Since syzbot found a C reproducer, I reproduced locally with below change applied.
----------------------------------------
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 32b4794..aca1cca 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -115,13 +115,6 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
sysctl_hung_task_warnings--;
pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
t->comm, t->pid, timeout);
- pr_err(" %s %s %.*s\n",
- print_tainted(), init_utsname()->release,
- (int)strcspn(init_utsname()->version, " "),
- init_utsname()->version);
- pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
- " disables this message.\n");
- sched_show_task(t);
hung_task_show_lock = true;
}
@@ -190,8 +183,20 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
}
unlock:
rcu_read_unlock();
- if (hung_task_show_lock)
- debug_show_all_locks();
+ if (hung_task_show_lock) {
+ extern void lockdep_print_held_locks(struct task_struct *p);
+
+ rcu_read_lock();
+ for_each_process_thread(g, t) {
+ if (!t->lockdep_depth)
+ continue;
+ sched_show_task(t);
+ lockdep_print_held_locks(t);
+ touch_nmi_watchdog();
+ touch_all_softlockup_watchdogs();
+ }
+ rcu_read_unlock();
+ }
if (hung_task_call_panic) {
trigger_all_cpu_backtrace();
panic("hung_task: blocked tasks");
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa4d31..e3de52d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -561,7 +561,7 @@ static void print_lock(struct held_lock *hlock)
printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
}
-static void lockdep_print_held_locks(struct task_struct *p)
+void lockdep_print_held_locks(struct task_struct *p)
{
int i, depth = READ_ONCE(p->lockdep_depth);
@@ -575,7 +575,7 @@ static void lockdep_print_held_locks(struct task_struct *p)
* and it's not the current task.
*/
if (p->state == TASK_RUNNING && p != current)
- return;
+ printk("RUNNING TASK\n");
for (i = 0; i < depth; i++) {
printk(" #%d: ", i);
print_lock(p->held_locks + i);
----------------------------------------
It turned out that, although the reason of stalling v9fs_mount() is currently
unknown, the reason of many processes stuck at iterate_supers() is that
they are unable to take s->s_umount object due to down_write_nested() below.
/*
* sget() can have s_umount recursion.
*
* When it cannot find a suitable sb, it allocates a new
* one (this one), and tries again to find a suitable old
* one.
*
* In case that succeeds, it will acquire the s_umount
* lock of the old one. Since these are clearly distrinct
* locks, and this object isn't exposed yet, there's no
* risk of deadlocks.
*
* Annotate this by putting this lock in a different
* subclass.
*/
down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
(The hashed address 00000000d803423d is printed among processes below.)
[ 224.224404] INFO: task a.out:5454 blocked for more than 10 seconds.
[ 224.230981] INFO: task a.out:5476 blocked for more than 10 seconds.
[ 224.237530] INFO: task a.out:5491 blocked for more than 10 seconds.
[ 224.242368] INFO: task a.out:5514 blocked for more than 10 seconds.
[ 224.246407] INFO: task a.out:5529 blocked for more than 10 seconds.
[ 224.250429] INFO: task a.out:5681 blocked for more than 10 seconds.
[ 224.254420] INFO: task a.out:5697 blocked for more than 10 seconds.
[ 224.258822] INFO: task a.out:5711 blocked for more than 10 seconds.
[ 224.262873] INFO: task a.out:5723 blocked for more than 10 seconds.
[ 224.266883] INFO: task a.out:5740 blocked for more than 10 seconds.
[ 224.270740] INFO: task a.out:5757 blocked for more than 10 seconds.
[ 224.272797] INFO: task a.out:5769 blocked for more than 10 seconds.
[ 224.274895] INFO: task a.out:5789 blocked for more than 10 seconds.
[ 224.276914] INFO: task a.out:5799 blocked for more than 10 seconds.
[ 224.278909] INFO: task a.out:5823 blocked for more than 10 seconds.
[ 224.280760] INFO: task a.out:5833 blocked for more than 10 seconds.
[ 224.282612] INFO: task a.out:5456 blocked for more than 10 seconds.
[ 224.284464] INFO: task a.out:5474 blocked for more than 10 seconds.
[ 224.286389] INFO: task a.out:5492 blocked for more than 10 seconds.
[ 224.288445] INFO: task a.out:5526 blocked for more than 10 seconds.
[ 224.290524] INFO: task a.out:5570 blocked for more than 10 seconds.
