diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2015-11-05 18:48:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-05 19:34:48 -0800 |
| commit | 87e8827b37c0c391d9915d0dc6a06c9b5f9cac65 (patch) | |
| tree | 9164f29c1f758212177668b95eb3363bda501240 /mm/mmap.c | |
| parent | 9fd745d450e7e2b0d2f1b386b886e7d568b64404 (diff) | |
| download | lwn-87e8827b37c0c391d9915d0dc6a06c9b5f9cac65.tar.gz lwn-87e8827b37c0c391d9915d0dc6a06c9b5f9cac65.zip | |
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@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 3ec19b601be0..d1ac22485998 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2138,10 +2138,6 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns 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 *vma, unsigned long address) * 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_struct *vma, * 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; |