGAIN;
|
|
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
|
|
|
|
/* fall through */
|
|
case MAP_PRIVATE:
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EACCES;
|
|
if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
|
|
if (vm_flags & VM_EXEC)
|
|
return -EPERM;
|
|
vm_flags &= ~VM_MAYEXEC;
|
|
}
|
|
|
|
if (!file->f_op || !file->f_op->mmap)
|
|
return -ENODEV;
|
|
break;
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
|
|
error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
|
|
if (error)
|
|
return error;
|
|
error = ima_file_mmap(file, prot);
|
|
if (error)
|
|
return error;
|
|
|
|
return mmap_region(file, addr, len, flags, vm_flags, pgoff);
|
|
}
|
|
EXPORT_SYMBOL(do_mmap_pgoff);
|
|
|
|
/*
|
|
* Some shared mappigns 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)
|
|
{
|
|
unsigned int vm_flags = vma->vm_flags;
|
|
|
|
/* 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 (vma->vm_ops && vma->vm_ops->page_mkwrite)
|
|
return 1;
|
|
|
|
/* The open routine did something to the protections already? */
|
|
if (pgprot_val(vma->vm_page_prot) !=
|
|
pgprot_val(vm_get_page_prot(vm_flags)))
|
|
return 0;
|
|
|
|
/* Specialty mapping? */
|
|
if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
|
|
return 0;
|
|
|
|
/* Can the mapping track the dirty pages? */
|
|
return vma->vm_file && vma->vm_file->f_mapping &&
|
|
mapping_cap_account_dirty(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, unsigned int 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, unsigned long flags,
|
|
unsigned int vm_flags, unsigned long pgoff)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
int correct_wcount = 0;
|
|
int error;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
unsigned long charged = 0;
|
|
struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
|
|
|
|
/* Clear old maps */
|
|
error = -ENOMEM;
|
|
munmap_back:
|
|
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
|
|
if (vma && vma->vm_start < addr + len) {
|
|
if (do_munmap(mm, addr, len))
|
|
return -ENOMEM;
|
|
goto munmap_back;
|
|
}
|
|
|
|
/* Check against address space limit. */
|
|
if (!may_expand_vm(mm, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/*
|
|
* Private writable mapping: check memory availability
|
|
*/
|
|
if (accountable_mapping(file, vm_flags)) {
|
|
charged = len >> PAGE_SHIFT;
|
|
if (security_vm_enough_memory(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);
|
|
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 = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
|
|
if (!vma) {
|
|
error = -ENOMEM;
|
|
goto unacct_error;
|
|
}
|
|
|
|
vma->vm_mm = mm;
|
|
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) {
|
|
error = -EINVAL;
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
goto free_vma;
|
|
if (vm_flags & VM_DENYWRITE) {
|
|
error = deny_write_access(file);
|
|
if (error)
|
|
goto free_vma;
|
|
correct_wcount = 1;
|
|
}
|
|
vma->vm_file = file;
|
|
get_file(file);
|
|
error = file->f_op->mmap(file, vma);
|
|
if (error)
|
|
goto unmap_and_free_vma;
|
|
if (vm_flags & VM_EXECUTABLE)
|
|
added_exe_file_vma(mm);
|
|
} else if (vm_flags & VM_SHARED) {
|
|
error = shmem_zero_setup(vma);
|
|
if (error)
|
|
goto free_vma;
|
|
}
|
|
|
|
/* Can addr have changed??
