From: Bjorn Steinbrink Date: Tue, 5 Feb 2008 06:29:28 +0000 (-0800) Subject: Fix dirty page accounting leak with ext3 data=journal X-Git-Tag: v2.6.25-rc1~928 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=a2b345642f530054a92b8d2b5108436225a8093e;p=linux-2.6-omap-h63xx.git 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 Tested-by: Krzysztof Piotr Oledzki Cc: Jan Kara Cc: Nick Piggin Cc: Peter Zijlstra Cc: Thomas Osterried Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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) return; - cancel_dirty_page(page, PAGE_CACHE_SIZE); - if (PagePrivate(page)) do_invalidatepage(page, 0); + cancel_dirty_page(page, PAGE_CACHE_SIZE); + remove_from_page_cache(page); ClearPageUptodate(page); ClearPageMappedToDisk(page);