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35010334aa
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, vm86: fix preemption bug x86, olpc: fix model detection without OFW x86, hpet: fix for LS21 + HPET = boot hang x86: CPA avoid repeated lazy mmu flush x86: warn if arch_flush_lazy_mmu_cpu is called in preemptible context x86/paravirt: make arch_flush_lazy_mmu/cpu disable preemption x86, pat: fix warn_on_once() while mapping 0-1MB range with /dev/mem x86/cpa: make sure cpa is safe to call in lazy mmu mode x86, ptrace, mm: fix double-free on race
681 lines
17 KiB
C
681 lines
17 KiB
C
/*
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* linux/mm/mlock.c
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*
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* (C) Copyright 1995 Linus Torvalds
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* (C) Copyright 2002 Christoph Hellwig
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*/
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#include <linux/capability.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pagemap.h>
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#include <linux/mempolicy.h>
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#include <linux/syscalls.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/rmap.h>
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#include <linux/mmzone.h>
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#include <linux/hugetlb.h>
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#include "internal.h"
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int can_do_mlock(void)
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{
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if (capable(CAP_IPC_LOCK))
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return 1;
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if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
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return 1;
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return 0;
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}
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EXPORT_SYMBOL(can_do_mlock);
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#ifdef CONFIG_UNEVICTABLE_LRU
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/*
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* Mlocked pages are marked with PageMlocked() flag for efficient testing
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* in vmscan and, possibly, the fault path; and to support semi-accurate
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* statistics.
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*
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* An mlocked page [PageMlocked(page)] is unevictable. As such, it will
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* be placed on the LRU "unevictable" list, rather than the [in]active lists.
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* The unevictable list is an LRU sibling list to the [in]active lists.
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* PageUnevictable is set to indicate the unevictable state.
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*
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* When lazy mlocking via vmscan, it is important to ensure that the
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* vma's VM_LOCKED status is not concurrently being modified, otherwise we
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* may have mlocked a page that is being munlocked. So lazy mlock must take
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* the mmap_sem for read, and verify that the vma really is locked
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* (see mm/rmap.c).
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*/
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/*
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* LRU accounting for clear_page_mlock()
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*/
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void __clear_page_mlock(struct page *page)
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{
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VM_BUG_ON(!PageLocked(page));
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if (!page->mapping) { /* truncated ? */
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return;
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}
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dec_zone_page_state(page, NR_MLOCK);
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count_vm_event(UNEVICTABLE_PGCLEARED);
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if (!isolate_lru_page(page)) {
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putback_lru_page(page);
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} else {
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/*
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* We lost the race. the page already moved to evictable list.
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*/
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if (PageUnevictable(page))
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count_vm_event(UNEVICTABLE_PGSTRANDED);
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}
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}
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/*
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* Mark page as mlocked if not already.
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* If page on LRU, isolate and putback to move to unevictable list.
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*/
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void mlock_vma_page(struct page *page)
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{
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BUG_ON(!PageLocked(page));
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if (!TestSetPageMlocked(page)) {
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inc_zone_page_state(page, NR_MLOCK);
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count_vm_event(UNEVICTABLE_PGMLOCKED);
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if (!isolate_lru_page(page))
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putback_lru_page(page);
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}
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}
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/*
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* called from munlock()/munmap() path with page supposedly on the LRU.
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*
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* Note: unlike mlock_vma_page(), we can't just clear the PageMlocked
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* [in try_to_munlock()] and then attempt to isolate the page. We must
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* isolate the page to keep others from messing with its unevictable
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* and mlocked state while trying to munlock. However, we pre-clear the
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* mlocked state anyway as we might lose the isolation race and we might
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* not get another chance to clear PageMlocked. If we successfully
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* isolate the page and try_to_munlock() detects other VM_LOCKED vmas
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* mapping the page, it will restore the PageMlocked state, unless the page
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* is mapped in a non-linear vma. So, we go ahead and SetPageMlocked(),
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* perhaps redundantly.
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* If we lose the isolation race, and the page is mapped by other VM_LOCKED
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* vmas, we'll detect this in vmscan--via try_to_munlock() or try_to_unmap()
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* either of which will restore the PageMlocked state by calling
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* mlock_vma_page() above, if it can grab the vma's mmap sem.
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*/
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static void munlock_vma_page(struct page *page)
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{
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BUG_ON(!PageLocked(page));
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if (TestClearPageMlocked(page)) {
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dec_zone_page_state(page, NR_MLOCK);
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if (!isolate_lru_page(page)) {
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int ret = try_to_munlock(page);
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/*
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* did try_to_unlock() succeed or punt?