[ 224.292544] INFO: task a.out:5679 blocked for more than 10 seconds.
[ 224.294551] INFO: task a.out:5693 blocked for more than 10 seconds.
[ 224.296468] INFO: task a.out:5707 blocked for more than 10 seconds.
[ 224.298317] INFO: task a.out:5720 blocked for more than 10 seconds.
[ 224.300167] INFO: task a.out:5745 blocked for more than 10 seconds.
[ 224.302098] INFO: task a.out:5759 blocked for more than 10 seconds.
[ 224.304110] INFO: task a.out:5770 blocked for more than 10 seconds.
[ 224.306111] INFO: task a.out:5786 blocked for more than 10 seconds.
[ 224.308129] INFO: task a.out:5798 blocked for more than 10 seconds.
[ 224.310068] INFO: task a.out:5813 blocked for more than 10 seconds.
[ 224.312073] INFO: task a.out:5825 blocked for more than 10 seconds.
[ 224.313958] INFO: task a.out:5458 blocked for more than 10 seconds.
[ 224.315811] INFO: task a.out:5477 blocked for more than 10 seconds.
[ 224.317721] INFO: task a.out:5485 blocked for more than 10 seconds.
[ 224.319709] INFO: task a.out:5521 blocked for more than 10 seconds.
[ 224.321709] INFO: task a.out:5530 blocked for more than 10 seconds.
[ 224.323633] INFO: task a.out:5575 blocked for more than 10 seconds.
[ 224.325630] INFO: task a.out:5686 blocked for more than 10 seconds.
[ 224.327633] INFO: task a.out:5698 blocked for more than 10 seconds.
[ 224.329602] INFO: task a.out:5719 blocked for more than 10 seconds.
[ 224.331501] INFO: task a.out:5734 blocked for more than 10 seconds.
[ 224.333448] INFO: task a.out:5748 blocked for more than 10 seconds.
[ 224.335411] INFO: task a.out:5763 blocked for more than 10 seconds.
[ 224.337343] INFO: task a.out:5775 blocked for more than 10 seconds.
[ 224.339231] INFO: task a.out:5788 blocked for more than 10 seconds.
[ 224.341156] INFO: task a.out:5800 blocked for more than 10 seconds.
[ 224.343165] INFO: task a.out:5821 blocked for more than 10 seconds.
[ 224.345157] INFO: task a.out:5461 blocked for more than 10 seconds.
[ 224.347063] INFO: task a.out:5475 blocked for more than 10 seconds.
[ 224.348970] INFO: task a.out:5486 blocked for more than 10 seconds.
[ 224.351030] INFO: task a.out:5567 blocked for more than 10 seconds.
[ 224.353060] INFO: task a.out:5577 blocked for more than 10 seconds.
[ 224.354909] INFO: task a.out:5672 blocked for more than 10 seconds.
[ 224.356761] INFO: task a.out:5690 blocked for more than 10 seconds.
[ 224.358740] INFO: task a.out:5712 blocked for more than 10 seconds.
[ 224.360722] INFO: task a.out:5722 blocked for more than 10 seconds.
[ 224.362725] INFO: task a.out:5742 blocked for more than 10 seconds.
[ 224.364623] INFO: task a.out:5754 blocked for more than 10 seconds.
[ 224.366649] INFO: task a.out:5768 blocked for more than 10 seconds.
[ 224.368651] INFO: task a.out:5782 blocked for more than 10 seconds.
[ 224.370523] INFO: task a.out:5796 blocked for more than 10 seconds.
[ 224.372377] INFO: task a.out:5811 blocked for more than 10 seconds.
[ 224.374224] INFO: task a.out:5824 blocked for more than 10 seconds.
[ 224.376253] INFO: task a.out:5481 blocked for more than 10 seconds.
[ 224.378262] INFO: task a.out:5494 blocked for more than 10 seconds.
[ 224.380189] INFO: task a.out:5528 blocked for more than 10 seconds.
[ 224.382210] INFO: task a.out:5576 blocked for more than 10 seconds.
[ 224.384217] INFO: task a.out:5662 blocked for more than 10 seconds.
[ 224.386101] INFO: task a.out:5675 blocked for more than 10 seconds.
[ 224.387969] INFO: task a.out:5692 blocked for more than 10 seconds.
[ 224.389825] INFO: task a.out:5708 blocked for more than 10 seconds.
