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author | Ingo Molnar <mingo@elte.hu> | 2010-09-15 10:27:31 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2010-09-15 10:27:31 +0200 |
commit | 3aabae7d9dfaed60effe93662f02c19bafc18537 (patch) | |
tree | af94cdd69add07601d9f3f5988dfc1dc255e3886 /mm/rmap.c | |
parent | tracing: Remove leftover FTRACE_ENABLE/DISABLE_MCOUNT enums (diff) | |
parent | tracing: Fix reading of set_ftrace_filter across lists (diff) | |
download | linux-dev-3aabae7d9dfaed60effe93662f02c19bafc18537.tar.xz linux-dev-3aabae7d9dfaed60effe93662f02c19bafc18537.zip |
Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
Diffstat (limited to 'mm/rmap.c')
-rw-r--r-- | mm/rmap.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 87b9e8ad4509..f6f0d2dda2ea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -316,7 +316,7 @@ void __init anon_vma_init(void) */ struct anon_vma *page_lock_anon_vma(struct page *page) { - struct anon_vma *anon_vma; + struct anon_vma *anon_vma, *root_anon_vma; unsigned long anon_mapping; rcu_read_lock(); @@ -327,8 +327,21 @@ struct anon_vma *page_lock_anon_vma(struct page *page) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); - anon_vma_lock(anon_vma); - return anon_vma; + root_anon_vma = ACCESS_ONCE(anon_vma->root); + spin_lock(&root_anon_vma->lock); + + /* + * If this page is still mapped, then its anon_vma cannot have been + * freed. But if it has been unmapped, we have no security against + * the anon_vma structure being freed and reused (for another anon_vma: + * SLAB_DESTROY_BY_RCU guarantees that - so the spin_lock above cannot + * corrupt): with anon_vma_prepare() or anon_vma_fork() redirecting + * anon_vma->root before page_unlock_anon_vma() is called to unlock. + */ + if (page_mapped(page)) + return anon_vma; + + spin_unlock(&root_anon_vma->lock); out: rcu_read_unlock(); return NULL; |