Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753754AbdLMRKm (ORCPT ); Wed, 13 Dec 2017 12:10:42 -0500 Received: from mail-oi0-f48.google.com ([209.85.218.48]:37892 "EHLO mail-oi0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753209AbdLMRKj (ORCPT ); Wed, 13 Dec 2017 12:10:39 -0500 X-Google-Smtp-Source: ACJfBotJPv5CUjuO7uuwkB2PsffDoeG7DWgGSXjFQ4BRnie+7VHrEnlZCsu5M68uaQqHmq8ntfEPPw== Subject: Re: Crash in cgroup_procs_show To: Tejun Heo Cc: Zefan Li , linux-kernel@vger.kernel.org, regressions@leemhuis.info References: <39625861-99c0-1c15-08a6-49b9d678c4c2@redhat.com> <20171213152914.GN3919388@devbig577.frc2.facebook.com> From: Laura Abbott Message-ID: <121dc065-89ba-98ab-68ff-e86f1a636b06@redhat.com> Date: Wed, 13 Dec 2017 09:10:36 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171213152914.GN3919388@devbig577.frc2.facebook.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3364 Lines: 69 On 12/13/2017 07:29 AM, Tejun Heo wrote: > Hello, Laura. > > On Tue, Dec 12, 2017 at 04:38:33PM -0800, Laura Abbott wrote: >> Hi, >> >> Fedora got a bug report on 4.14.4 of a crash on >> reboot https://bugzilla.redhat.com/show_bug.cgi?id=1525279 >> >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000254 >> IP: __task_pid_nr_ns+0xc7/0xf0 > > Any chance you can map this back to the source line with addr2line? > > Thanks. > annotated with decode_stacktrace.sh IP: __task_pid_nr_ns (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/pid.c:506 /usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/pid.c:535) cgroup_procs_show (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/cgroup/cgroup.c:4240) cgroup_seqfile_show (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/kernel/cgroup/cgroup.c:3413) kernfs_seq_show (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/kernfs/file.c:169) seq_read (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/seq_file.c:269) kernfs_fop_read (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/kernfs/file.c:252) __vfs_read (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/read_write.c:416) ? security_file_permission (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/include/linux/fsnotify.h:56 /usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/security/security.c:867) vfs_read (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/read_write.c:448) SyS_read (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/read_write.c:574 /usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/fs/read_write.c:566) entry_SYSCALL_64_fastpath (/usr/src/debug/kernel-4.14.fc26/linux-4.14.4-200.fc26.x86_64/arch/x86/entry/entry_64.S:206) All code ======== 0: 04 74 add $0x74,%al 2: 0e (bad) 3: 89 f6 mov %esi,%esi 5: 48 8d 04 76 lea (%rsi,%rsi,2),%rax 9: 48 8d 04 c5 f0 05 00 lea 0x5f0(,%rax,8),%rax 10: 00 11: 48 8b bf b8 05 00 00 mov 0x5b8(%rdi),%rdi 18: 48 01 c7 add %rax,%rdi 1b: 31 c0 xor %eax,%eax 1d: 48 8b 0f mov (%rdi),%rcx 20: 48 85 c9 test %rcx,%rcx 23: 74 18 je 0x3d 25: 8b b2 30 08 00 00 mov 0x830(%rdx),%esi 2b:* 3b 71 04 cmp 0x4(%rcx),%esi <-- trapping instruction 2e: 77 0d ja 0x3d 30: 48 c1 e6 05 shl $0x5,%rsi 34: 48 01 f1 add %rsi,%rcx 37: 48 3b 51 38 cmp 0x38(%rcx),%rdx 3b: 74 09 je 0x46 3d: 5d pop %rbp 3e: c3 retq 3f: 8b .byte 0x8b Code starting with the faulting instruction =========================================== 0: 3b 71 04 cmp 0x4(%rcx),%esi 3: 77 0d ja 0x12 5: 48 c1 e6 05 shl $0x5,%rsi 9: 48 01 f1 add %rsi,%rcx c: 48 3b 51 38 cmp 0x38(%rcx),%rdx 10: 74 09 je 0x1b 12: 5d pop %rbp 13: c3 retq 14: 8b .byte 0x8b