|
|
*
|
|
* Answer: Yes, several device drivers can do it in their
|
|
* f_op->mmap method. -DaveM
|
|
*/
|
|
addr = vma->vm_start;
|
|
pgoff = vma->vm_pgoff;
|
|
vm_flags = vma->vm_flags;
|
|
|
|
if (vma_wants_writenotify(vma))
|
|
vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
|
|
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
file = vma->vm_file;
|
|
|
|
/* Once vma denies write, undo our temporary denial count */
|
|
if (correct_wcount)
|
|
atomic_inc(&inode->i_writecount);
|
|
out:
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
|
|
if (vm_flags & VM_LOCKED) {
|
|
/*
|
|
* makes pages present; downgrades, drops, reacquires mmap_sem
|
|
*/
|
|
long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
|
|
if (nr_pages < 0)
|
|
return nr_pages; /* vma gone! */
|
|
mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
|
|
} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
|
|
make_pages_present(addr, addr + len);
|
|
return addr;
|
|
|
|
unmap_and_free_vma:
|
|
if (correct_wcount)
|
|
atomic_inc(&inode->i_writecount);
|
|
vma->vm_file = NULL;
|
|
fput(file);
|
|
|
|
/* Undo any partial mapping done by a device driver. */
|
|
unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
|
|
charged = 0;
|
|
free_vma:
|
|
kmem_cache_free(vm_area_cachep, vma);
|
|
unacct_error:
|
|
if (charged)
|
|
vm_unacct_memory(charged);
|
|
return error;
|
|
}
|
|
|
|
/* 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;
|
|
unsigned long start_addr;
|
|
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma(mm, addr);
|
|
if (TASK_SIZE - len >= addr &&
|
|
(!vma || addr + len <= vma->vm_start))
|
|
return addr;
|
|
}
|
|
if (len > mm->cached_hole_size) {
|
|
start_addr = addr = mm->free_area_cache;
|
|
} else {
|
|
start_addr = addr = TASK_UNMAPPED_BASE;
|
|
mm->cached_hole_size = 0;
|
|
}
|
|
|
|
full_search:
|
|
for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
|
|
/* At this point: (!vma || addr < vma->vm_end). */
|
|
if (TASK_SIZE - len < addr) {
|
|
/*
|
|
* Start a new search - just in case we missed
|
|
* some holes.
|
|
*/
|
|
if (start_addr != TASK_UNMAPPED_BASE) {
|
|
addr = TASK_UNMAPPED_BASE;
|
|
start_addr = addr;
|
|
mm->cached_hole_size = 0;
|
|
goto full_search;
|
|
}
|
|
return -ENOMEM;
|
|
}
|
|
if (!vma || addr + len <= vma->vm_start) {
|
|
/*
|
|
* Remember the place where we stopped the search:
|
|
*/
|
|
mm->free_area_cache = addr + len;
|
|
return addr;
|
|
}
|
|
if (addr + mm->cached_hole_size < vma->vm_start)
|
|
mm->cached_hole_size = vma->vm_start - addr;
|
|
addr = vma->vm_end;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
/*
|
|
* Is this a new hole at the lowest possible address?
|
|
*/
|
|
if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
|
|
mm->free_area_cache = addr;
|
|
mm->cached_hole_size = ~0UL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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, const unsigned long addr0,
|
|
const unsigned long len, const unsigned long pgoff,
|
|
const unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long addr = addr0;
|
|
|
|
/* requested length too big for entire address space */
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
/* requesting a specific address */
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma(mm, addr);
|
|
if (TASK_SIZE - len >= addr &&
|
|
(!vma || addr + len <= vma->vm_start))
|
|
return addr;
|
|
}
|
|
|
|
/* check if free_area_cache is useful for us */
|
|
if (len <= mm->cached_hole_size) {
|
|
mm->cached_hole_size = 0;
|
|
mm->free_area_cache = mm->mmap_base;
|
|
}
|
|
|
|
/* either no address requested or can't fit in requested address hole */
|
|
addr = mm->free_area_cache;
|
|
|
|
/* make sure it can fit in the remaining address space */
|
|
if (addr > len) {
|
|
vma = find_vma(mm, addr-len);
|
|
if (!vma || addr <= vma->vm_start)
|
|
/* remember the address as a hint for next time */
|
|
return (mm->free_area_cache = addr-len);
|
|
}
|
|
|
|
if (mm->mmap_base < len)
|
|
goto bottomup;
|
|
|
|
addr = mm->mmap_base-len;
|
|
|
|
do {
|
|
/*
|
|
* Lookup failure means no vma is above this address,
|
|
* else if new region fits below vma->vm_start,
|
|
* return with success:
|
|
*/
|
|
vma = find_vma(mm, addr);
|
|
if (!vma || addr+len <= vma->vm_start)
|
|
/* remember the address as a hint for next time */
|
|
return (mm->free_area_cache = addr);
|
|
|
|
/* remember the largest hole we saw so far */
|
|
if (addr + mm->cached_hole_size < vma->vm_start)
|
|
mm->cached_hole_size = vma->vm_start - addr;
|
|
|
|
/* try just below the current vma->vm_start */
|
|
addr = vma->vm_start-len;
|
|
} while (len < vma->vm_start);
|
|
|
|
bottomup:
|
|
/*
|
|
* 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.