[ 224.391758] INFO: task a.out:5721 blocked for more than 10 seconds.
[ 224.393657] INFO: task a.out:5736 blocked for more than 10 seconds.
[ 224.395577] INFO: task a.out:5750 blocked for more than 10 seconds.
[ 224.397571] INFO: task a.out:5767 blocked for more than 10 seconds.
[ 224.399579] INFO: task a.out:5783 blocked for more than 10 seconds.
[ 224.401539] INFO: task a.out:5795 blocked for more than 10 seconds.
[ 224.403410] INFO: task a.out:5810 blocked for more than 10 seconds.
[ 224.405301] INFO: task a.out:5465 blocked for more than 10 seconds.
[ 224.407194] INFO: task a.out:5483 blocked for more than 10 seconds.
[ 224.409169] INFO: task a.out:5493 blocked for more than 10 seconds.
[ 224.411220] INFO: task a.out:5512 blocked for more than 10 seconds.
[ 224.413257] INFO: task a.out:5571 blocked for more than 10 seconds.
[ 224.415156] INFO: task a.out:5678 blocked for more than 10 seconds.
[ 224.417071] INFO: task a.out:5689 blocked for more than 10 seconds.
[ 224.418921] INFO: task a.out:5710 blocked for more than 10 seconds.
[ 224.420791] INFO: task a.out:5728 blocked for more than 10 seconds.
[ 224.422642] INFO: task a.out:5741 blocked for more than 10 seconds.
[ 224.424491] INFO: task a.out:5753 blocked for more than 10 seconds.
[ 224.426527] INFO: task a.out:5766 blocked for more than 10 seconds.
[ 224.428583] INFO: task a.out:5777 blocked for more than 10 seconds.
[ 224.430508] INFO: task a.out:5792 blocked for more than 10 seconds.
[ 224.432408] INFO: task a.out:5804 blocked for more than 10 seconds.
[ 224.434273] INFO: task a.out:5820 blocked for more than 10 seconds.
[ 224.436125] INFO: task a.out:5467 blocked for more than 10 seconds.
[ 224.437998] INFO: task a.out:5482 blocked for more than 10 seconds.
[ 224.439868] INFO: task a.out:5506 blocked for more than 10 seconds.
[ 224.441763] INFO: task a.out:5513 blocked for more than 10 seconds.
[ 224.443824] INFO: task a.out:5520 blocked for more than 10 seconds.
[ 224.445849] INFO: task a.out:5673 blocked for more than 10 seconds.
[ 224.447810] INFO: task a.out:5691 blocked for more than 10 seconds.
[ 224.449697] INFO: task a.out:5709 blocked for more than 10 seconds.
[ 224.451550] INFO: task a.out:5724 blocked for more than 10 seconds.
[ 224.453425] INFO: task a.out:5739 blocked for more than 10 seconds.
[ 224.455320] INFO: task a.out:5756 blocked for more than 10 seconds.
[ 224.457223] INFO: task a.out:5772 blocked for more than 10 seconds.
[ 224.459271] INFO: task a.out:5787 blocked for more than 10 seconds.
[ 224.461337] INFO: task a.out:5797 blocked for more than 10 seconds.
[ 224.463336] INFO: task a.out:5818 blocked for more than 10 seconds.
[ 224.465229] INFO: task a.out:5831 blocked for more than 10 seconds.
[ 224.467137] INFO: task a.out:5469 blocked for more than 10 seconds.
[ 224.468994] INFO: task a.out:5473 blocked for more than 10 seconds.
[ 224.470930] INFO: task a.out:5484 blocked for more than 10 seconds.
[ 224.472824] INFO: task a.out:5525 blocked for more than 10 seconds.
[ 224.475015] INFO: task a.out:5661 blocked for more than 10 seconds.
[ 224.477571] INFO: task a.out:5671 blocked for more than 10 seconds.
[ 224.479594] INFO: task a.out:5685 blocked for more than 10 seconds.
[ 224.481574] INFO: task a.out:5699 blocked for more than 10 seconds.
[ 224.483441] INFO: task a.out:5704 blocked for more than 10 seconds.
[ 224.485314] INFO: task a.out:5731 blocked for more than 10 seconds.
[ 224.487163] INFO: task a.out:5749 blocked for more than 10 seconds.
[ 224.489028] INFO: task a.out:5765 blocked for more than 10 seconds.
[ 224.490958] INFO: task a.out:5776 blocked for more than 10 seconds.
