syzbot


INFO: task hung in _rcu_barrier

Status: auto-closed as invalid on 2020/09/08 15:22
Reported-by: syzbot+697f5ad0fe2d523af622@syzkaller.appspotmail.com
First crash: 806d, last: 774d
similar bugs (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: task hung in _rcu_barrier (2) 2 1099d 1111d 0/1 auto-closed as invalid on 2019/10/25 08:36
android-414 INFO: task hung in _rcu_barrier 13 1369d 1388d 0/1 auto-closed as invalid on 2019/03/23 10:41
android-49 INFO: task hung in _rcu_barrier C 1 1327d 1167d 0/3 public: reported C repro on 2019/04/14 08:51
linux-4.19 INFO: task hung in _rcu_barrier 1 186d 186d 0/1 auto-closed as invalid on 2022/04/19 01:50
linux-4.14 INFO: task hung in _rcu_barrier (2) 1 464d 464d 0/1 auto-closed as invalid on 2021/07/15 03:03
upstream INFO: task hung in _rcu_barrier 3 1348d 1390d 0/22 auto-closed as invalid on 2019/04/13 07:47

Sample crash report:
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: task syz-executor.1:10090 blocked for more than 140 seconds.
      Not tainted 4.14.180-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D27648 10090   6385 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x946/0xe40 kernel/time/timer.c:1723
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common kernel/sched/completion.c:123 [inline]
 wait_for_completion+0x241/0x390 kernel/sched/completion.c:144
 _rcu_barrier+0x285/0x400 kernel/rcu/tree.c:3611
 netdev_run_todo+0xed/0x710 net/core/dev.c:7913
 tun_detach drivers/net/tun.c:587 [inline]
 tun_chr_close+0x46/0x60 drivers/net/tun.c:2671
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x416421
RSP: 002b:00007ffdf473f1b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000416421
RDX: 0000000000000000 RSI: 00000000000016af RDI: 0000000000000005
RBP: 0000000000000001 R08: 00000000aab9f6af R09: 00000000aab9f6b3
R10: 00007ffdf473f2a0 R11: 0000000000000293 R12: 000000000078c900
R13: 000000000078c900 R14: ffffffffffffffff R15: 000000000078bf0c

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff81465d33>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by khugepaged/1064:
 #0:  (pcpu_drain_mutex){+.+.}, at: [<ffffffff816f3e3a>] drain_all_pages+0x4a/0x570 mm/page_alloc.c:2493
2 locks held by agetty/6295:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff833b1c62>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff833a58a4>] n_tty_read+0x1e4/0x16f0 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.1/10090:
 #0:  (rcu_preempt_state.barrier_mutex){+.+.}, at: [<ffffffff814bbc36>] _rcu_barrier+0x56/0x400 kernel/rcu/tree.c:3546

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.180-syzkaller #0
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+0x13e/0x194 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9902 Comm: syz-executor.4 Not tainted 4.14.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88805848c340 task.stack: ffff88804c6f0000
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:addr_limit_user_check include/linux/syscalls.h:240 [inline]
RIP: 0010:prepare_exit_to_usermode+0x83/0x210 arch/x86/entry/common.c:189
RSP: 0000:ffff88804c6f7f38 EFLAGS: 00000046
RAX: 00007ffffffff000 RBX: ffff88805848c340 RCX: 0000000000000000
RDX: 1ffff1100b091af3 RSI: 1ffff110098defdc RDI: ffff88805848d798
RBP: ffff88804c6f7f58 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88805848c340
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fe5e8505700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000353989e0 CR3: 000000008f9fd000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 retint_user+0x8/0x18
RIP: 0033:0x405be9
RSP: 002b:00007fe5e8504a70 EFLAGS: 00010202
RAX: 00000000353989d0 RBX: 0000000000508a20 RCX: 0000000000416687
RDX: 5b3766e45f25eb1c RSI: 0000000000000000 RDI: 0000000000000007
RBP: 000000000078c0e0 R08: 00007fe5e8504a70 R09: 000000000078c0e0
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
R13: 0000000000000bf9 R14: 00000000004ce1ea R15: 00007fe5e85056d4
Code: 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 85 01 00 00 48 b8 00 f0 ff ff ff 7f 00 00 49 39 84 24 58 14 00 00 0f 85 e8 1c 00 00 <e8> a8 d9 59 00 65 48 8b 04 25 40 ee 01 00 f0 80 60 03 7f e8 95 

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/05/11 15:21 linux-4.14.y ab9dfda23248 f8f57555 .config log report
ci2-linux-4-14 2020/04/17 10:11 linux-4.14.y c10b57a567e4 18397578 .config log report
ci2-linux-4-14 2020/04/09 13:08 linux-4.14.y 4520f06b03ae a8c6a3f8 .config log report