|
|
*/
|
|
mm->cached_hole_size = ~0UL;
|
|
mm->free_area_cache = TASK_UNMAPPED_BASE;
|
|
addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
|
|
/*
|
|
* Restore the topdown base:
|
|
*/
|
|
mm->free_area_cache = mm->mmap_base;
|
|
mm->cached_hole_size = ~0UL;
|
|
|
|
return addr;
|
|
}
|
|
#endif
|
|
|
|
void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
/*
|
|
* Is this a new hole at the highest possible address?
|
|
*/
|
|
if (addr > mm->free_area_cache)
|
|
mm->free_area_cache = addr;
|
|
|
|
/* dont allow allocations above current base */
|
|
if (mm->free_area_cache > mm->mmap_base)
|
|
mm->free_area_cache = mm->mmap_base;
|
|
}
|
|
|
|
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);
|
|
|
|
get_area = current->mm->get_unmapped_area;
|
|
if (file && file->f_op && file->f_op->get_unmapped_area)
|
|
get_area = file->f_op->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 (addr & ~PAGE_MASK)
|
|
return -EINVAL;
|
|
|
|
return arch_rebalance_pgtables(addr, len);
|
|
}
|
|
|
|
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 vm_area_struct *vma = NULL;
|
|
|
|
if (mm) {
|
|
/* Check the cache first. */
|
|
/* (Cache hit rate is typically around 35%.) */
|
|
vma = mm->mmap_cache;
|
|
if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
|
|
struct rb_node * rb_node;
|
|
|
|
rb_node = mm->mm_rb.rb_node;
|
|
vma = NULL;
|
|
|
|
while (rb_node) {
|
|
struct vm_area_struct * vma_tmp;
|
|
|
|
vma_tmp = rb_entry(rb_node,
|
|
struct vm_area_struct, vm_rb);
|
|
|
|
if (vma_tmp->vm_end > addr) {
|
|
vma = vma_tmp;
|
|
if (vma_tmp->vm_start <= addr)
|
|
break;
|
|
rb_node = rb_node->rb_left;
|
|
} else
|
|
rb_node = rb_node->rb_right;
|
|
}
|
|
if (vma)
|
|
mm->mmap_cache = 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 = NULL, *prev = NULL;
|
|
struct rb_node *rb_node;
|
|
if (!mm)
|
|
goto out;
|
|
|
|
/* Guard against addr being lower than the first VMA */
|
|
vma = mm->mmap;
|
|
|
|
/* Go through the RB tree quickly. */
|
|
rb_node = mm->mm_rb.rb_node;
|
|
|
|
while (rb_node) {
|
|
struct vm_area_struct *vma_tmp;
|
|
vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
|
|
|
|
if (addr < vma_tmp->vm_end) {
|
|
rb_node = rb_node->rb_left;
|
|
} else {
|
|
prev = vma_tmp;
|
|
if (!prev->vm_next || (addr < prev->vm_next->vm_end))
|
|
break;
|
|
rb_node = rb_node->rb_right;
|
|
}
|
|
}
|
|
|
|
out:
|
|
*pprev = prev;
|
|
return prev ? prev->vm_next : 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;
|
|
struct rlimit *rlim = current->signal->rlim;
|
|
unsigned long new_start;
|
|
|
|
/* address space limit tests */
|
|
if (!may_expand_vm(mm, grow))
|
|
return -ENOMEM;
|
|
|
|
/* Stack limit test */
|
|
if (size > rlim[RLIMIT_STACK].rlim_cur)
|
|
return -ENOMEM;
|
|
|
|
/* mlock limit tests */
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
unsigned long locked;
|
|
unsigned long limit;
|
|
locked = mm->locked_vm + grow;
|
|
limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> 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;
|
|
|
|
/* Ok, everything looks good - let it rip */
|
|
mm->total_vm += grow;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
|
|
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.
|
|
*/
|
|
#ifndef CONFIG_IA64
|
|
static
|
|
#endif
|
|
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
int error;
|
|
|
|
if (!(vma->vm_flags & VM_GROWSUP))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* We must make sure the anon_vma is allocated
|
|
* so that the anon_vma locking is not a noop.
|
|
*/
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
anon_vma_lock(vma);
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_sem in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
* Also guard against wrapping around to address 0.