[ 224.493029] INFO: task a.out:5790 blocked for more than 10 seconds.
[ 224.495054] INFO: task a.out:5801 blocked for more than 10 seconds.
[ 224.497054] INFO: task a.out:5822 blocked for more than 10 seconds.
[ 224.498927] khungtaskd R running task 29656 953 2 0x80000000
[ 224.501027] Call Trace:
[ 224.501796] sched_show_task+0x33a/0x420
[ 224.503205] watchdog+0x7c7/0xba0
[ 224.504277] kthread+0x2e5/0x3e0
[ 224.505373] ? reset_hung_task_detector+0x30/0x30
[ 224.506836] ? kthread_delayed_work_timer_fn+0x250/0x250
[ 224.508467] ret_from_fork+0x3a/0x50
[ 224.509645] 1 lock held by khungtaskd/953:
[ 224.510933] #0: 00000000a7346670 (rcu_read_lock){....}, at: watchdog+0x673/0xba0
[ 224.513358] a.out D27464 5454 1 0x00000004
[ 224.515294] Call Trace:
[ 224.516192] __schedule+0xb55/0x1dd0
[ 224.517399] ? pci_mmcfg_check_reserved+0x120/0x120
[ 224.518997] ? mark_held_locks+0xc8/0x120
[ 224.520392] ? _raw_spin_unlock_irq+0x27/0x70
[ 224.522016] schedule+0x8f/0x1b0
[ 224.523319] rwsem_down_read_failed+0x24c/0x3a0
[ 224.524907] ? rwsem_down_write_failed+0xce0/0xce0
[ 224.526626] ? block_ioctl+0xd7/0x130
[ 224.527932] ? __ia32_sys_tee+0x200/0x200
[ 224.529362] call_rwsem_down_read_failed+0x18/0x30
[ 224.530966] ? call_rwsem_down_read_failed+0x18/0x30
[ 224.532587] down_read+0x4e/0xb0
[ 224.533669] ? iterate_supers+0x113/0x210
[ 224.534939] iterate_supers+0x113/0x210
[ 224.536181] ksys_sync+0xa5/0x170
[ 224.537307] ? sync_filesystem+0x200/0x200
[ 224.538701] ? kasan_check_write+0x14/0x20
[ 224.540061] ? fput+0x18/0x130
[ 224.541107] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe
[ 224.542818] ? do_syscall_64+0x21/0x4e0
[ 224.544182] __ia32_sys_sync+0x9/0x10
[ 224.545437] do_syscall_64+0xd6/0x4e0
[ 224.546675] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 224.548256] RIP: 0033:0x7f774b2694d9
[ 224.549409] Code: Bad RIP value.
[ 224.550481] RSP: 002b:00007f774b966f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
[ 224.552780] RAX: ffffffffffffffda RBX: 0000000000602124 RCX: 00007f774b2694d9
[ 224.554964] RDX: 00007f774b2694d9 RSI: 0000000000000000 RDI: 0000000000000000
[ 224.557068] RBP: 0000000000602120 R08: 00007f774b966f70 R09: 00007f774b966f70
[ 224.559216] R10: 00007f774b966f70 R11: 0000000000000246 R12: 0000000000000000
[ 224.561546] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 224.563801] 1 lock held by a.out/5454:
[ 224.564980] #0: 00000000d803423d (&type->s_umount_key#54){.+.+}, at: iterate_supers+0x113/0x210
[ 224.567645] a.out D27464 5476 1 0x00000004
[ 224.569476] Call Trace:
[ 224.570350] __schedule+0xb55/0x1dd0
[ 224.571556] ? pci_mmcfg_check_reserved+0x120/0x120
[ 224.573065] ? mark_held_locks+0xc8/0x120
[ 224.574334] ? _raw_spin_unlock_irq+0x27/0x70
[ 224.575721] schedule+0x8f/0x1b0
[ 224.576859] rwsem_down_read_failed+0x24c/0x3a0
[ 224.578280] ? rwsem_down_write_failed+0xce0/0xce0
[ 224.579772] ? lock_downgrade+0x840/0x840
[ 224.581060] ? __ia32_sys_tee+0x200/0x200
[ 224.582311] call_rwsem_down_read_failed+0x18/0x30
[ 224.583831] ? call_rwsem_down_read_failed+0x18/0x30
[ 224.585431] down_read+0x4e/0xb0
[ 224.586487] ? iterate_supers+0x113/0x210
[ 224.587757] iterate_supers+0x113/0x210
[ 224.588984] ksys_sync+0xa5/0x170
[ 224.590073] ? sync_filesystem+0x200/0x200
[ 224.591350] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe
[ 224.593043] ? do_syscall_64+0x21/0x4e0
[ 224.594309] __ia32_sys_sync+0x9/0x10
[ 224.595540] do_syscall_64+0xd6/0x4e0
[ 224.596773] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 224.598353] RIP: 0033:0x7f774b2694d9
[ 224.599544] Code: Bad RIP value.