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*/
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if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
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count_vm_event(UNEVICTABLE_PGMUNLOCKED);
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putback_lru_page(page);
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} else {
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/*
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* We lost the race. let try_to_unmap() deal
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* with it. At least we get the page state and
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* mlock stats right. However, page is still on
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* the noreclaim list. We'll fix that up when
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* the page is eventually freed or we scan the
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* noreclaim list.
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*/
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if (PageUnevictable(page))
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count_vm_event(UNEVICTABLE_PGSTRANDED);
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else
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count_vm_event(UNEVICTABLE_PGMUNLOCKED);
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}
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}
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}
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/**
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* __mlock_vma_pages_range() - mlock/munlock a range of pages in the vma.
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* @vma: target vma
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* @start: start address
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* @end: end address
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* @mlock: 0 indicate munlock, otherwise mlock.
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*
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* If @mlock == 0, unlock an mlocked range;
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* else mlock the range of pages. This takes care of making the pages present ,
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* too.
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*
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* return 0 on success, negative error code on error.
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*
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* vma->vm_mm->mmap_sem must be held for at least read.
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*/
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static long __mlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end,
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int mlock)
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{
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struct mm_struct *mm = vma->vm_mm;
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unsigned long addr = start;
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struct page *pages[16]; /* 16 gives a reasonable batch */
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int nr_pages = (end - start) / PAGE_SIZE;
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int ret = 0;
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int gup_flags = 0;
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VM_BUG_ON(start & ~PAGE_MASK);
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VM_BUG_ON(end & ~PAGE_MASK);
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VM_BUG_ON(start < vma->vm_start);
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VM_BUG_ON(end > vma->vm_end);
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VM_BUG_ON((!rwsem_is_locked(&mm->mmap_sem)) &&
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(atomic_read(&mm->mm_users) != 0));
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/*
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* mlock: don't page populate if vma has PROT_NONE permission.
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* munlock: always do munlock although the vma has PROT_NONE
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* permission, or SIGKILL is pending.
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*/
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if (!mlock)
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gup_flags |= GUP_FLAGS_IGNORE_VMA_PERMISSIONS |
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GUP_FLAGS_IGNORE_SIGKILL;
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if (vma->vm_flags & VM_WRITE)
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gup_flags |= GUP_FLAGS_WRITE;
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while (nr_pages > 0) {
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int i;
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cond_resched();
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/*
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* get_user_pages makes pages present if we are
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* setting mlock. and this extra reference count will
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* disable migration of this page. However, page may
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* still be truncated out from under us.
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*/
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ret = __get_user_pages(current, mm, addr,
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min_t(int, nr_pages, ARRAY_SIZE(pages)),
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gup_flags, pages, NULL);
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/*
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* This can happen for, e.g., VM_NONLINEAR regions before
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* a page has been allocated and mapped at a given offset,
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* or for addresses that map beyond end of a file.
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* We'll mlock the the pages if/when they get faulted in.
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*/
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if (ret < 0)
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break;
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if (ret == 0) {
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/*
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* We know the vma is there, so the only time
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* we cannot get a single page should be an
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* error (ret < 0) case.
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*/
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WARN_ON(1);
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break;
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}
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lru_add_drain(); /* push cached pages to LRU */
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for (i = 0; i < ret; i++) {
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struct page *page = pages[i];
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lock_page(page);
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/*
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* Because we lock page here and migration is blocked
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* by the elevated reference, we need only check for
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* page truncation (file-cache only).
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*/
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if (page->mapping) {
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if (mlock)
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mlock_vma_page(page);
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else
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munlock_vma_page(page);
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}
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unlock_page(page);
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put_page(page); /* ref from get_user_pages() */
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/*
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* here we assume that get_user_pages() has given us
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* a list of virtually contiguous pages.
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*/
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addr += PAGE_SIZE; /* for next get_user_pages() */
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nr_pages--;
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}
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ret = 0;
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}
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return ret; /* count entire vma as locked_vm */
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}
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/*
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* convert get_user_pages() return value to posix mlock() error
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*/
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static int __mlock_posix_error_return(long retval)
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{
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if (retval == -EFAULT)
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retval = -ENOMEM;
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else if (retval == -ENOMEM)
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retval = -EAGAIN;
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return retval;
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}
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#else /* CONFIG_UNEVICTABLE_LRU */
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/*
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* Just make pages present if VM_LOCKED. No-op if unlocking.
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*/
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static long __mlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end,
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int mlock)
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{
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if (mlock && (vma->vm_flags & VM_LOCKED))
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return make_pages_present(start, end);
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return 0;
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}
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static inline int __mlock_posix_error_return(long retval)
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{
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return 0;
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}
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#endif /* CONFIG_UNEVICTABLE_LRU */
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/**
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* mlock_vma_pages_range() - mlock pages in specified vma range.