|
|
*/
|
|
if (address < PAGE_ALIGN(address+4))
|
|
address = PAGE_ALIGN(address+4);
|
|
else {
|
|
anon_vma_unlock(vma);
|
|
return -ENOMEM;
|
|
}
|
|
error = 0;
|
|
|
|
/* 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 = acct_stack_growth(vma, size, grow);
|
|
if (!error)
|
|
vma->vm_end = address;
|
|
}
|
|
anon_vma_unlock(vma);
|
|
return error;
|
|
}
|
|
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
|
|
|
|
/*
|
|
* vma is the first one with address < vma->vm_start. Have to extend vma.
|
|
*/
|
|
static int expand_downwards(struct vm_area_struct *vma,
|
|
unsigned long address)
|
|
{
|
|
int error;
|
|
|
|
/*
|
|
* We must make sure the anon_vma is allocated
|
|
* so that the anon_vma locking is not a noop.
|
|
*/
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
|
|
address &= PAGE_MASK;
|
|
error = security_file_mmap(NULL, 0, 0, 0, address, 1);
|
|
if (error)
|
|
return error;
|
|
|
|
anon_vma_lock(vma);
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_sem in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
|
|
/* 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 = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
vma->vm_start = address;
|
|
vma->vm_pgoff -= grow;
|
|
}
|
|
}
|
|
anon_vma_unlock(vma);
|
|
return error;
|
|
}
|
|
|
|
int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_downwards(vma, address);
|
|
}
|
|
|
|
#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;
|
|
if (!prev || expand_stack(prev, addr))
|
|
return NULL;
|
|
if (prev->vm_flags & VM_LOCKED) {
|
|
if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
|
|
return NULL; /* vma gone! */
|
|
}
|
|
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) {
|
|
if (mlock_vma_pages_range(vma, addr, start) < 0)
|
|
return NULL; /* vma gone! */
|
|
}
|
|
return vma;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
/* Update high watermark before we lower total_vm */
|
|
update_hiwater_vm(mm);
|
|
do {
|
|
long nrpages = vma_pages(vma);
|
|
|
|
mm->total_vm -= nrpages;
|
|
vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
|
|
vma = remove_vma(vma);
|
|
} while (vma);
|
|
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 = prev? prev->vm_next: mm->mmap;
|
|
struct mmu_gather *tlb;
|
|
unsigned long nr_accounted = 0;
|
|
|
|
lru_add_drain();
|
|
tlb = tlb_gather_mmu(mm, 0);
|
|
update_hiwater_rss(mm);
|
|
unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
|
|
vm_unacct_memory(nr_accounted);
|
|
free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
|
|
next? next->vm_start: 0);
|
|
tlb_finish_mmu(tlb, start, end);
|
|
}
|
|
|
|
/*
|
|
* Create a list of vma's touched by the unmap, removing them from the mm's
|
|
* vma list as we go..
|
|
*/
|
|
static void
|
|
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;
|
|
unsigned long addr;
|
|
|
|
insertion_point = (prev ? &prev->vm_next : &mm->mmap);
|
|
do {
|
|
rb_erase(&vma->vm_rb, &mm->mm_rb);
|
|
mm->map_count--;
|
|
tail_vma = vma;
|
|
vma = vma->vm_next;
|
|
} while (vma && vma->vm_start < end);
|
|
*insertion_point = vma;
|
|
tail_vma->vm_next = NULL;
|
|
if (mm->unmap_area == arch_unmap_area)
|
|
addr = prev ? prev->vm_end : mm->mmap_base;
|
|
else
|
|
addr = vma ? vma->vm_start : mm->mmap_base;
|
|
mm->unmap_area(mm, addr);
|
|
mm->mmap_cache = NULL; /* Kill the cache. */
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct mempolicy *pol;
|
|
struct vm_area_struct *new;
|
|
|
|
if (is_vm_hugetlb_page(vma) && (addr &
|
|
~(huge_page_mask(hstate_vma(vma)))))
|
|
return -EINVAL;
|
|
|
|
if (mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
/* most fields are the same, copy all, and then fixup */
|
|
*new = *vma;
|
|
|
|
if (new_below)
|
|
new->vm_end = addr;
|
|
else {
|
|
new->vm_start = addr;
|
|
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
