Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942575AbcJZMsW (ORCPT ); Wed, 26 Oct 2016 08:48:22 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56041 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942291AbcJZMfJ (ORCPT ); Wed, 26 Oct 2016 08:35:09 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Weiner , Andrew Morton , Miklos Szeredi , Linus Torvalds , Michal Hocko Subject: [PATCH 4.4 092/112] mm: filemap: fix mapping->nrpages double accounting in fuse Date: Wed, 26 Oct 2016 14:23:15 +0200 Message-Id: <20161026122308.654531852@linuxfoundation.org> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20161026122304.797016625@linuxfoundation.org> References: <20161026122304.797016625@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1810 Lines: 46 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johannes Weiner commit 3ddf40e8c31964b744ff10abb48c8e36a83ec6e7 upstream. Commit 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") switched replace_page_cache() from raw radix tree operations to page_cache_tree_insert() but didn't take into account that the latter function, unlike the raw radix tree op, handles mapping->nrpages. As a result, that counter is bumped for each page replacement rather than balanced out even. The mapping->nrpages counter is used to skip needless radix tree walks when invalidating, truncating, syncing inodes without pages, as well as statistics for userspace. Since the error is positive, we'll do more page cache tree walks than necessary; we won't miss a necessary one. And we'll report more buffer pages to userspace than there are. The error is limited to fuse inodes. Fixes: 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") Signed-off-by: Johannes Weiner Cc: Andrew Morton Cc: Miklos Szeredi Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Michal Hocko Signed-off-by: Greg Kroah-Hartman --- mm/filemap.c | 1 - 1 file changed, 1 deletion(-) --- a/mm/filemap.c +++ b/mm/filemap.c @@ -590,7 +590,6 @@ int replace_page_cache_page(struct page __delete_from_page_cache(old, NULL, memcg); error = page_cache_tree_insert(mapping, new, NULL); BUG_ON(error); - mapping->nrpages++; /* * hugetlb pages do not participate in page cache accounting.