From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 72BFA6B0012 for ; Mon, 30 May 2011 05:37:51 -0400 (EDT) From: Jan Kara Subject: [PATCH] mm: Fix assertion mapping->nrpages == 0 in end_writeback() Date: Mon, 30 May 2011 11:37:38 +0200 Message-Id: <1306748258-4732-1-git-send-email-jack@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, Al Viro , mszeredi@suse.cz, Jan Kara , Jay , stable@kernel.org 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 cycling the mapping->tree_lock at the end of truncate_inode_pages_range() to synchronize with page reclaim. Analyzed by Jay , lost in LKML, and dug out by Miklos Szeredi . CC: Jay CC: stable@kernel.org Acked-by: Miklos Szeredi Signed-off-by: Jan Kara --- mm/truncate.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) Andrew, would you merge this patch please? Thanks. diff --git a/mm/truncate.c b/mm/truncate.c index a956675..ec3d292 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -291,6 +291,13 @@ void truncate_inode_pages_range(struct address_space *mapping, pagevec_release(&pvec); mem_cgroup_uncharge_end(); } + /* + * Cycle the tree_lock to make sure all __delete_from_page_cache() + * calls run from page reclaim have finished as well (this handles the + * case when page reclaim took the last page from our range). + */ + spin_lock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); } EXPORT_SYMBOL(truncate_inode_pages_range); -- 1.7.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org