[ 224.600702] RSP: 002b:00007f774b945f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
[ 224.603112] RAX: ffffffffffffffda RBX: 000000000060213c RCX: 00007f774b2694d9
[ 224.605199] RDX: 00007f774b2694d9 RSI: ffffffffffffff98 RDI: 0000000000000001
[ 224.607302] RBP: 0000000000602138 R08: 0000000000000000 R09: 0000000000000000
[ 224.609402] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 224.611694] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 224.613927] 1 lock held by a.out/5476:
[ 224.615168] #0: 00000000d803423d (&type->s_umount_key#54){.+.+}, at: iterate_supers+0x113/0x210
[ 224.618055] a.out D27464 5491 1 0x00000004
[ 224.619811] Call Trace:
[ 224.620649] __schedule+0xb55/0x1dd0
[ 224.621788] ? pci_mmcfg_check_reserved+0x120/0x120
[ 224.623301] ? mark_held_locks+0xc8/0x120
[ 224.624570] ? _raw_spin_unlock_irq+0x27/0x70
[ 224.625939] schedule+0x8f/0x1b0
[ 224.627059] rwsem_down_read_failed+0x24c/0x3a0
[ 224.628508] ? rwsem_down_write_failed+0xce0/0xce0
[ 224.630102] ? block_ioctl+0xd7/0x130
[ 224.631385] ? __ia32_sys_tee+0x200/0x200
[ 224.632659] call_rwsem_down_read_failed+0x18/0x30
[ 224.634158] ? call_rwsem_down_read_failed+0x18/0x30
[ 224.635732] down_read+0x4e/0xb0
[ 224.636782] ? iterate_supers+0x113/0x210
[ 224.638064] iterate_supers+0x113/0x210
[ 224.639287] ksys_sync+0xa5/0x170
[ 224.640370] ? sync_filesystem+0x200/0x200
[ 224.641665] ? kasan_check_write+0x14/0x20
[ 224.642994] ? fput+0x18/0x130
[ 224.644073] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe
[ 224.645787] ? do_syscall_64+0x21/0x4e0
[ 224.647115] __ia32_sys_sync+0x9/0x10
[ 224.648350] do_syscall_64+0xd6/0x4e0
[ 224.649592] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 224.651178] RIP: 0033:0x7f774b2694d9
[ 224.652356] Code: Bad RIP value.
[ 224.653414] RSP: 002b:00007f774b924f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
[ 224.655692] RAX: ffffffffffffffda RBX: 0000000000602154 RCX: 00007f774b2694d9
[ 224.657831] RDX: 00007f774b2694d9 RSI: 0000000000000000 RDI: 0000000000000000
[ 224.660026] RBP: 0000000000602150 R08: 0000000000000000 R09: 0000000000000000
[ 224.662220] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 224.664520] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 224.666681] 1 lock held by a.out/5491:
[ 224.667890] #0: 00000000d803423d (&type->s_umount_key#54){.+.+}, at: iterate_supers+0x113/0x210
(...snipped...)
