INFO: task hung in acct

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syzbot

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Feb 3, 2021, 1:45:17 AM2/3/21

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Hello,

syzbot found the following issue on:

HEAD commit: 811218ec Linux 4.19.172
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17228a40d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1cb1d27398c8808
dashboard link: https://syzkaller.appspot.com/bug?extid=142da932e85a993bd6c1

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+142da9...@syzkaller.appspotmail.com

RDX: 00000000200003c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0ec01771d0 R08: 0000000020000440 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff2e2523ef R14: 00007f0ec0177300 R15: 0000000000022000
INFO: task syz-executor.4:701 blocked for more than 140 seconds.
Not tainted 4.19.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D29952 701 8108 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1002 [inline]
__mutex_lock+0x647/0x1260 kernel/locking/mutex.c:1072
__do_sys_acct kernel/acct.c:285 [inline]
__se_sys_acct+0x8c/0x930 kernel/acct.c:273
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465b09
Code: 44 24 30 48 8b 08 48 89 0c 24 48 89 44 24 08 c6 44 24 10 01 e8 28 78 fa ff 48 8b 44 24 18 48 89 44 24 38 48 8b 6c 24 20 48 83 <c4> 28 c3 e8 0f 4d 00 00 eb ad cc cc cc cc cc cc cc cc cc cc cc cc
RSP: 002b:00007f2b56442188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0
RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe44a488af R14: 00007f2b56442300 R15: 0000000000022000
INFO: task syz-executor.4:750 blocked for more than 140 seconds.
Not tainted 4.19.172-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D29192 750 8108 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3619
__mutex_lock_common kernel/locking/mutex.c:1002 [inline]
__mutex_lock+0x647/0x1260 kernel/locking/mutex.c:1072
__do_sys_acct kernel/acct.c:285 [inline]
__se_sys_acct+0x8c/0x930 kernel/acct.c:273
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465b09
Code: 44 24 30 48 8b 08 48 89 0c 24 48 89 44 24 08 c6 44 24 10 01 e8 28 78 fa ff 48 8b 44 24 18 48 89 44 24 38 48 8b 6c 24 20 48 83 <c4> 28 c3 e8 0f 4d 00 00 eb ad cc cc cc cc cc cc cc cc cc cc cc cc
RSP: 002b:00007f2b56442188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0
RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe44a488af R14: 00007f2b56442300 R15: 0000000000022000

Showing all locks held in the system:
3 locks held by kworker/u4:1/23:
#0: 00000000c412ff3a (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9701 [inline]
#0: 00000000c412ff3a (&rq->lock){-.-.}, at: pick_next_task_fair+0x556/0x1570 kernel/sched/fair.c:6840
#1: 000000007641ee21 (rcu_read_lock){....}, at: cpu_of kernel/sched/sched.h:921 [inline]
#1: 000000007641ee21 (rcu_read_lock){....}, at: __update_idle_core+0x39/0x3e0 kernel/sched/fair.c:6057
#2: 00000000d0cdef6d (&base->lock){-.-.}, at: lock_timer_base+0x55/0x1b0 kernel/time/timer.c:950
1 lock held by khungtaskd/1562:
#0: 000000007641ee21 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/7809:
#0: 00000000a1e058d8 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
1 lock held by syz-executor.3/30119:
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __do_sys_acct kernel/acct.c:285 [inline]
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __se_sys_acct+0x8c/0x930 kernel/acct.c:273
1 lock held by syz-executor.4/701:
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __do_sys_acct kernel/acct.c:285 [inline]
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __se_sys_acct+0x8c/0x930 kernel/acct.c:273
1 lock held by syz-executor.4/750:
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __do_sys_acct kernel/acct.c:285 [inline]
#0: 00000000c4c3cf6f (acct_on_mutex){+.+.}, at: __se_sys_acct+0x8c/0x930 kernel/acct.c:273

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

NMI backtrace for cpu 0
CPU: 0 PID: 1562 Comm: khungtaskd Not tainted 4.19.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x991/0xe60 kernel/hung_task.c:287
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4684 Comm: systemd-journal Not tainted 4.19.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0033:0x7fb463229bb0
Code: 89 e2 89 ee 48 89 df e8 fe f3 fc ff 85 c0 0f 88 37 fe ff ff 48 8b 74 24 08 e9 5c fe ff ff 66 90 66 2e 0f 1f 84 00 00 00 00 00 <41> 54 55 53 48 83 ec 20 64 48 8b 04 25 28 00 00 00 48 89 44 24 18
RSP: 002b:00007ffda1b0e868 EFLAGS: 00000246
RAX: 0000000000000009 RBX: 0000563d3fb54030 RCX: fffffffffffffe00
RDX: fffffffffffffffe RSI: 0000000000080042 RDI: 0000563d3fb54030
RBP: 000000000000000d R08: 000000000000c0ff R09: 00000000ffffffff
R10: 0000000000000069 R11: 0000000000000000 R12: 00000000ffffffff
R13: 00000000fffffffe R14: 00007ffda1b0eb60 R15: 0000563d3fb54030
FS: 00007fb4635f28c0 GS: 0000000000000000

---
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syzbot

unread,

Feb 3, 2021, 4:41:14 AM2/3/21

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: 811218ec Linux 4.19.172
git tree: linux-4.19.y

console output: https://syzkaller.appspot.com/x/log.txt?x=17c0eea0d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=c1cb1d27398c8808
dashboard link: https://syzkaller.appspot.com/bug?extid=142da932e85a993bd6c1

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13bb628cd00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11577f64d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+142da9...@syzkaller.appspotmail.com

autofs4:pid:8155:autofs_fill_super: called with bogus options
autofs4:pid:8157:autofs_fill_super: called with bogus options
autofs4:pid:8159:autofs_fill_super: called with bogus options
autofs4:pid:8162:autofs_fill_super: called with bogus options
INFO: task syz-executor571:8154 blocked for more than 140 seconds.