Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753941AbcJKQZc (ORCPT ); Tue, 11 Oct 2016 12:25:32 -0400 Received: from arcturus.aphlor.org ([188.246.204.175]:49394 "EHLO arcturus.aphlor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753329AbcJKQZa (ORCPT ); Tue, 11 Oct 2016 12:25:30 -0400 Date: Tue, 11 Oct 2016 12:25:07 -0400 From: Dave Jones To: Chris Mason Cc: Al Viro , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, Linux Kernel Subject: Re: btrfs bio linked list corruption. Message-ID: <20161011162507.5xaldh47ow7mba5m@codemonkey.org.uk> Mail-Followup-To: Dave Jones , Chris Mason , Al Viro , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, Linux Kernel References: <20161011144507.okg6baqvodn2m2lh@codemonkey.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20160916 (1.7.0) X-Spam-Flag: skipped (authorised relay user) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3337 Lines: 58 On Tue, Oct 11, 2016 at 11:54:09AM -0400, Chris Mason wrote: > > > On 10/11/2016 10:45 AM, Dave Jones wrote: > > This is from Linus' current tree, with Al's iovec fixups on top. > > > > ------------[ cut here ]------------ > > WARNING: CPU: 1 PID: 3673 at lib/list_debug.c:33 __list_add+0x89/0xb0 > > list_add corruption. prev->next should be next (ffffe8ffff806648), but was ffffc9000067fcd8. (prev=ffff880503878b80). > > CPU: 1 PID: 3673 Comm: trinity-c0 Not tainted 4.8.0-think+ #13 > > ffffc90000d87458 ffffffff8d32007c ffffc90000d874a8 0000000000000000 > > ffffc90000d87498 ffffffff8d07a6c1 0000002100000246 ffff88050388e880 > > ffff880503878b80 ffffe8ffff806648 ffffe8ffffc06600 ffff880502808008 > > Call Trace: > > [] dump_stack+0x4f/0x73 > > [] __warn+0xc1/0xe0 > > [] warn_slowpath_fmt+0x5a/0x80 > > [] __list_add+0x89/0xb0 > > [] blk_sq_make_request+0x2f8/0x350 > > /* > * A task plug currently exists. Since this is completely lockless, > * utilize that to temporarily store requests until the task is > * either done or scheduled away. > */ > plug = current->plug; > if (plug) { > blk_mq_bio_to_request(rq, bio); > if (!request_count) > trace_block_plug(q); > > blk_mq_put_ctx(data.ctx); > > if (request_count >= BLK_MAX_REQUEST_COUNT) { > blk_flush_plug_list(plug, false); > trace_block_plug(q); > } > > list_add_tail(&rq->queuelist, &plug->mq_list); > ^^^^^^^^^^^^^^^^^^^^^^ > > Dave, is this where we're crashing? This seems strange. According to objdump -S .. ffffffff8130a1b7: 48 8b 70 50 mov 0x50(%rax),%rsi list_add_tail(&rq->queuelist, &ctx->rq_list); ffffffff8130a1bb: 48 8d 50 48 lea 0x48(%rax),%rdx ffffffff8130a1bf: 48 89 45 a8 mov %rax,-0x58(%rbp) ffffffff8130a1c3: e8 38 44 03 00 callq ffffffff8133e600 <__list_add> blk_mq_hctx_mark_pending(hctx, ctx); ffffffff8130a1c8: 48 8b 45 a8 mov -0x58(%rbp),%rax ffffffff8130a1cc: 4c 89 ff mov %r15,%rdi That looks like the list_add_tail from __blk_mq_insert_req_list Dave