pol = mpol_dup(vma_policy(vma));
|
|
if (IS_ERR(pol)) {
|
|
kmem_cache_free(vm_area_cachep, new);
|
|
return PTR_ERR(pol);
|
|
}
|
|
vma_set_policy(new, pol);
|
|
|
|
if (new->vm_file) {
|
|
get_file(new->vm_file);
|
|
if (vma->vm_flags & VM_EXECUTABLE)
|
|
added_exe_file_vma(mm);
|
|
}
|
|
|
|
if (new->vm_ops && new->vm_ops->open)
|
|
new->vm_ops->open(new);
|
|
|
|
if (new_below)
|
|
vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
|
|
((addr - new->vm_start) >> PAGE_SHIFT), new);
|
|
else
|
|
vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* 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)
|
|
{
|
|
unsigned long end;
|
|
struct vm_area_struct *vma, *prev, *last;
|
|
|
|
if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
|
|
return -EINVAL;
|
|
|
|
if ((len = PAGE_ALIGN(len)) == 0)
|
|
return -EINVAL;
|
|
|
|
/* Find the first overlapping VMA */
|
|
vma = find_vma_prev(mm, start, &prev);
|
|
if (!vma)
|
|
return 0;
|
|
/* we have start < vma->vm_end */
|
|
|
|
/* if it doesn't overlap, we have nothing.. */
|
|
end = start + len;
|
|
if (vma->vm_start >= end)
|
|
return 0;
|
|
|
|
/*
|
|
* 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 = 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 = prev? prev->vm_next: mm->mmap;
|
|
|
|
/*
|
|
* unlock any mlock()ed ranges before detaching vmas
|
|
*/
|
|
if (mm->locked_vm) {
|
|
struct vm_area_struct *tmp = vma;
|
|
while (tmp && tmp->vm_start < end) {
|
|
if (tmp->vm_flags & VM_LOCKED) {
|
|
mm->locked_vm -= vma_pages(tmp);
|
|
munlock_vma_pages_all(tmp);
|
|
}
|
|
tmp = tmp->vm_next;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Remove the vma's, and unmap the actual pages
|
|
*/
|
|
detach_vmas_to_be_unmapped(mm, vma, prev, end);
|
|
unmap_region(mm, vma, prev, start, end);
|
|
|
|
/* Fix up all other VM information */
|
|
remove_vma_list(mm, vma);
|
|
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(do_munmap);
|
|
|
|
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
|
|
{
|
|
int ret;
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
profile_munmap(addr);
|
|
|
|
down_write(&mm->mmap_sem);
|
|
ret = do_munmap(mm, addr, len);
|
|
up_write(&mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
static inline void verify_mm_writelocked(struct mm_struct *mm)
|
|
{
|
|
#ifdef CONFIG_DEBUG_VM
|
|
if (unlikely(down_read_trylock(&mm->mmap_sem))) {
|
|
WARN_ON(1);
|
|
up_read(&mm->mmap_sem);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* this is really a simplified "do_mmap". it only handles
|
|
* anonymous maps. eventually we may be able to do some
|
|
* brk-specific accounting here.
|
|
*/
|
|
unsigned long do_brk(unsigned long addr, unsigned long len)
|
|
{
|
|
struct mm_struct * mm = current->mm;
|
|
struct vm_area_struct * vma, * prev;
|
|
unsigned long flags;
|
|
struct rb_node ** rb_link, * rb_parent;
|
|
pgoff_t pgoff = addr >> PAGE_SHIFT;
|
|
int error;
|
|
|
|
len = PAGE_ALIGN(len);
|
|
if (!len)
|
|
return addr;
|
|
|
|
if ((addr + len) > TASK_SIZE || (addr + len) < addr)
|
|
return -EINVAL;
|
|
|
|
if (is_hugepage_only_range(mm, addr, len))
|
|
return -EINVAL;
|
|
|
|
error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
|
|
if (error)
|
|
return error;
|
|
|
|
flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
|
|
|
|
error = arch_mmap_check(addr, len, flags);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* mlock MCL_FUTURE?
|
|
*/
|
|
if (mm->def_flags & VM_LOCKED) {
|
|
unsigned long locked, lock_limit;
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += mm->locked_vm;
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
|
|
return -EAGAIN;
|
|
}
|
|
|
|
/*
|
|
* mm->mmap_sem is required to protect against another thread
|
|
* changing the mappings in case we sleep.
