From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522511799; cv=none; d=google.com; s=arc-20160816; b=IU1JwWiVvYfy2ye4XSD0j5Vj6y3Ut+5ADCgvYq3CFlaESrsASlyjtw3aO2YJqMXJYE 3xISvJRaZ3uG9iM0c5P3Y7V7unWfC77iTfUabbabfSRAke02J5+0lKyY2kM5WPA57aZU Oq6zfsUu5IWDPmngiV9M0RcvuZTVcL9kzoCHdhN0XAJ8YABVAOA8PQX9PNUSlruOjQLZ P9JxyVAaYCPEn1I0eZftXjR/Dl8cKrsEzKsl7z2R85Ey5z50fwYwIoYkJ2rgRi6NPz2g fgEvbhdeHtHIHlTOKHxL2/ZcCAJ6g43c4x6F6W+s69Cu+SaZ/6GQq10dnX+9ZiuL7sMC 6o1A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:dkim-signature:arc-authentication-results; bh=Ob3Q0loLMoSYKg2G+DFkoDOoINucgfpku7snETrEoHM=; b=v1XvugmAkasDrZqFgCJj1b3Vg8JYsY+INFQUsCnD52nMthNllkY9qnESaiuJxe0L8s HzN7JcUp/vafoemRPDU9A2sOOr2YpIrkSv3EP2EPF3aVlO2yeG2UzKizeKV2NZ4D0WCc D7M2cwVu8vA6UQU6nOEa4aIAxJy/CVPY9+afDbMlu+z/K85aWH607xI3/HcdL4pJz2kh IfMuv8vQBSxqKS+iXcF65UTn3dwUxhoUMvjN9jj0b5qmUb7i1BaHiJ9RKmv0aFPDrmQi +f7ADkt3ZHaKcEq2zEfLIqlTPyTQFyMFKg2y6Khmc2lxGZnflfANIWMpoJUUAiHrBuYZ 8M1w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=AFUdbhXV; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=AFUdbhXV; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com X-Google-Smtp-Source: AIpwx48stTRb58g3qluCozJlKmt4oed8sVzxHQ5rHWQqguxXgrUK2VvNqXLX715g+6ywVxw54UHpx5rNilNMdbpt3sk= MIME-Version: 1.0 In-Reply-To: <94eb2c05b2d829b3db0568b76106@google.com> References: <94eb2c05b2d829b3db0568b76106@google.com> From: Dmitry Vyukov Date: Sat, 31 Mar 2018 17:56:18 +0200 Message-ID: Subject: Re: INFO: rcu detected stall in n_tty_receive_buf_common To: syzbot Cc: Greg Kroah-Hartman , Jiri Slaby , LKML , syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596469230959732817?= X-GMAIL-MSGID: =?utf-8?q?1596469333405250551?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Sat, Mar 31, 2018 at 5:55 PM, syzbot wrote: > Hello, > > syzbot hit the following crash on upstream commit > 0b412605ef5f5c64b31f19e2910b1d5eba9929c3 (Thu Mar 29 01:07:23 2018 +0000) > Merge tag 'drm-fixes-for-v4.16-rc8' of > git://people.freedesktop.org/~airlied/linux > syzbot dashboard link: > https://syzkaller.appspot.com/bug?extid=b7d0f37ffd431e2d698c > > So far this crash happened 2 times on upstream. > C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5308434815647744 > syzkaller reproducer: > https://syzkaller.appspot.com/x/repro.syz?id=5176078016446464 > Raw console output: > https://syzkaller.appspot.com/x/log.txt?id=5940022372990976 > Kernel config: > https://syzkaller.appspot.com/x/.config?id=-8440362230543204781 > compiler: gcc (GCC) 7.1.1 20170620 Looks like: #syz dup: INFO: rcu detected stall in __process_echoes > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+b7d0f37ffd431e2d698c@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > INFO: rcu_sched self-detected stall on CPU > 0-....: (124999 ticks this GP) idle=6ea/1/4611686018427387906 > softirq=9748/9748 fqs=31240 > (t=125000 jiffies g=4823 c=4822 q=10) > NMI backtrace for cpu 0 > CPU: 0 PID: 4469 Comm: syzkaller058368 Not tainted 4.16.0-rc7+ #5 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x24d lib/dump_stack.c:53 > nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 > nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62 > arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 > trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline] > rcu_dump_cpu_stacks+0x186/0x1de kernel/rcu/tree.c:1375 > print_cpu_stall kernel/rcu/tree.c:1524 [inline] > check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1592 > __rcu_pending kernel/rcu/tree.c:3361 [inline] > rcu_pending kernel/rcu/tree.c:3423 [inline] > rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763 > update_process_times+0x30/0x60 kernel/time/timer.c:1636 > tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162 > tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194 > __run_hrtimer kernel/time/hrtimer.c:1349 [inline] > __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411 > hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] > smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857 > > RIP: 0010:echo_buf drivers/tty/n_tty.c:144 [inline] > RIP: 0010:__process_echoes+0x5d9/0x770 drivers/tty/n_tty.c:732 > RSP: 0018:ffff8801af12f7f0 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff12 > RAX: 0000000000000594 RBX: ffffc90001946000 RCX: ffffffff82f38469 > RDX: 0000000000000000 RSI: 1ffff1003543c565 RDI: ffffc900019477f4 > RBP: ffff8801af12f858 R08: 1ffff10035e25ea4 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 00000005e6b39594 > R13: dffffc0000000000 R14: 00000005e6b39594 R15: 0000000000003803 > flush_echoes drivers/tty/n_tty.c:799 [inline] > __receive_buf drivers/tty/n_tty.c:1615 [inline] > n_tty_receive_buf_common+0x1380/0x2520 drivers/tty/n_tty.c:1709 > n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1738 > tiocsti drivers/tty/tty_io.c:2171 [inline] > tty_ioctl+0x9c5/0x1610 drivers/tty/tty_io.c:2557 > vfs_ioctl fs/ioctl.c:46 [inline] > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > SYSC_ioctl fs/ioctl.c:701 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > RIP: 0033:0x446979 > RSP: 002b:00007fb18094bd18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00000000006e29fc RCX: 0000000000446979 > RDX: 00000000200000c0 RSI: 0000000000005412 RDI: 0000000000000004 > RBP: 00000000006e29f8 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 6d74702f7665642f > R13: 00007ffc95813d0f R14: 00007fb18094c9c0 R15: 0000000000000001 > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title > If you want to test a patch for this bug, please reply with: > #syz test: git://repo/address.git branch > and provide the patch inline or as an attachment. > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug > report. > Note: all commands must start from beginning of the line in the email body. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/94eb2c05b2d829b3db0568b76106%40google.com. > For more options, visit https://groups.google.com/d/optout.