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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 /fs/inode.c
parent9b679320a5fbf46454011e5c62e0b8991b0956d1 (diff)
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>
Diffstat (limited to 'fs/inode.c')
-rw-r--r--fs/inode.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 0f7e88a7803f..43566d17d1b8 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -423,7 +423,14 @@ EXPORT_SYMBOL(remove_inode_hash);
void end_writeback(struct inode *inode)
{
might_sleep();
+ /*
+ * We have to cycle tree_lock here because reclaim can be still in the
+ * process of removing the last page (in __delete_from_page_cache())
+ * and we must not free mapping under it.
+ */
+ spin_lock_irq(&inode->i_data.tree_lock);
BUG_ON(inode->i_data.nrpages);
+ spin_unlock_irq(&inode->i_data.tree_lock);
BUG_ON(!list_empty(&inode->i_data.private_list));
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);

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