From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755507AbZCCPC2 (ORCPT ); Tue, 3 Mar 2009 10:02:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752858AbZCCPCU (ORCPT ); Tue, 3 Mar 2009 10:02:20 -0500 Received: from cam-admin0.cambridge.arm.com ([193.131.176.58]:42600 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752641AbZCCPCT (ORCPT ); Tue, 3 Mar 2009 10:02:19 -0500 Subject: Re: Regression - locking (all from 2.6.28) From: Catalin Marinas To: Andrew Morton Cc: jan sonnek , linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, Peter Zijlstra In-Reply-To: <1236076864.8547.20.camel@pc1117.cambridge.arm.com> References: <49AC334A.9030800@gmail.com> <20090302121127.e46dc4be.akpm@linux-foundation.org> <1236076864.8547.20.camel@pc1117.cambridge.arm.com> Content-Type: text/plain Organization: ARM Ltd Date: Tue, 03 Mar 2009 15:01:20 +0000 Message-Id: <1236092480.8547.67.camel@pc1117.cambridge.arm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 03 Mar 2009 15:01:32.0485 (UTC) FILETIME=[F07C2F50:01C99C10] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2009-03-03 at 10:41 +0000, Catalin Marinas wrote: > On Mon, 2009-03-02 at 12:11 -0800, Andrew Morton wrote: > > > Mar 1 00:06:51 localhost kernel: [ 74.008165] unreferenced object 0xf6c4daf0 (size 52): > > > Mar 1 00:06:51 localhost kernel: [ 74.008170] comm "swapper", pid 1, jiffies 4294893427 > > > Mar 1 00:06:51 localhost kernel: [ 74.008175] backtrace: > > > Mar 1 00:06:51 localhost kernel: [ 74.008179] [] kmemleak_alloc+0x17e/0x28e > > > Mar 1 00:06:51 localhost kernel: [ 74.008185] [] kmem_cache_alloc+0xdc/0xe7 > > > Mar 1 00:06:51 localhost kernel: [ 74.008190] [] alloc_buffer_head+0x16/0x71 > > > Mar 1 00:06:51 localhost kernel: [ 74.008196] [] alloc_page_buffers+0x23/0xad > > > Mar 1 00:06:51 localhost kernel: [ 74.008200] [] __getblk+0x192/0x26b > > > Mar 1 00:06:51 localhost kernel: [ 74.008205] [] jread+0x105/0x1de > > > Mar 1 00:06:51 localhost kernel: [ 74.008209] [] do_one_pass+0x5e/0x38c > > > Mar 1 00:06:51 localhost kernel: [ 74.008213] [] journal_recover+0x41/0x9d > > > Mar 1 00:06:51 localhost kernel: [ 74.008218] [] journal_load+0x47/0x7b > > > Mar 1 00:06:51 localhost kernel: [ 74.008221] [] ext3_fill_super+0xe9d/0x144c > > > Mar 1 00:06:51 localhost kernel: [ 74.008225] [] get_sb_bdev+0xfa/0x140 > > > Mar 1 00:06:51 localhost kernel: [ 74.008231] [] ext3_get_sb+0x18/0x1a > > > Mar 1 00:06:51 localhost kernel: [ 74.008235] [] vfs_kern_mount+0x41/0x7c > > > Mar 1 00:06:51 localhost kernel: [ 74.008241] [] do_kern_mount+0x37/0xbe > > > Mar 1 00:06:51 localhost kernel: [ 74.008247] [] do_mount+0x5f7/0x630 > > > Mar 1 00:06:51 localhost kernel: [ 74.008253] [] sys_mount+0x6f/0xac > > > > I suspect kmemleak has gone nuts here. > > It seems that the buffer_head structure allocated above is stored in > page->private. However, the page structures are no longer scanned in > newer versions of kmemleak. That's the hunk that was removed after > comments about the contiguity of a node's memory: > > + /* mem_map scanning */ > + for_each_online_node(i) { > + struct page *page, *end; > + > + page = NODE_MEM_MAP(i); > + end = page + NODE_DATA(i)->node_spanned_pages; > + > + scan_block(page, end, NULL); > + } > > The alternative is to inform kmemleak about the page structures returned > from __alloc_pages_internal() but there would be problems with recursive > calls into kmemleak when it allocates its own data structures. > > I'll look at re-adding the hunk above, maybe with some extra checks like > pfn_valid(). Looking again at this, the node_mem_map is always contiguous and the code above only scans the node_mem_map, not the memory represented by the node (which may not be contiguous). So I think it is a valid code sequence. If the above gets too deep into the nodes structure, an alternative would be: diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 09b6fd7..0f17e62 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3552,6 +3552,11 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) map = alloc_remap(pgdat->node_id, size); if (!map) map = alloc_bootmem_node(pgdat, size); + /* + * Inform kmemleak to scan the node_mem_map arrays as the page + * structure may contain pointers to other objects. + */ + kmemleak_alloc(map, size, 1, GFP_ATOMIC); pgdat->node_mem_map = map + (pgdat->node_start_pfn - start); } #ifndef CONFIG_NEED_MULTIPLE_NODES -- Catalin