syzbot


INFO: rcu detected stall in __process_echoes

Status: fixed on 2018/07/09 18:05
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+108696293d7a21ab688f@syzkaller.appspotmail.com
Fix commit: ebec3f8f5271 n_tty: Access echo_* variables carefully.
First crash: 2219d, last: 2122d
Duplicate bugs (5)
duplicates (5):
Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
INFO: task hung in perf_trace_event_unreg trace 1 2213d 2213d 0/26 closed as dup on 2018/04/02 16:04
INFO: task hung in isig serial 1 2167d 2167d 0/26 closed as dup on 2018/05/18 10:23
BUG: soft lockup in __process_echoes serial C 1 2135d 2134d 0/26 closed as dup on 2018/06/20 11:32
INFO: rcu detected stall in commit_echoes serial C 237 2122d 2218d 0/26 closed as dup on 2018/03/28 07:12
INFO: rcu detected stall in n_tty_receive_buf_common serial C 32 2130d 2214d 0/26 closed as dup on 2018/03/31 15:56
Discussions (7)
Title Replies (including bot) Last reply
[PATCH 3.16 000/366] 3.16.61-rc1 review 375 (376) 2019/01/02 17:44
[PATCH 4.4 00/47] 4.4.140-stable review 56 (56) 2018/07/28 05:56
[PATCH 4.9 00/52] 4.9.112-stable review 59 (60) 2018/07/11 20:12
[PATCH 4.14 00/61] 4.14.54-stable review 57 (58) 2018/07/09 13:28
[PATCH 4.17 00/46] 4.17.5-stable review 34 (35) 2018/07/07 21:40
[PATCH 1/2] n_tty: Fix stall at n_tty_receive_char_special(). 4 (4) 2018/06/04 11:57
INFO: rcu detected stall in __process_echoes 1 (2) 2018/04/22 02:04