[ 227.999265] a.out D27464 5463 1 0x00000004
[ 228.001055] Call Trace:
[ 228.001867] __schedule+0xb55/0x1dd0
[ 228.003079] ? trace_hardirqs_on+0xd/0x10
[ 228.004417] ? pci_mmcfg_check_reserved+0x120/0x120
[ 228.006059] ? wait_woken+0x2b0/0x2b0
[ 228.007311] schedule+0x8f/0x1b0
[ 228.008433] p9_client_rpc+0x39a/0x1040
[ 228.009721] ? __free_pages_ok+0xfdc/0x1aa0
[ 228.011141] ? trace_event_raw_event_9p_client_res+0x310/0x310
[ 228.013036] ? p9_parse_header+0x12b/0x4f0
[ 228.014435] ? remove_wait_queue+0x1b0/0x1b0
[ 228.015849] ? mark_held_locks+0xc8/0x120
[ 228.017191] ? p9_fd_cancel+0x50/0x1f0
[ 228.018472] p9_client_flush+0xfa/0x1f0
[ 228.019781] ? p9_client_rpc+0x1040/0x1040
[ 228.021204] ? _raw_spin_unlock+0x22/0x30
[ 228.022543] ? p9_fd_cancel+0x50/0x1f0
[ 228.023799] p9_client_rpc+0x9d8/0x1040
[ 228.025095] ? trace_event_raw_event_9p_client_res+0x310/0x310
[ 228.026997] ? p9_idpool_put+0x31/0x40
[ 228.028255] ? mark_held_locks+0xc8/0x120
[ 228.029598] ? mark_held_locks+0xc8/0x120
[ 228.030977] ? remove_wait_queue+0x1b0/0x1b0
[ 228.032414] ? trace_hardirqs_on_caller+0x442/0x5c0
[ 228.034044] ? trace_hardirqs_on+0xd/0x10
[ 228.035434] ? p9_client_stat+0x1e4/0x4a0
[ 228.036790] ? kasan_check_read+0x11/0x20
[ 228.038127] p9_client_clunk+0x80/0x180
[ 228.039431] v9fs_mount+0x515/0x7d0
[ 228.040615] mount_fs+0x81/0x2b0
[ 228.041733] vfs_kern_mount+0x66/0x3c0
[ 228.043241] do_mount+0x366/0x2910
[ 228.044403] ? copy_mount_string+0x20/0x20
[ 228.045780] ? kmem_cache_alloc_trace+0x33c/0x750
[ 228.047370] ? copy_mount_options+0x55/0x2f0
[ 228.048814] ksys_mount+0x7e/0xd0
[ 228.049997] __x64_sys_mount+0xb9/0x150
[ 228.051328] ? trace_hardirqs_on_caller+0x442/0x5c0
[ 228.052925] do_syscall_64+0xd6/0x4e0
[ 228.054171] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 228.055834] RIP: 0033:0x7f774b2694d9
[ 228.057043] Code: Bad RIP value.
[ 228.058164] RSP: 002b:00007f774b966f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
[ 228.060583] RAX: ffffffffffffffda RBX: 0000000000602124 RCX: 00007f774b2694d9
[ 228.062873] RDX: 0000000020000340 RSI: 00000000200000c0 RDI: 0000000000000000
[ 228.065187] RBP: 0000000000602120 R08: 00000000200003c0 R09: 00007f774b966f70
[ 228.067481] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 228.069793] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 228.072166] 1 lock held by a.out/5463:
[ 228.073427] #0: 00000000d803423d (&type->s_umount_key#53/1){+.+.}, at: sget_userns+0x21d/0xb50
(...snipped...)
[ 280.160650] a.out D27464 5463 1 0x00000004
[ 280.162434] Call Trace:
[ 280.163327] __schedule+0xb55/0x1dd0
[ 280.164569] ? trace_hardirqs_on+0xd/0x10
[ 280.165915] ? pci_mmcfg_check_reserved+0x120/0x120
[ 280.167526] ? wait_woken+0x2b0/0x2b0
[ 280.168818] schedule+0x8f/0x1b0
[ 280.169893] p9_client_rpc+0x39a/0x1040
[ 280.171455] ? __free_pages_ok+0xfdc/0x1aa0
[ 280.172865] ? trace_event_raw_event_9p_client_res+0x310/0x310
[ 280.174679] ? p9_parse_header+0x12b/0x4f0
[ 280.176010] ? remove_wait_queue+0x1b0/0x1b0
[ 280.177452] ? mark_held_locks+0xc8/0x120
[ 280.178830] ? p9_fd_cancel+0x50/0x1f0
[ 280.180109] p9_client_flush+0xfa/0x1f0
[ 280.181436] ? p9_client_rpc+0x1040/0x1040
[ 280.182758] ? _raw_spin_unlock+0x22/0x30
[ 280.184050] ? p9_fd_cancel+0x50/0x1f0
[ 280.185337] p9_client_rpc+0x9d8/0x1040
[ 280.186614] ? trace_event_raw_event_9p_client_res+0x310/0x310
