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| author | Nick Piggin <npiggin@suse.de> | 2006-02-07 12:58:52 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-02-07 16:12:33 -0800 |
| commit | 8519fb30e438f8088b71a94a7d5a660a814d3872 (patch) | |
| tree | 8d29a7b1fa33e5f65e649d363cfa10e83c4fab97 /mm | |
| parent | 99f6d61bda82d09b2d94414d413d39f66a0b7da2 (diff) | |
| download | linux-8519fb30e438f8088b71a94a7d5a660a814d3872.tar.bz2 | |
[PATCH] mm: compound release fix
Compound pages on SMP systems can now often be freed from pagetables via
the release_pages path. This uses put_page_testzero which does not handle
compound pages at all. Releasing constituent pages from process mappings
decrements their count to a large negative number and leaks the reference
at the head page - net result is a memory leak.
The problem was hidden because the debug check in put_page_testzero itself
actually did take compound pages into consideration.
Fix the bug and the debug check.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/swap.c | 32 |
1 files changed, 22 insertions, 10 deletions
diff --git a/mm/swap.c b/mm/swap.c index bc2442a7b0ee..76247424dea1 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -34,19 +34,22 @@ /* How many pages do we try to swap or page in/out together? */ int page_cluster; -void put_page(struct page *page) +static void put_compound_page(struct page *page) { - if (unlikely(PageCompound(page))) { - page = (struct page *)page_private(page); - if (put_page_testzero(page)) { - void (*dtor)(struct page *page); + page = (struct page *)page_private(page); + if (put_page_testzero(page)) { + void (*dtor)(struct page *page); - dtor = (void (*)(struct page *))page[1].mapping; - (*dtor)(page); - } - return; + dtor = (void (*)(struct page *))page[1].mapping; + (*dtor)(page); } - if (put_page_testzero(page)) +} + +void put_page(struct page *page) +{ + if (unlikely(PageCompound(page))) + put_compound_page(page); + else if (put_page_testzero(page)) __page_cache_release(page); } EXPORT_SYMBOL(put_page); @@ -244,6 +247,15 @@ void release_pages(struct page **pages, int nr, int cold) struct page *page = pages[i]; struct zone *pagezone; + if (unlikely(PageCompound(page))) { + if (zone) { + spin_unlock_irq(&zone->lru_lock); + zone = NULL; + } + put_compound_page(page); + continue; + } + if (!put_page_testzero(page)) continue; |