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* @vma - the vma containing the specfied address range
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* @start - starting address in @vma to mlock
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* @end - end address [+1] in @vma to mlock
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*
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* For mmap()/mremap()/expansion of mlocked vma.
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*
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* return 0 on success for "normal" vmas.
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*
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* return number of pages [> 0] to be removed from locked_vm on success
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* of "special" vmas.
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*/
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long mlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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int nr_pages = (end - start) / PAGE_SIZE;
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BUG_ON(!(vma->vm_flags & VM_LOCKED));
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/*
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* filter unlockable vmas
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*/
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if (vma->vm_flags & (VM_IO | VM_PFNMAP))
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goto no_mlock;
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if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
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is_vm_hugetlb_page(vma) ||
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vma == get_gate_vma(current))) {
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__mlock_vma_pages_range(vma, start, end, 1);
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/* Hide errors from mmap() and other callers */
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return 0;
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}
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/*
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* User mapped kernel pages or huge pages:
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* make these pages present to populate the ptes, but
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* fall thru' to reset VM_LOCKED--no need to unlock, and
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* return nr_pages so these don't get counted against task's
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* locked limit. huge pages are already counted against
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* locked vm limit.
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*/
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make_pages_present(start, end);
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no_mlock:
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vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
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return nr_pages; /* error or pages NOT mlocked */
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}
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/*
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* munlock_vma_pages_range() - munlock all pages in the vma range.'
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* @vma - vma containing range to be munlock()ed.
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* @start - start address in @vma of the range
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* @end - end of range in @vma.
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*
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* For mremap(), munmap() and exit().
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*
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* Called with @vma VM_LOCKED.
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*
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* Returns with VM_LOCKED cleared. Callers must be prepared to
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* deal with this.
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*
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* We don't save and restore VM_LOCKED here because pages are
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* still on lru. In unmap path, pages might be scanned by reclaim
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* and re-mlocked by try_to_{munlock|unmap} before we unmap and
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* free them. This will result in freeing mlocked pages.
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*/
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void munlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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vma->vm_flags &= ~VM_LOCKED;
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__mlock_vma_pages_range(vma, start, end, 0);
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}
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/*
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* mlock_fixup - handle mlock[all]/munlock[all] requests.
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*
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* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
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* munlock is a no-op. However, for some special vmas, we go ahead and
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* populate the ptes via make_pages_present().
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*
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* For vmas that pass the filters, merge/split as appropriate.
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*/
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static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
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unsigned long start, unsigned long end, unsigned int newflags)
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{
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struct mm_struct *mm = vma->vm_mm;
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pgoff_t pgoff;
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int nr_pages;
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int ret = 0;
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int lock = newflags & VM_LOCKED;
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if (newflags == vma->vm_flags ||
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(vma->vm_flags & (VM_IO | VM_PFNMAP)))
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goto out; /* don't set VM_LOCKED, don't count */
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if ((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
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is_vm_hugetlb_page(vma) ||
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vma == get_gate_vma(current)) {
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if (lock)
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make_pages_present(start, end);
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goto out; /* don't set VM_LOCKED, don't count */
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}
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pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
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*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
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vma->vm_file, pgoff, vma_policy(vma));
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if (*prev) {
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vma = *prev;
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goto success;
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}
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if (start != vma->vm_start) {
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ret = split_vma(mm, vma, start, 1);
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if (ret)
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goto out;
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}
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if (end != vma->vm_end) {
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ret = split_vma(mm, vma, end, 0);
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if (ret)
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goto out;
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}
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success:
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/*
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* Keep track of amount of locked VM.
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*/
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nr_pages = (end - start) >> PAGE_SHIFT;
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if (!lock)
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nr_pages = -nr_pages;
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mm->locked_vm += nr_pages;
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/*
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* vm_flags is protected by the mmap_sem held in write mode.
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* It's okay if try_to_unmap_one unmaps a page just after we
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* set VM_LOCKED, __mlock_vma_pages_range will bring it back.