|
|
*/
|
|
verify_mm_writelocked(mm);
|
|
|
|
/*
|
|
* Clear old maps. this also does some error checking for us
|
|
*/
|
|
munmap_back:
|
|
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
|
|
if (vma && vma->vm_start < addr + len) {
|
|
if (do_munmap(mm, addr, len))
|
|
return -ENOMEM;
|
|
goto munmap_back;
|
|
}
|
|
|
|
/* Check against address space limits *after* clearing old maps... */
|
|
if (!may_expand_vm(mm, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
if (security_vm_enough_memory(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);
|
|
if (vma)
|
|
goto out;
|
|
|
|
/*
|
|
* create a vma struct for an anonymous mapping
|
|
*/
|
|
vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
|
|
if (!vma) {
|
|
vm_unacct_memory(len >> PAGE_SHIFT);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
vma->vm_mm = mm;
|
|
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:
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
if (flags & VM_LOCKED) {
|
|
if (!mlock_vma_pages_range(vma, addr, addr + len))
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
}
|
|
return addr;
|
|
}
|
|
|
|
EXPORT_SYMBOL(do_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;
|
|
unsigned long end;
|
|
|
|
/* mm's last user has gone, and its about to be pulled down */
|
|
mmu_notifier_release(mm);
|
|
|
|
if (mm->locked_vm) {
|
|
vma = mm->mmap;
|
|
while (vma) {
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
munlock_vma_pages_all(vma);
|
|
vma = vma->vm_next;
|
|
}
|
|
}
|
|
|
|
arch_exit_mmap(mm);
|
|
|
|
vma = mm->mmap;
|
|
if (!vma) /* Can happen if dup_mmap() received an OOM */
|
|
return;
|
|
|
|
lru_add_drain();
|
|
flush_cache_mm(mm);
|
|
tlb = tlb_gather_mmu(mm, 1);
|
|
/* update_hiwater_rss(mm) here? but nobody should be looking */
|
|
/* Use -1 here to ensure all VMAs in the mm are unmapped */
|
|
end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
|
|
vm_unacct_memory(nr_accounted);
|
|
free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
|
|
tlb_finish_mmu(tlb, 0, end);
|
|
|
|
/*
|
|
* Walk the list again, actually closing and freeing it,
|
|
* with preemption enabled, without holding any MM locks.
|
|
*/
|
|
while (vma)
|
|
vma = remove_vma(vma);
|
|
|
|
BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
|
|
}
|
|
|
|
/* 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_lock is taken here.
|
|
*/
|
|
int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
|
|
{
|
|
struct vm_area_struct * __vma, * prev;
|
|
struct rb_node ** rb_link, * rb_parent;
|
|
|
|
/*
|
|
* 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_pgoff and in do_brk.
|
|
*/
|
|
if (!vma->vm_file) {
|
|
BUG_ON(vma->anon_vma);
|
|
vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
|
|
}
|
|
__vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
|
|
if (__vma && __vma->vm_start < vma->vm_end)
|
|
return -ENOMEM;
|
|
if ((vma->vm_flags & VM_ACCOUNT) &&
|
|
security_vm_enough_memory_mm(mm, vma_pages(vma)))
|
|
return -ENOMEM;
|
|
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)
|
|
{
|
|
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;
|
|
struct mempolicy *pol;
|
|
|
|
/*
|
|
* If anonymous vma has not yet been faulted, update new pgoff
|
|
* to match new location, to increase its chance of merging.
|
|
*/
|
|
if (!vma->vm_file && !vma->anon_vma)
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
|
|
find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
|
|
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
|
|
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
|
|
if (new_vma) {
|
|
/*
|
|
* Source vma may have been merged into new_vma
|
|
*/
|
|
if (vma_start >= new_vma->vm_start &&
|
|
vma_start < new_vma->vm_end)
|
|
*vmap = new_vma;
|
|
} else {
|
|
new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
|
|
if (new_vma) {
|
|
*new_vma = *vma;
|
|
pol = mpol_dup(vma_policy(vma));
|
|
if (IS_ERR(pol)) {
|
|
kmem_cache_free(vm_area_cachep, new_vma);
|
|
return NULL;
|
|
}
|
|
vma_set_policy(new_vma, pol);
|
|
new_vma->vm_start = addr;
|
|
new_vma->vm_end = addr + len;
|
|
new_vma->vm_pgoff = pgoff;
|
|
if (new_vma->vm_file) {
|
|
get_file(new_vma->vm_file);
|
|
if (vma->vm_flags & VM_EXECUTABLE)
|
|
added_exe_file_vma(mm);
|
|
}
|
|
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);
|
|
}
|
|
}
|
|
return new_vma;
|
|
}
|
|
|
|
/*
|
|
* Return true if the calling process may expand its vm space by the passed
|
|
* number of pages
|
|
*/
|
|
int may_expand_vm(struct mm_struct *mm, unsigned long npages)
|
|
{
|
|
unsigned long cur = mm->total_vm; /* pages */
|
|
unsigned long lim;
|
|
|
|
lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
|
|
|
|
if (cur + npages > lim)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
|
|
static int special_mapping_fault(struct vm_area_struct *vma,
|
|
struct vm_fault *vmf)
|
|
{
|
|
pgoff_t pgoff;
|
|
struct page **pages;
|
|
|
|
/*
|
|
* special mappings have no vm_file, and in that case, the mm
|
|
* uses vm_pgoff internally. So we have to subtract it from here.
