path: root/mm/truncate.c
diff options
authorBjorn Steinbrink <B.Steinbrink@gmx.de>2008-02-04 22:29:28 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:19 -0800
commita2b345642f530054a92b8d2b5108436225a8093e (patch)
tree9be466168baf0fb0c57504e9fe87aec07f09445a /mm/truncate.c
parentae1276b9349a2fd9c3afb4651e25a77ac03299d9 (diff)
Fix dirty page accounting leak with ext3 data=journal
In 46d2277c796f9f4937bfa668c40b2e3f43e93dd0 ("Clean up and make try_to_free_buffers() not race with dirty pages"), try_to_free_buffers was changed to bail out if the page was dirty. That in turn caused truncate_complete_page to leak massive amounts of memory, because the dirty bit was only cleared after the call to try_to_free_buffers. So the call to cancel_dirty_page was moved up to have the dirty bit cleared early in 3e67c0987d7567ad666641164a153dca9a43b11d ("truncate: clear page dirtiness before running try_to_free_buffers()"). The problem with that fix is, that the page can be redirtied after cancel_dirty_page was called, eg. like this: truncate_complete_page() cancel_dirty_page() // PG_dirty cleared, decr. dirty pages do_invalidatepage() ext3_invalidatepage() journal_invalidatepage() journal_unmap_buffer() __dispose_buffer() __journal_unfile_buffer() __journal_temp_unlink_buffer() mark_buffer_dirty(); // PG_dirty set, incr. dirty pages And then we end up with dirty pages being wrongly accounted. As a result, in ecdfc9787fe527491baefc22dce8b2dbd5b2908d ("Resurrect 'try_to_free_buffers()' VM hackery") the changes to try_to_free_buffers were reverted, so the original reason for the massive memory leak is gone, and we can also revert the move of the call to cancel_dirty_page from truncate_complete_page and get the accounting right again. I'm not sure if it matters, but opposed to the final check in __remove_from_page_cache, this one also cares about the task io accounting, so maybe we want to use this instead, although it's not quite the clean fix either. Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de> Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl> Cc: Jan Kara <jack@ucw.cz> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Osterried <osterried@jesse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/truncate.c')
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 3855492f1c3..9838c050e2d 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -98,11 +98,11 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
- cancel_dirty_page(page, PAGE_CACHE_SIZE);
if (PagePrivate(page))
do_invalidatepage(page, 0);
+ cancel_dirty_page(page, PAGE_CACHE_SIZE);