Sample crash report:
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
sshd (4488) used greatest stack depth: 16920 bytes left
random: sshd: uninitialized urandom read (32 bytes read)
INFO: rcu_sched self-detected stall on CPU
	0-....: (124999 ticks this GP) idle=862/1/4611686018427387906 softirq=10647/10647 fqs=31088 
	 (t=125000 jiffies g=4911 c=4910 q=1)
NMI backtrace for cpu 0
CPU: 0 PID: 49 Comm: kworker/u4:2 Not tainted 4.17.0-rc2+ #21
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 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+0x9f/0x180 kernel/time/tick-sched.c:173
 tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1283
 __run_hrtimer kernel/time/hrtimer.c:1386 [inline]
 __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1448
 hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1506
 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:863
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x15/0x20 kernel/kcov.c:174
RSP: 0018:ffff8801d95b7258 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 0000000218ab6391 RCX: ffffffff8397b039
RDX: 0000000000000000 RSI: 0000000000000082 RDI: 0000000000000001
RBP: ffff8801d95b7258 R08: ffff8801d958c4c0 R09: 0000000000000006
R10: ffff8801d958c4c0 R11: 0000000000000000 R12: ffffc90001e54000
R13: 0000000000001203 R14: 0000000000000000 R15: 00000000000000ff
 __process_echoes+0x249/0x8d0 drivers/tty/n_tty.c:733
 commit_echoes+0x163/0x1d0 drivers/tty/n_tty.c:764
 n_tty_receive_char_fast drivers/tty/n_tty.c:1416 [inline]
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1576 [inline]
 __receive_buf drivers/tty/n_tty.c:1611 [inline]
 n_tty_receive_buf_common+0x2048/0x2c50 drivers/tty/n_tty.c:1709
 n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1744
 tty_ldisc_receive_buf+0xb0/0x190 drivers/tty/tty_buffer.c:456
 tty_port_default_receive_buf+0x110/0x170 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:475 [inline]
 flush_to_ldisc+0x3e9/0x560 drivers/tty/tty_buffer.c:524
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Crashes (326):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/04/28 12:48 upstream 46dc111dfe47 d5a5d045 .config console log report syz C ci-upstream-kasan-gce-root
2018/03/27 20:27 upstream 3eb2ce825ea1 bf5e585c .config console log report syz C ci-upstream-kasan-gce-root
2018/07/01 19:36 upstream 883c9ab9eb59 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/07/01 17:59 upstream 883c9ab9eb59 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/07/01 14:58 upstream 883c9ab9eb59 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/07/01 06:16 upstream 0fbc4aeabc91 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/07/01 03:58 upstream 0fbc4aeabc91 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 19:40 upstream 1904148a361a dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 18:36 upstream 1904148a361a dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 13:59 upstream 1904148a361a dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 12:53 upstream 1904148a361a dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 06:39 upstream 1904148a361a dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/30 00:05 upstream 2cd3ae212973 dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/29 08:49 upstream 90368a37fbbe dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/29 04:46 upstream 90368a37fbbe dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/28 19:53 upstream f57494321cbf dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/28 16:45 upstream f57494321cbf dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/28 10:38 upstream f57494321cbf dba0b50e .config console log report ci-upstream-kasan-gce-root
2018/06/28 01:08 upstream debd52a05061 43e60f7e .config console log report ci-upstream-kasan-gce-root
2018/06/27 23:41 upstream debd52a05061 43e60f7e .config console log report ci-upstream-kasan-gce-root
2018/06/27 17:57 upstream debd52a05061 43e60f7e .config console log report ci-upstream-kasan-gce-root
2018/06/27 12:00 upstream 813835028e9a 43e60f7e .config console log report ci-upstream-kasan-gce-root
2018/06/27 04:03 upstream 813835028e9a b0294c53 .config console log report ci-upstream-kasan-gce-root
2018/06/26 10:47 upstream 6f0d349d922b 2064fc5c .config console log report ci-upstream-kasan-gce-root
2018/06/25 19:10 upstream 6f0d349d922b 2064fc5c .config console log report ci-upstream-kasan-gce-root
2018/06/24 21:30 upstream 7daf201d7fe8 2064fc5c .config console log report ci-upstream-kasan-gce-root
2018/06/22 08:54 upstream 27db64f65f1b 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/22 05:28 upstream 27db64f65f1b 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/21 18:49 upstream 1abd8a8f39cd 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/21 17:11 upstream 1abd8a8f39cd 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/21 13:38 upstream 1abd8a8f39cd 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/21 10:57 upstream 1abd8a8f39cd 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/20 17:17 upstream 81e97f01371f 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/20 14:36 upstream 81e97f01371f 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/20 03:08 upstream ba4dbdedd3ed 095ef806 .config console log report ci-upstream-kasan-gce-root
2018/06/19 19:14 upstream ba4dbdedd3ed 732e4256 .config console log report ci-upstream-kasan-gce-root
2018/06/19 17:27 upstream ba4dbdedd3ed 732e4256 .config console log report ci-upstream-kasan-gce-root
2018/06/19 15:59 upstream ba4dbdedd3ed 732e4256 .config console log report ci-upstream-kasan-gce-root
2018/06/19 14:01 upstream ba4dbdedd3ed 732e4256 .config console log report ci-upstream-kasan-gce-root
2018/06/19 11:08 upstream ba4dbdedd3ed 732e4256 .config console log report ci-upstream-kasan-gce-root
2018/06/19 08:37 upstream ba4dbdedd3ed 45c54f75 .config console log report ci-upstream-kasan-gce-root
2018/06/18 04:08 upstream ce397d215ccd 27c5f59f .config console log report ci-upstream-kasan-gce-root
2018/06/18 02:13 upstream ce397d215ccd 27c5f59f .config console log report ci-upstream-kasan-gce-root
2018/06/17 23:59 upstream ce397d215ccd 27c5f59f .config console log report ci-upstream-kasan-gce-root
2018/06/17 21:55 upstream ce397d215ccd 27c5f59f .config console log report ci-upstream-kasan-gce-root
2018/03/26 18:38 upstream 3eb2ce825ea1 0ca7878b .config console log report ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.