From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757017Ab3KOKSt (ORCPT ); Fri, 15 Nov 2013 05:18:49 -0500 Received: from mail-ee0-f52.google.com ([74.125.83.52]:48311 "EHLO mail-ee0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752460Ab3KOKSj (ORCPT ); Fri, 15 Nov 2013 05:18:39 -0500 From: Peter Wu To: Dave Jones Cc: Al Viro , Linux Kernel Subject: Re: recursive locking (coredump/vfs_write) Date: Fri, 15 Nov 2013 11:18:35 +0100 Message-ID: <1531328.VGTlsG5iNH@al> User-Agent: KMail/4.11.3 (Linux/3.12.0-1-custom; KDE/4.11.3; x86_64; ; ) In-Reply-To: <20131113211147.GA30263@redhat.com> References: <20131113211147.GA30263@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wednesday 13 November 2013 16:11:47 Dave Jones wrote: > Hey Al, > > here's another one.. > > [..] I also saw this warning with a slightly different path. Kernel is v3.12-7033-g42a2d92, the out-of-tree module below is unrelated (bbswitch). This was triggered when trying trying to get a coredump by running /lib/libGL.so after manually changing kernel.core_pattern back to "core" as systemd hijacked this setting. libGL.so[23053]: segfault at 1 ip 0000000000000001 sp 00007fffc8829418 error 14 in mesa-libGL.so.1.2.0[7f7d9fa9c000+5a000] ============================================= [ INFO: possible recursive locking detected ] 3.12.0-1-custom #1 Tainted: G O --------------------------------------------- libGL.so/23053 is trying to acquire lock: (sb_writers#3){.+.+.+}, at: [] vfs_write+0x173/0x1f0 but task is already holding lock: (sb_writers#3){.+.+.+}, at: [] do_coredump+0xdd5/0xf20 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sb_writers#3); lock(sb_writers#3); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by libGL.so/23053: #0: (sb_writers#3){.+.+.+}, at: [] do_coredump+0xdd5/0xf20 stack backtrace: CPU: 2 PID: 23053 Comm: libGL.so Tainted: G O 3.12.0-1-custom #1 Hardware name: CLEVO CO. B7130 /B7130 , BIOS 6.00 08/27/2010 ffffffff8207ac50 ffff8800ae1a1828 ffffffff815be016 ffffffff8207ac50 ffff8800ae1a18f0 ffffffff810af393 000202d200000000 0000000000000246 ffff88023bff4740 0000000000000001 0000000000000000 00000000003aa1d5 Call Trace: [] dump_stack+0x4d/0x66 [] __lock_acquire+0x16c3/0x1a60 [] ? __lock_acquire+0x2bd/0x1a60 [] lock_acquire+0x93/0x120 [] ? vfs_write+0x173/0x1f0 [] __sb_start_write+0xc1/0x190 [] ? vfs_write+0x173/0x1f0 [] ? vfs_write+0x173/0x1f0 [] ? security_file_permission+0x23/0xa0 [] vfs_write+0x173/0x1f0 [] dump_emit+0x87/0xc0 [] elf_core_dump+0xcd8/0x14b0 [] ? elf_core_dump+0x80e/0x14b0 [] ? mark_held_locks+0xb0/0x130 [] do_coredump+0xbda/0xf20 [] ? __sigqueue_free.part.15+0x33/0x40 [] ? trace_hardirqs_off+0xd/0x10 [] get_signal_to_deliver+0x2aa/0x6a0 [] do_signal+0x48/0x960 [] ? kmem_cache_free+0x95/0x1d0 [] ? final_putname+0x22/0x50 [] ? kmem_cache_free+0x16e/0x1d0 [] ? retint_signal+0x11/0x84 [] do_notify_resume+0x65/0x80 [] retint_signal+0x46/0x84