From: Hugh Dickins Date: Mon, 8 Oct 2012 23:33:14 +0000 (-0700) Subject: mm: fix invalidate_complete_page2() lock ordering X-Git-Tag: v3.2.32~34 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fa7866bad2e715a2a39fae474fe4fd2704ff8370;p=pandora-kernel.git mm: fix invalidate_complete_page2() lock ordering commit ec4d9f626d5908b6052c2973f37992f1db52e967 upstream. In fuzzing with trinity, lockdep protested "possible irq lock inversion dependency detected" when isolate_lru_page() reenabled interrupts while still holding the supposedly irq-safe tree_lock: invalidate_inode_pages2 invalidate_complete_page2 spin_lock_irq(&mapping->tree_lock) clear_page_mlock isolate_lru_page spin_unlock_irq(&zone->lru_lock) isolate_lru_page() is correct to enable interrupts unconditionally: invalidate_complete_page2() is incorrect to call clear_page_mlock() while holding tree_lock, which is supposed to nest inside lru_lock. Both truncate_complete_page() and invalidate_complete_page() call clear_page_mlock() before taking tree_lock to remove page from radix_tree. I guess invalidate_complete_page2() preferred to test PageDirty (again) under tree_lock before committing to the munlock; but since the page has already been unmapped, its state is already somewhat inconsistent, and no worse if clear_page_mlock() moved up. Reported-by: Sasha Levin Deciphered-by: Andrew Morton Signed-off-by: Hugh Dickins Acked-by: Mel Gorman Cc: Rik van Riel Cc: Johannes Weiner Cc: Michel Lespinasse Cc: Ying Han Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed