From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4F8DC00523 for ; Wed, 8 Jan 2020 06:04:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B65162073A for ; Wed, 8 Jan 2020 06:04:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726210AbgAHGEK (ORCPT ); Wed, 8 Jan 2020 01:04:10 -0500 Received: from mail-io1-f71.google.com ([209.85.166.71]:51269 "EHLO mail-io1-f71.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725773AbgAHGEK (ORCPT ); Wed, 8 Jan 2020 01:04:10 -0500 Received: by mail-io1-f71.google.com with SMTP id t18so1370100iob.18 for ; Tue, 07 Jan 2020 22:04:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=sXfiajJd0SBFtR8AxsIiru7JfmtGS4gym6AkvwNYLLo=; b=P6W7mo6H5XH/zt6+HeO/7or6Qe9x3ynfbZSyhkTyZ0ZZGHESKmi/12MGnsRB/88mEE EEfwp/YE1e0gss+A1zZoAKObwRcf6+tSJbQp2LFxwJUP+iPlmFalUzMylUtCDY2NXS5m 7ifkndl18Rfan+Y/j4TVZti4WS0nf4VwnisNlBx1ty+RymHQaBt0hFDl4eTObgE+uO3i bQ0CxBCUAtBrEVjtztCtJJsq/wN1X+P56QoOWx2ZApWzp1P7NMlOGVZL6cXBgBHyA8pe J7SqfPSNvJVvG4QISK5BUMICzWbgecoo52rV5bSDeFBS41v6nwY82GJ+4scQNwvmVe08 oiAQ== X-Gm-Message-State: APjAAAXjHLuKob0pZ6oAb9R8hqvdvcbqIjdQF/ofb1rE0ZEPOT0/rA6T EMxIAd5lHvAD79WX2zl7YtmE5jj4oK00fpotIUJhlpB2aqBW X-Google-Smtp-Source: APXvYqz9/uae4T8VmnATWjjkDK5bCKNLbG2w3UBqNzOEHwjOeZu/Y1Ts3C2tBZ05LoR7vcfEa/iAYyos0Az6M5fPNI3+aaQRych9 MIME-Version: 1.0 X-Received: by 2002:a02:a898:: with SMTP id l24mr2733990jam.107.1578463449457; Tue, 07 Jan 2020 22:04:09 -0800 (PST) Date: Tue, 07 Jan 2020 22:04:09 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000322ad2059b9aa992@google.com> Subject: INFO: rcu detected stall in sys_poll (2) From: syzbot To: akpm@linux-foundation.org, christian@brauner.io, keescook@chromium.org, linux-kernel@vger.kernel.org, luto@amacapital.net, mingo@kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, wad@chromium.org Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: ae608821 Merge tag 'trace-v5.5-rc5' of git://git.kernel.or.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=157edeb9e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=db5ff86cbb23b415 dashboard link: https://syzkaller.appspot.com/bug?extid=c3ed57cd8f699826dd95 compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+c3ed57cd8f699826dd95@syzkaller.appspotmail.com rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (1 GPs behind) idle=5da/1/0x4000000000000002 softirq=13907/13908 fqs=38 (t=10501 jiffies g=6889 q=136) rcu: rcu_preempt kthread starved for 10426 jiffies! g6889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 0 CPU: 0 PID: 8477 Comm: udevd Not tainted 5.5.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:free_thread_stack+0x151/0x590 kernel/fork.c:280 Code: 31 f6 e8 02 8d 6f 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 73 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 55 94 6a 00 48 8b 3b be fc ff ff ff e8 28 04 00 RSP: 0018:ffffc90001e57760 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff11013e8ed61 RBX: ffff88809f476b08 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002a59a40 RBP: ffffc90001e57798 R08: 000000000003a728 R09: ffffed10125b3711 R10: ffffed10125b3711 R11: 0000000000000000 R12: ffff88809f476a20 R13: dffffc0000000000 R14: 1ffff11013e8ed44 R15: ffff888092d9b878 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_hrtimeout_range_clock+0x3c7/0x510 kernel/time/hrtimer.c:2130 schedule_hrtimeout_range+0x2a/0x40 kernel/time/hrtimer.c:2175 poll_schedule_timeout+0x11c/0x1c0 fs/select.c:243 do_poll fs/select.c:951 [inline] do_sys_poll+0x83f/0x1250 fs/select.c:1001 __do_sys_poll fs/select.c:1059 [inline] __se_sys_poll+0x1b0/0x360 fs/select.c:1047 __x64_sys_poll+0x7b/0x90 fs/select.c:1047 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fe82049b678 Code: 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 90 90 90 48 83 ec 28 8b 05 82 8f 2b 00 85 c0 75 17 48 63 d2 b8 07 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 48 83 c4 28 c3 89 54 24 08 48 89 74 24 10 RSP: 002b:00007fffd9dcc090 EFLAGS: 00000246 ORIG_RAX: 0000000000000007 RAX: ffffffffffffffda RBX: 20c49ba5e353f7cf RCX: 00007fe82049b678 RDX: 000000000000ee2a RSI: 0000000000000001 RDI: 00007fffd9dcc150 RBP: 0000000000000000 R08: 00007fffd9dcc0a0 R09: 00007fffd9de50b8 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000150dc00 R13: 000000000000214d R14: 00007fffd9dcc124 R15: 0000000001509250 --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.