Re: [syzbot] INFO: task hung in __lru_add_drain_all

From: syzbot
Date: Sun Sep 05 2021 - 02:13:48 EST

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in synchronize_rcu

INFO: task kworker/u4:4:135 blocked for more than 143 seconds.
Not tainted 5.14.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:4 state:D stack:26552 pid: 135 ppid: 2 flags:0x00004000
Workqueue: events_unbound fsnotify_connector_destroy_workfn
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0x940/0x26f0 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
schedule_timeout+0x1db/0x2a0 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x176/0x280 kernel/sched/completion.c:138
__synchronize_srcu+0x1f4/0x290 kernel/rcu/srcutree.c:930
fsnotify_connector_destroy_workfn+0x49/0xa0 fs/notify/mark.c:164
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
process_scheduled_works kernel/workqueue.c:2360 [inline]
worker_thread+0x85c/0x11f0 kernel/workqueue.c:2446
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task kworker/u4:6:852 blocked for more than 144 seconds.
Not tainted 5.14.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6 state:D stack:25784 pid: 852 ppid: 2 flags:0x00004000
Workqueue: events_unbound fsnotify_mark_destroy_workfn
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0x940/0x26f0 kernel/sched/core.c:6287
schedule+0xd3/0x270 kernel/sched/core.c:6366
schedule_timeout+0x1db/0x2a0 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x176/0x280 kernel/sched/completion.c:138
__synchronize_srcu+0x1f4/0x290 kernel/rcu/srcutree.c:930
fsnotify_mark_destroy_workfn+0xfd/0x340 fs/notify/mark.c:860
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
process_scheduled_works kernel/workqueue.c:2360 [inline]
worker_thread+0x85c/0x11f0 kernel/workqueue.c:2446
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 PID: 1634 Comm: khungtaskd Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xc1d/0xf50 kernel/hung_task.c:295
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: kworker/u4:2 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:lock_acquire+0x33/0x510 kernel/locking/lockdep.c:5593
Code: df 41 57 41 89 f7 41 56 49 89 fe 41 55 41 89 d5 41 54 41 89 cc 55 44 89 c5 53 48 81 ec b0 00 00 00 48 8d 5c 24 10 4c 89 0c 24 <48> c7 44 24 10 b3 8a b5 41 48 c1 eb 03 48 c7 44 24 18 ca d8 14 8b
RSP: 0018:ffffc90000e2fba0 EFLAGS: 00000286
RAX: dffffc0000000000 RBX: ffffc90000e2fbb0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8b97f960
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff88d220e1 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: ffffffff8b97f960 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc6d467a718 CR3: 000000002bece000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
rcu_lock_acquire include/linux/rcupdate.h:267 [inline]
rcu_read_lock include/linux/rcupdate.h:687 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:410 [inline]
batadv_nc_worker+0x12d/0xfa0 net/batman-adv/network-coding.c:721
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
----------------
Code disassembly (best guess):
0: df 41 57 filds 0x57(%rcx)
3: 41 89 f7 mov %esi,%r15d
6: 41 56 push %r14
8: 49 89 fe mov %rdi,%r14
b: 41 55 push %r13
d: 41 89 d5 mov %edx,%r13d
10: 41 54 push %r12
12: 41 89 cc mov %ecx,%r12d
15: 55 push %rbp
16: 44 89 c5 mov %r8d,%ebp
19: 53 push %rbx
1a: 48 81 ec b0 00 00 00 sub $0xb0,%rsp
21: 48 8d 5c 24 10 lea 0x10(%rsp),%rbx
26: 4c 89 0c 24 mov %r9,(%rsp)
* 2a: 48 c7 44 24 10 b3 8a movq $0x41b58ab3,0x10(%rsp) <-- trapping instruction
31: b5 41
33: 48 c1 eb 03 shr $0x3,%rbx
37: 48 c7 44 24 18 ca d8 movq $0xffffffff8b14d8ca,0x18(%rsp)
3e: 14 8b


Tested on:

commit: 49624efa Merge tag 'denywrite-for-5.15' of git://githu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16810735300000
kernel config: https://syzkaller.appspot.com/x/.config?x=faed7df0f442c217
dashboard link: https://syzkaller.appspot.com/bug?extid=a9b681dcbc06eb2bca04
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
patch: https://syzkaller.appspot.com/x/patch.diff?x=11d0a286300000