|
|
* We are allowed to do this because we are the mm; do not copy
|
|
* this code into drivers!
|
|
*/
|
|
pgoff = vmf->pgoff - vma->vm_pgoff;
|
|
|
|
for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
|
|
pgoff--;
|
|
|
|
if (*pages) {
|
|
struct page *page = *pages;
|
|
get_page(page);
|
|
vmf->page = page;
|
|
return 0;
|
|
}
|
|
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
/*
|
|
* Having a close hook prevents vma merging regardless of flags.
|
|
*/
|
|
static void special_mapping_close(struct vm_area_struct *vma)
|
|
{
|
|
}
|
|
|
|
static struct vm_operations_struct special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
};
|
|
|
|
/*
|
|
* Called with mm->mmap_sem 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.
|
|
*/
|
|
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;
|
|
|
|
vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
|
|
if (unlikely(vma == NULL))
|
|
return -ENOMEM;
|
|
|
|
vma->vm_mm = mm;
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
|
|
vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
|
|
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
|
|
|
|
vma->vm_ops = &special_mapping_vmops;
|
|
vma->vm_private_data = pages;
|
|
|
|
if (unlikely(insert_vm_struct(mm, vma))) {
|
|
kmem_cache_free(vm_area_cachep, vma);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
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->head.next)) {
|
|
/*
|
|
* The LSB of head.next can't change from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
|
|
/*
|
|
* We can safely modify head.next after taking the
|
|
* anon_vma->lock. 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->lock.
|
|
*/
|
|
if (__test_and_set_bit(0, (unsigned long *)
|
|
&anon_vma->head.next))
|
|
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();
|
|
spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_sem in write mode before calling
|
|
* mm_take_all_locks(). The caller isn't allowed to release the
|
|
* mmap_sem until mm_drop_all_locks() returns.
|
|
*
|
|
* mmap_sem 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 (for example populate_range() with
|
|
* nonlinear vmas). 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->head.next 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 can take all the locks in random order because the VM code
|
|
* taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
|
|
* takes more than one of them in a row. Secondly we're protected
|
|
* against a concurrent mm_take_all_locks() by the 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;
|
|
int ret = -EINTR;
|
|
|
|
BUG_ON(down_read_trylock(&mm->mmap_sem));
|
|
|
|
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)
|
|
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)
|
|
vm_lock_anon_vma(mm, vma->anon_vma);
|
|
}
|
|
|
|
ret = 0;
|
|
|
|
out_unlock:
|
|
if (ret)
|
|
mm_drop_all_locks(mm);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
|
|
{
|
|
if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
|
|
/*
|
|
* 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->head 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->lock.
|
|
*/
|
|
if (!__test_and_clear_bit(0, (unsigned long *)
|
|
&anon_vma->head.next))
|
|
BUG();
|
|
spin_unlock(&anon_vma->lock);
|
|
}
|
|
}
|
|
|
|
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.
|
|
*/
|
|
spin_unlock(&mapping->i_mmap_lock);
|
|
if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
|
|
&mapping->flags))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The mmap_sem 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;
|
|
|
|
BUG_ON(down_read_trylock(&mm->mmap_sem));
|
|
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (vma->anon_vma)
|
|
vm_unlock_anon_vma(vma->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 VMA slab
|
|
*/
|
|
void __init mmap_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = percpu_counter_init(&vm_committed_as, 0);
|
|
VM_BUG_ON(ret);
|
|
}
|