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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2007-02-28 20:13:49 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-03-01 14:53:39 -0800 |
| commit | 34bbd704051c9d053d69e90569a3a2365f4c7b50 (patch) | |
| tree | f5fb6f3941cd09be0fb92ae80f9759ad64fca709 | |
| parent | 48dba8ab9b93c3b6b57946bd45ae013402b0b054 (diff) | |
| download | linux-34bbd704051c9d053d69e90569a3a2365f4c7b50.tar.bz2 | |
[PATCH] adapt page_lock_anon_vma() to PREEMPT_RCU
page_lock_anon_vma() uses spin_lock() to block RCU. This doesn't work with
PREEMPT_RCU, we have to do rcu_read_lock() explicitely. Otherwise, it is
theoretically possible that slab returns anon_vma's memory to the system
before we do spin_unlock(&anon_vma->lock).
[ Hugh points out that this only matters for PREEMPT_RCU, which isn't merged
yet, and may never be. Regardless, this patch is conceptually the
right thing to do, even if it doesn't matter at this point. - Linus ]
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/rmap.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 669acb22b572..22ed3f71a674 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -183,7 +183,7 @@ void __init anon_vma_init(void) */ static struct anon_vma *page_lock_anon_vma(struct page *page) { - struct anon_vma *anon_vma = NULL; + struct anon_vma *anon_vma; unsigned long anon_mapping; rcu_read_lock(); @@ -195,9 +195,16 @@ static struct anon_vma *page_lock_anon_vma(struct page *page) anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); + return anon_vma; out: rcu_read_unlock(); - return anon_vma; + return NULL; +} + +static void page_unlock_anon_vma(struct anon_vma *anon_vma) +{ + spin_unlock(&anon_vma->lock); + rcu_read_unlock(); } /* @@ -333,7 +340,8 @@ static int page_referenced_anon(struct page *page) if (!mapcount) break; } - spin_unlock(&anon_vma->lock); + + page_unlock_anon_vma(anon_vma); return referenced; } @@ -802,7 +810,8 @@ static int try_to_unmap_anon(struct page *page, int migration) if (ret == SWAP_FAIL || !page_mapped(page)) break; } - spin_unlock(&anon_vma->lock); + + page_unlock_anon_vma(anon_vma); return ret; } |