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authorJan Kara <jack@suse.cz>2011-06-27 16:18:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-27 18:00:13 -0700
commit08142579b6ca35883c1ed066a2681de6f6917062 (patch)
tree00735ed37753533f3b645714770b4fb036b5f7e0 /kernel/taskstats.c
parent9b679320a5fbf46454011e5c62e0b8991b0956d1 (diff)
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mm: fix assertion mapping->nrpages == 0 in end_writeback()
Under heavy memory and filesystem load, users observe the assertion mapping->nrpages == 0 in end_writeback() trigger. This can be caused by page reclaim reclaiming the last page from a mapping in the following race: CPU0 CPU1 ... shrink_page_list() __remove_mapping() __delete_from_page_cache() radix_tree_delete() evict_inode() truncate_inode_pages() truncate_inode_pages_range() pagevec_lookup() - finds nothing end_writeback() mapping->nrpages != 0 -> BUG page->mapping = NULL mapping->nrpages-- Fix the problem by doing a reliable check of mapping->nrpages under mapping->tree_lock in end_writeback(). Analyzed by Jay <jinshan.xiong@whamcloud.com>, lost in LKML, and dug out by Miklos Szeredi <mszeredi@suse.de>. Cc: Jay <jinshan.xiong@whamcloud.com> Cc: Miklos Szeredi <mszeredi@suse.de> Signed-off-by: Jan Kara <jack@suse.cz> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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