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*/
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vma->vm_flags = newflags;
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if (lock) {
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ret = __mlock_vma_pages_range(vma, start, end, 1);
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if (ret > 0) {
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mm->locked_vm -= ret;
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ret = 0;
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} else
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ret = __mlock_posix_error_return(ret); /* translate if needed */
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} else {
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__mlock_vma_pages_range(vma, start, end, 0);
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}
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out:
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*prev = vma;
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return ret;
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}
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static int do_mlock(unsigned long start, size_t len, int on)
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{
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unsigned long nstart, end, tmp;
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struct vm_area_struct * vma, * prev;
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int error;
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len = PAGE_ALIGN(len);
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end = start + len;
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if (end < start)
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return -EINVAL;
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if (end == start)
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return 0;
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vma = find_vma_prev(current->mm, start, &prev);
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if (!vma || vma->vm_start > start)
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return -ENOMEM;
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if (start > vma->vm_start)
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prev = vma;
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for (nstart = start ; ; ) {
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unsigned int newflags;
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/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
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newflags = vma->vm_flags | VM_LOCKED;
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if (!on)
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newflags &= ~VM_LOCKED;
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tmp = vma->vm_end;
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if (tmp > end)
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tmp = end;
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error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
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if (error)
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break;
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nstart = tmp;
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if (nstart < prev->vm_end)
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nstart = prev->vm_end;
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if (nstart >= end)
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break;
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vma = prev->vm_next;
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if (!vma || vma->vm_start != nstart) {
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error = -ENOMEM;
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break;
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}
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}
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return error;
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}
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SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
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{
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unsigned long locked;
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unsigned long lock_limit;
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int error = -ENOMEM;
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|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += current->mm->locked_vm;
|
|
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
|
|
/* check against resource limits */
|
|
if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
|
|
error = do_mlock(start, len, 1);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
ret = do_mlock(start, len, 0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
static int do_mlockall(int flags)
|
|
{
|
|
struct vm_area_struct * vma, * prev = NULL;
|
|
unsigned int def_flags = 0;
|
|
|
|
if (flags & MCL_FUTURE)
|
|
def_flags = VM_LOCKED;
|
|
current->mm->def_flags = def_flags;
|
|
if (flags == MCL_FUTURE)
|
|
goto out;
|
|
|
|
for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
|
|
unsigned int newflags;
|
|
|
|
newflags = vma->vm_flags | VM_LOCKED;
|
|
if (!(flags & MCL_CURRENT))
|
|
newflags &= ~VM_LOCKED;
|
|
|
|
/* Ignore errors */
|
|
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
|
|
}
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(mlockall, int, flags)
|
|
{
|
|
unsigned long lock_limit;
|
|
int ret = -EINVAL;
|
|
|
|
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
|
|
goto out;
|
|
|
|
ret = -EPERM;
|
|
if (!can_do_mlock())
|
|
goto out;
|
|
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
|
|
ret = -ENOMEM;
|
|
if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
|
|
capable(CAP_IPC_LOCK))
|
|
ret = do_mlockall(flags);
|
|
up_write(¤t->mm->mmap_sem);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(munlockall)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = do_mlockall(0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
|
|
* shm segments) get accounted against the user_struct instead.
|
|
*/
|
|
static DEFINE_SPINLOCK(shmlock_user_lock);
|
|
|
|
int user_shm_lock(size_t size, struct user_struct *user)
|
|
{
|
|
unsigned long lock_limit, locked;
|
|
int allowed = 0;
|
|
|
|
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
|
|
if (lock_limit == RLIM_INFINITY)
|
|
allowed = 1;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
spin_lock(&shmlock_user_lock);
|
|
if (!allowed &&
|
|
locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
|
|
goto out;
|
|
get_uid(user);
|
|
user->locked_shm += locked;
|
|
allowed = 1;
|
|
out:
|
|
spin_unlock(&shmlock_user_lock);
|
|
return allowed;
|
|
}
|
|
|
|
void user_shm_unlock(size_t size, struct user_struct *user)
|
|
{
|
|
spin_lock(&shmlock_user_lock);
|
|
user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
spin_unlock(&shmlock_user_lock);
|
|
free_uid(user);
|
|
}
|
|
|
|
void *alloc_locked_buffer(size_t size)
|
|
{
|
|
unsigned long rlim, vm, pgsz;
|
|
void *buffer = NULL;
|
|
|
|
pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
rlim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
|
|
vm = current->mm->total_vm + pgsz;
|
|
if (rlim < vm)
|
|
goto out;
|
|
|
|
rlim = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
|
|
vm = current->mm->locked_vm + pgsz;
|
|
if (rlim < vm)
|
|
goto out;
|
|
|
|
buffer = kzalloc(size, GFP_KERNEL);
|
|
if (!buffer)
|
|
goto out;
|
|
|
|
current->mm->total_vm += pgsz;
|
|
current->mm->locked_vm += pgsz;
|
|
|
|
out:
|
|
up_write(¤t->mm->mmap_sem);
|
|
return buffer;
|
|
}
|
|
|
|
void release_locked_buffer(void *buffer, size_t size)
|
|
{
|
|
unsigned long pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
current->mm->total_vm -= pgsz;
|
|
current->mm->locked_vm -= pgsz;
|
|
|
|
up_write(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
void free_locked_buffer(void *buffer, size_t size)
|
|
{
|
|
release_locked_buffer(buffer, size);
|
|
|
|
kfree(buffer);
|
|
}
|