On Fri, Apr 6, 2018 at 2:52 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > On Fri, 06 Apr 2018 09:08:01 +0200, > syzbot wrote: >> >> Hello, >> >> syzbot hit the following crash on upstream commit >> e02d37bf55a9a36f22427fd6dd733fe104d817b6 (Thu Apr 5 17:42:07 2018 +0000) >> Merge tag 'sound-4.17-rc1' of >> git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound >> syzbot dashboard link: >> https://syzkaller.appspot.com/bug?extid=7e3f31a52646f939c052 >> >> So far this crash happened 43 times on upstream. >> Unfortunately, I don't have any reproducer for this crash yet. >> Raw console output: >> https://syzkaller.appspot.com/x/log.txt?id=5148264345108480 >> Kernel config: >> https://syzkaller.appspot.com/x/.config?id=-4805825610197092128 >> compiler: gcc (GCC) 8.0.1 20180301 (experimental) >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+7e3f31a52646f939c052@xxxxxxxxxxxxxxxxxxxxxxxxx >> 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 >> 1-...!: (124999 ticks this GP) idle=522/1/4611686018427387906 >> softirq=65432/65432 fqs=169 >> (t=125000 jiffies g=35384 c=35383 q=537) >> rcu_sched kthread starved for 124294 jiffies! g35384 c35383 f0x0 >> RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 >> RCU grace-period kthread stack dump: >> rcu_sched R running task 23768 9 2 0x80000000 >> Call Trace: >> context_switch kernel/sched/core.c:2848 [inline] >> __schedule+0x807/0x1e40 kernel/sched/core.c:3490 >> schedule+0xef/0x430 kernel/sched/core.c:3549 >> schedule_timeout+0x138/0x240 kernel/time/timer.c:1801 >> rcu_gp_kthread+0x6b5/0x1940 kernel/rcu/tree.c:2231 >> kthread+0x345/0x410 kernel/kthread.c:238 >> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 >> NMI backtrace for cpu 1 >> CPU: 1 PID: 15299 Comm: syz-executor3 Not tainted 4.16.0+ #2 >> Hardware name: Google Google Compute Engine/Google Compute Engine, >> BIOS Google 01/01/2011 >> Call Trace: >> <IRQ> >> __dump_stack lib/dump_stack.c:17 [inline] >> dump_stack+0x1b9/0x29f lib/dump_stack.c:53 >> nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 >> nmi_trigger_cpumask_backtrace+0x151/0x192 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+0x175/0x1c2 kernel/rcu/tree.c:1376 >> print_cpu_stall kernel/rcu/tree.c:1525 [inline] >> check_cpu_stall.isra.61.cold.80+0x36c/0x59a kernel/rcu/tree.c:1593 >> __rcu_pending kernel/rcu/tree.c:3356 [inline] >> rcu_pending kernel/rcu/tree.c:3401 [inline] >> rcu_check_callbacks+0x21b/0xad0 kernel/rcu/tree.c:2763 >> update_process_times+0x2d/0x70 kernel/time/timer.c:1636 >> tick_sched_handle+0xa0/0x180 kernel/time/tick-sched.c:171 >> tick_sched_timer+0x42/0x130 kernel/time/tick-sched.c:1179 >> __run_hrtimer kernel/time/hrtimer.c:1337 [inline] >> __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1399 >> hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1457 >> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline] >> smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050 >> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862 >> </IRQ> >> RIP: 0010:arch_local_irq_enable arch/x86/include/asm/paravirt.h:793 [inline] >> RIP: 0010:snd_pcm_stream_unlock_irq+0xb7/0xf0 sound/core/pcm_native.c:166 >> RSP: 0018:ffff8801c3f27560 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 >> RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc900038d5000 >> RDX: 0000000000040000 RSI: ffffffff859ca760 RDI: ffffffff88b172b8 >> RBP: ffff8801c3f27568 R08: ffff8801abf86af8 R09: 0000000000000006 >> R10: ffff8801abf86280 R11: 0000000000000000 R12: 0000000000000004 >> R13: 00000000ffffffe0 R14: ffff8801d7d9e1c0 R15: ffff8801ceac6940 >> __snd_pcm_lib_xfer+0x739/0x1d10 sound/core/pcm_lib.c:2246 >> snd_pcm_oss_write3+0xe9/0x220 sound/core/oss/pcm_oss.c:1236 >> io_playback_transfer+0x274/0x310 sound/core/oss/io.c:47 >> snd_pcm_plug_write_transfer+0x36c/0x470 sound/core/oss/pcm_plugin.c:619 >> snd_pcm_oss_write2+0x25c/0x460 sound/core/oss/pcm_oss.c:1365 >> snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1415 [inline] >> snd_pcm_oss_write+0x764/0xa20 sound/core/oss/pcm_oss.c:2774 >> __vfs_write+0x10b/0x880 fs/read_write.c:485 >> vfs_write+0x1f8/0x560 fs/read_write.c:549 >> ksys_write+0xf9/0x250 fs/read_write.c:598 >> SYSC_write fs/read_write.c:610 [inline] >> SyS_write+0x24/0x30 fs/read_write.c:607 >> do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x42/0xb7 >> RIP: 0033:0x4552d9 >> RSP: 002b:00007f1568de6c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >> RAX: ffffffffffffffda RBX: 00007f1568de76d4 RCX: 00000000004552d9 >> RDX: 0000000000000060 RSI: 0000000020000000 RDI: 0000000000000013 >> RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff >> R13: 00000000000006c0 R14: 00000000006fd2a0 R15: 0000000000000000 > > Hmm, a problem that appears like the issue we've already fixed strikes > back. Maybe because of the recent my code change for further > hardening of PCM OSS. > > If there is a reproducer, I'd take a deeper look, but currently I > couldn't see the obvious cause, and all reproducers in the past seem > working. So if you get any reproducer, please let me know. > > There are a couple of pending small fixes that might cure this, and > I'm going to submit & merge before 4.17-rc1, in anyway. Hi Takashi, syzbot will notify when/if a reproducer is available. It happens pretty actively, so if it is cured by any commits, we will see it stop happening here: https://syzkaller.appspot.com/bug?extid=7e3f31a52646f939c052 There is also a bunch of similarly looking rcu stalls (also in sound and started happening all at once): https://syzkaller.appspot.com/bug?id=f087e17667da6944617675babc90277bc5a7b34e https://syzkaller.appspot.com/bug?id=55381513d03b0098c2905ae1a48b4cc7c3b25a22 https://syzkaller.appspot.com/bug?id=f9364472bcbd3cb1738f774dd3711668cb402216 With high probability it is something that was just merged upstream. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
