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 B56F0C2D0C0 for ; Mon, 23 Dec 2019 09:45:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91D9E20709 for ; Mon, 23 Dec 2019 09:45:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726717AbfLWJpJ (ORCPT ); Mon, 23 Dec 2019 04:45:09 -0500 Received: from mail-il1-f200.google.com ([209.85.166.200]:56310 "EHLO mail-il1-f200.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id 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X-Received: by 2002:a5e:d616:: with SMTP id w22mr18472866iom.57.1577094307832; Mon, 23 Dec 2019 01:45:07 -0800 (PST) Date: Mon, 23 Dec 2019 01:45:07 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000feecd9059a5be1b7@google.com> Subject: INFO: rcu detected stall in do_signal (4) From: syzbot To: christian@brauner.io, ebiederm@xmission.com, linux-kernel@vger.kernel.org, oleg@redhat.com, syzkaller-bugs@googlegroups.com 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: 2187f215 Merge tag 'for-5.5-rc2-tag' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10031a8ee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=ab2ae0615387ef78 dashboard link: https://syzkaller.appspot.com/bug?extid=7e600afa7f6059f9a30e compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=163852fee00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=135b43b6e00000 Bisection is inconclusive: the bug happens on the oldest tested release. bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=123dc849e00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=113dc849e00000 console output: https://syzkaller.appspot.com/x/log.txt?x=163dc849e00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+7e600afa7f6059f9a30e@syzkaller.appspotmail.com hrtimer: interrupt took 92494 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=8669, q=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295016466-4295005964), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor765 R running task 28552 9407 9389 0x00000000 Call Trace: sched_show_task kernel/sched/core.c:5954 [inline] sched_show_task.cold+0x2ee/0x35d kernel/sched/core.c:5929 print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline] check_cpu_stall kernel/rcu/tree_stall.h:538 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq.cold+0xaf4/0xc02 kernel/rcu/tree.c:2271 update_process_times+0x2d/0x70 kernel/time/timer.c:1726 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x4f/0x80 kernel/locking/spinlock.c:199 Code: c0 e8 34 93 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 52 f5 ca 01 00 74 20 fb 66 0f 1f 44 00 00 01 00 00 00 e8 e7 7b 88 f9 65 8b 05 d8 de 39 78 85 c0 74 06 41 RSP: 0000:ffffc90001f47ca0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff132669d RBX: 0000000000000000 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff888095ca8b54 RBP: ffffc90001f47ca8 R08: ffff888095ca82c0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a8ef0b80 R13: ffff8880a8ef0cc0 R14: dffffc0000000000 R15: 000000000000000b spin_unlock_irq include/linux/spinlock.h:388 [inline] get_signal+0x1bee/0x24f0 kernel/signal.c:2737 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160 prepare_exit_to_usermode+0x321/0x3a0 arch/x86/entry/common.c:195 ret_from_intr+0x26/0x36 RIP: 0033:0x401505 Code: 00 00 00 be b4 fe 4a 00 e8 48 ee ff ff 48 85 c0 0f 85 d2 fe ff ff e9 4a ff ff ff e8 55 d9 04 00 48 6b 44 24 28 18 8b 7c 24 38 <48> 8b 88 50 00 00 20 48 8b 90 48 00 00 20 48 8b b0 40 00 00 20 e8 RSP: 002b:00007f51c6df1b20 EFLAGS: 00010202 RAX: 0000000002f54358 RBX: 00000000006dcc28 RCX: 0000000000406cc7 RDX: 60b237aef639e3c2 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00000000006dcc20 R08: 00007f51c6df1b20 R09: 00000000006dcc20 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000006dcc2c R13: 00007ffcd25bbb6f R14: 00007f51c6df29c0 R15: 00000000006dcc20 rcu: rcu_preempt kthread starved for 10502 jiffies! g8669 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29272 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0x9b2/0x18d0 kernel/rcu/tree.c:1821 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches