INFO: rcu detected stall in comm_write

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b850307b Linux 4.14.184
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15d05fad100000
kernel config: https://syzkaller.appspot.com/x/.config?x=ddc0f08dd6b981c5
dashboard link: https://syzkaller.appspot.com/bug?extid=b6a3d0cf652d0a607c4f
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+b6a3d0...@syzkaller.appspotmail.com

hub 9-0:1.0: 8 ports detected
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: rcu_preempt self-detected stall on CPU
1-...: (1 GPs behind) idle=a46/140000000000001/0 softirq=14507/14510 fqs=5235
(t=10500 jiffies g=2505 c=2504 q=2550)
NMI backtrace for cpu 1
CPU: 1 PID: 8794 Comm: syz-executor.5 Not tainted 4.14.184-syzkaller #0
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+0x1b2/0x283 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:158 [inline]
rcu_dump_cpu_stacks+0x16d/0x1b8 kernel/rcu/tree.c:1396
print_cpu_stall kernel/rcu/tree.c:1542 [inline]
check_cpu_stall kernel/rcu/tree.c:1610 [inline]
__rcu_pending kernel/rcu/tree.c:3390 [inline]
rcu_pending kernel/rcu/tree.c:3452 [inline]
rcu_check_callbacks.cold+0x490/0xdaa kernel/rcu/tree.c:2792
update_process_times+0x29/0x60 kernel/time/timer.c:1590
tick_sched_handle.isra.0+0x73/0x150 kernel/time/tick-sched.c:165
tick_sched_timer+0x41/0x120 kernel/time/tick-sched.c:1223
__run_hrtimer kernel/time/hrtimer.c:1223 [inline]
__hrtimer_run_queues+0x24b/0xb90 kernel/time/hrtimer.c:1287
hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
smp_apic_timer_interrupt+0x117/0x5f0 arch/x86/kernel/apic/apic.c:1100
apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:793
</IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x28/0x50 kernel/kcov.c:93
RSP: 0018:ffff8880a801f658 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: 0000000000040000 RBX: ffff888096d9a8c0 RCX: ffffc90007ec0000
RDX: 0000000000040000 RSI: ffffffff81684212 RDI: ffffffff87bdbd98
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000020012
R10: ffff88808587ab30 R11: ffff88808587a280 R12: ffff888094a5a640
R13: ffff88809ecab670 R14: 0000000000000000 R15: ffff8880a801f750
pmu_filter_match kernel/events/core.c:1816 [inline]
event_filter_match kernel/events/core.c:1828 [inline]
perf_iterate_ctx+0x442/0x5f0 kernel/events/core.c:6363
perf_iterate_sb+0x632/0x8c0 kernel/events/core.c:6424
perf_event_comm_event kernel/events/core.c:6744 [inline]
perf_event_comm+0x190/0x1e0 kernel/events/core.c:6771
set_task_comm include/linux/sched.h:1560 [inline]
comm_write+0x1b1/0x1f0 fs/proc/base.c:1561
__vfs_write+0xe4/0x630 fs/read_write.c:480
__kernel_write+0xf5/0x330 fs/read_write.c:501
write_pipe_buf+0x143/0x1b0 fs/splice.c:797
splice_from_pipe_feed fs/splice.c:502 [inline]
__splice_from_pipe+0x332/0x740 fs/splice.c:626
splice_from_pipe+0xc6/0x120 fs/splice.c:661
default_file_splice_write+0x37/0x80 fs/splice.c:809
do_splice_from fs/splice.c:851 [inline]
direct_splice_actor+0x115/0x160 fs/splice.c:1018
splice_direct_to_actor+0x27e/0x730 fs/splice.c:973
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x469/0xaf0 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1502 [inline]
SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45cb19
RSP: 002b:00007f29af75bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004fd640 RCX: 000000000045cb19
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 00008000fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000901 R14: 00000000004cbddf R15: 00007f29af75c6d4
INFO: rcu_sched detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=a46/140000000000000/0 softirq=14508/14510 fqs=5235
(detected by 0, t=10546 jiffies, g=1059, c=1058, q=53)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8794 Comm: syz-executor.5 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808587a280 task.stack: ffff8880a8018000
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:60
RSP: 0018:ffff8880a801f658 EFLAGS: 00000206
RAX: ffff888094a5a650 RBX: ffff888096d9a8c0 RCX: ffffc90007ec0000
RDX: 0000000000040000 RSI: ffffffff81684212 RDI: ffff888094a5a650
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000020012
R10: ffff88808587ab30 R11: ffff88808587a280 R12: ffff888094a5a640
R13: ffff88809ecab670 R14: 0000000000000000 R15: ffff8880a801f750
FS: 00007f29af75c700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe183b7c80 CR3: 00000000937a5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__pmu_filter_match kernel/events/core.c:1799 [inline]
pmu_filter_match kernel/events/core.c:1817 [inline]
event_filter_match kernel/events/core.c:1828 [inline]
perf_iterate_ctx+0x3e4/0x5f0 kernel/events/core.c:6363
perf_iterate_sb+0x632/0x8c0 kernel/events/core.c:6424
perf_event_comm_event kernel/events/core.c:6744 [inline]
perf_event_comm+0x190/0x1e0 kernel/events/core.c:6771
set_task_comm include/linux/sched.h:1560 [inline]
comm_write+0x1b1/0x1f0 fs/proc/base.c:1561
__vfs_write+0xe4/0x630 fs/read_write.c:480
__kernel_write+0xf5/0x330 fs/read_write.c:501
write_pipe_buf+0x143/0x1b0 fs/splice.c:797
splice_from_pipe_feed fs/splice.c:502 [inline]
__splice_from_pipe+0x332/0x740 fs/splice.c:626
splice_from_pipe+0xc6/0x120 fs/splice.c:661
default_file_splice_write+0x37/0x80 fs/splice.c:809
do_splice_from fs/splice.c:851 [inline]
direct_splice_actor+0x115/0x160 fs/splice.c:1018
splice_direct_to_actor+0x27e/0x730 fs/splice.c:973
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x469/0xaf0 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1502 [inline]
SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45cb19
RSP: 002b:00007f29af75bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004fd640 RCX: 000000000045cb19
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 00008000fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000901 R14: 00000000004cbddf R15: 00007f29af75c6d4
Code: 00 48 c7 c7 c0 94 8d 86 4c 89 3d 3c f2 dd 08 41 bd f4 ff ff ff e8 9c de ee ff 48 c7 05 26 f2 dd 08 00 00 00 00 e9 be ed ff ff 90 <65> 48 8b 04 25 40 ee 01 00 48 85 c0 74 1a 65 8b 15 db 47 a7 7e
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-... } 10725 jiffies s: 2557 root: 0x2/.
blocking rcu_node structures:
Task dump for CPU 1:
syz-executor.5 R running task 26432 8794 6354 0x8000000e
Call Trace:


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.