The patch titled
mlock: update locked_vm on munmap() of mlocked() region.
has been added to the -mm tree. Its filename is
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region.patch
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------------------------------------------------------
Subject: mlock: update locked_vm on munmap() of mlocked() region.
From: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
munlock_vma_pages_range() clears VM_LOCKED for munlock_vma_page(), et al
to work. This causes remove_vma_list(), called from do_munmap(), to skip
updating locked_vm.
We don't want to restore the VM_LOCKED in munlock_vma_pages_range()
because the pages are still on the lru. If vmscan attempts to reclaim
any of these pages before we get a chance to unmap them,
try_to_un{lock|map}() may mlock them again. This will result in freeing
an mlocked page.
Add comment block to munlock_vma_pages_range() to explain
this to future would be callers.
Move the accounting of locked_vm from remove_vma_list() to the munlock
loop in do_munmap(). This is where the pages are munlocked and VM_LOCKED
is cleared. Note that remove_vma_list() is a helper function for
do_munmap(), called only from there.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mlock.c | 17 ++++++++++++++++-
mm/mmap.c | 6 +++---
2 files changed, 19 insertions(+), 4 deletions(-)
diff -puN mm/mlock.c~mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region mm/mlock.c
--- a/mm/mlock.c~mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region
+++ a/mm/mlock.c
@@ -305,7 +305,22 @@ no_mlock:
/*
- * munlock all pages in the vma range. For mremap(), munmap() and exit().
+ * munlock_vma_pages_range() - munlock all pages in the vma range.'
+ * @vma - vma containing range to be munlock()ed.
+ * @start - start address in @vma of the range
+ * @end - end of range in @vma.
+ *
+ * For mremap(), munmap() and exit().
+ *
+ * Called with @vma VM_LOCKED.
+ *
+ * Returns with VM_LOCKED cleared. Callers must be prepared to
+ * deal with this.
+ *
+ * We don't save and restore VM_LOCKED here because pages are
+ * still on lru. In unmap path, pages might be scanned by reclaim
+ * and re-mlocked by try_to_{munlock|unmap} before we unmap and
+ * free them. This will result in freeing mlocked pages.
*/
void munlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
diff -puN mm/mmap.c~mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region mm/mmap.c
--- a/mm/mmap.c~mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region
+++ a/mm/mmap.c
@@ -1752,8 +1752,6 @@ static void remove_vma_list(struct mm_st
long nrpages = vma_pages(vma);
mm->total_vm -= nrpages;
- if (vma->vm_flags & VM_LOCKED)
- mm->locked_vm -= nrpages;
vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
vma = remove_vma(vma);
} while (vma);
@@ -1924,8 +1922,10 @@ int do_munmap(struct mm_struct *mm, unsi
if (mm->locked_vm) {
struct vm_area_struct *tmp = vma;
while (tmp && tmp->vm_start < end) {
- if (tmp->vm_flags & VM_LOCKED)
+ if (tmp->vm_flags & VM_LOCKED) {
+ mm->locked_vm -= vma_pages(tmp);
munlock_vma_pages_all(tmp);
+ }
tmp = tmp->vm_next;
}
}
_
Patches currently in -mm which might be from lee.schermerhorn@xxxxxx are
vmscan-use-an-indexed-array-for-lru-variables.patch
define-page_file_cache-function.patch
vmscan-split-lru-lists-into-anon-file-sets.patch
pageflag-helpers-for-configed-out-flags.patch
unevictable-lru-infrastructure.patch
unevictable-lru-infrastructure-nommu-fix.patch
unevictable-lru-infrastructure-remember-pages-active-state.patch
unevictable-lru-infrastructure-defer-vm-event-counting.patch
unevictable-infrastructure-lru-add-event-counting-with-statistics.patch
unevictable-lru-page-statistics.patch
ramfs-and-ram-disk-pages-are-unevictable.patch
shm_locked-pages-are-unevictable.patch
shm_locked-pages-are-unevictable-add-event-counts-to-list-scan.patch
mlock-mlocked-pages-are-unevictable.patch
mlock-mlocked-pages-are-unevictable-fix.patch
doc-unevictable-lru-and-mlocked-pages-documentation.patch
doc-unevictable-lru-and-mlocked-pages-documentation-update.patch
doc-unevictable-lru-and-mlocked-pages-documentation-update-2.patch
mlock-downgrade-mmap-sem-while-populating-mlocked-regions.patch
mmap-handle-mlocked-pages-during-map-remap-unmap.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-fix-__mlock_vma_pages_range-comment-block.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-backout-locked_vm-adjustment-during-mmap.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-resubmit-locked_vm-adjustment-as-separate-patch.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-fix-return-value-for-munmap-mlock-vma-race.patch
mmap-handle-mlocked-pages-during-map-remap-unmap-mlock-update-locked_vm-on-munmap-of-mlocked-region.patch
vmstat-mlocked-pages-statistics.patch
vmstat-mlocked-pages-statistics-mlocked-pages-add-event-counting-with-statistics.patch
swap-cull-unevictable-pages-in-fault-path.patch
vmscan-unevictable-lru-scan-sysctl.patch
mlock-count-attempts-to-free-mlocked-page-2.patch
mlock-revert-mainline-handling-of-mlock-error-return.patch
mlock-make-mlock-error-return-posixly-correct.patch
--
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