The patch titled
Subject: mm: fix the racy mm->locked_vm change in
has been added to the -mm tree. Its filename is
mm-fix-the-racy-mm-locked_vm-change-in.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-the-racy-mm-locked_vm-change-in.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-the-racy-mm-locked_vm-change-in.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: mm: fix the racy mm->locked_vm change in
"mm->locked_vm += grow" and vm_stat_account() in acct_stack_growth() are
not safe; multiple threads using the same ->mm can do this at the same
time trying to expans different vma's under down_read(mmap_sem). This
means that one of the "locked_vm += grow" changes can be lost and we can
miss munlock_vma_pages_all() later.
Move this code into the caller(s) under mm->page_table_lock. All other
updates to ->locked_vm hold mmap_sem for writing.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff -puN mm/mmap.c~mm-fix-the-racy-mm-locked_vm-change-in mm/mmap.c
--- a/mm/mmap.c~mm-fix-the-racy-mm-locked_vm-change-in
+++ a/mm/mmap.c
@@ -2138,10 +2138,6 @@ static int acct_stack_growth(struct vm_a
if (security_vm_enough_memory_mm(mm, grow))
return -ENOMEM;
- /* Ok, everything looks good - let it rip */
- if (vma->vm_flags & VM_LOCKED)
- mm->locked_vm += grow;
- vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
return 0;
}
@@ -2202,6 +2198,10 @@ int expand_upwards(struct vm_area_struct
* against concurrent vma expansions.
*/
spin_lock(&vma->vm_mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ vma->vm_mm->locked_vm += grow;
+ vm_stat_account(vma->vm_mm, vma->vm_flags,
+ vma->vm_file, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_end = address;
anon_vma_interval_tree_post_update_vma(vma);
@@ -2273,6 +2273,10 @@ int expand_downwards(struct vm_area_stru
* against concurrent vma expansions.
*/
spin_lock(&vma->vm_mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ vma->vm_mm->locked_vm += grow;
+ vm_stat_account(vma->vm_mm, vma->vm_flags,
+ vma->vm_file, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_start = address;
vma->vm_pgoff -= grow;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
mm-fix-the-racy-mm-locked_vm-change-in.patch
mm-add-the-struct-mm_struct-mm-local-into.patch
signals-kill-block_all_signals-and-unblock_all_signals.patch
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