[ 280.188527] ? p9_idpool_put+0x31/0x40
[ 280.189799] ? mark_held_locks+0xc8/0x120
[ 280.191170] ? mark_held_locks+0xc8/0x120
[ 280.192603] ? remove_wait_queue+0x1b0/0x1b0
[ 280.194048] ? trace_hardirqs_on_caller+0x442/0x5c0
[ 280.195666] ? trace_hardirqs_on+0xd/0x10
[ 280.197010] ? p9_client_stat+0x1e4/0x4a0
[ 280.198296] ? kasan_check_read+0x11/0x20
[ 280.199574] p9_client_clunk+0x80/0x180
[ 280.200848] v9fs_mount+0x515/0x7d0
[ 280.202058] mount_fs+0x81/0x2b0
[ 280.203180] vfs_kern_mount+0x66/0x3c0
[ 280.204456] do_mount+0x366/0x2910
[ 280.205664] ? copy_mount_string+0x20/0x20
[ 280.207064] ? kmem_cache_alloc_trace+0x33c/0x750
[ 280.208618] ? copy_mount_options+0x55/0x2f0
[ 280.210027] ksys_mount+0x7e/0xd0
[ 280.211114] __x64_sys_mount+0xb9/0x150
[ 280.212389] ? trace_hardirqs_on_caller+0x442/0x5c0
[ 280.213932] do_syscall_64+0xd6/0x4e0
[ 280.215187] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 280.216849] RIP: 0033:0x7f774b2694d9
[ 280.218063] Code: Bad RIP value.
[ 280.219196] RSP: 002b:00007f774b966f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
[ 280.221658] RAX: ffffffffffffffda RBX: 0000000000602124 RCX: 00007f774b2694d9
[ 280.223981] RDX: 0000000020000340 RSI: 00000000200000c0 RDI: 0000000000000000
[ 280.226240] RBP: 0000000000602120 R08: 00000000200003c0 R09: 00007f774b966f70
[ 280.228403] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 280.230615] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 280.232804] 1 lock held by a.out/5463:
[ 280.234032] #0: 00000000d803423d (&type->s_umount_key#53/1){+.+.}, at: sget_userns+0x21d/0xb50
[ 280.236875] a.out D27464 5481 1 0x00000004
[ 280.238721] Call Trace:
[ 280.239610] __schedule+0xb55/0x1dd0
[ 280.240798] ? pci_mmcfg_check_reserved+0x120/0x120
[ 280.242368] ? mark_held_locks+0xc8/0x120
[ 280.243712] ? _raw_spin_unlock_irq+0x27/0x70
[ 280.245182] schedule+0x8f/0x1b0
[ 280.246319] rwsem_down_read_failed+0x24c/0x3a0
[ 280.247852] ? rwsem_down_write_failed+0xce0/0xce0
[ 280.249415] ? lock_downgrade+0x840/0x840
[ 280.250785] ? __ia32_sys_tee+0x200/0x200
[ 280.252169] call_rwsem_down_read_failed+0x18/0x30
[ 280.253773] ? call_rwsem_down_read_failed+0x18/0x30
[ 280.255455] down_read+0x4e/0xb0
[ 280.256585] ? iterate_supers+0x113/0x210
[ 280.257931] iterate_supers+0x113/0x210
[ 280.259220] ksys_sync+0xa5/0x170
[ 280.260386] ? sync_filesystem+0x200/0x200
[ 280.261782] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe
[ 280.263495] ? do_syscall_64+0x21/0x4e0
[ 280.264874] __ia32_sys_sync+0x9/0x10
[ 280.266117] do_syscall_64+0xd6/0x4e0
[ 280.267364] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 280.269027] RIP: 0033:0x7f774b2694d9
[ 280.270249] Code: Bad RIP value.
[ 280.271390] RSP: 002b:00007f774b945f18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
[ 280.273819] RAX: ffffffffffffffda RBX: 000000000060213c RCX: 00007f774b2694d9
[ 280.275980] RDX: 00007f774b2694d9 RSI: ffffffffffffff98 RDI: 0000000000000001
[ 280.278234] RBP: 0000000000602138 R08: 0000000000000000 R09: 0000000000000000
[ 280.280421] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 280.282597] R13: 0000000000008c00 R14: 0000000000000000 R15: 00000000756e0874
[ 280.284843] 1 lock held by a.out/5481:
[ 280.286118] #0: 00000000d803423d (&type->s_umount_key#54){.+.+}, at: iterate_supers+0x113/0x210
