INFO: rcu detected stall in blkdev_open

[syzbot]

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=14b0ffdcd00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1cb1d27398c8808
dashboard link: https://syzkaller.appspot.com/bug?extid=c92c79a47f86201ba318

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+c92c79...@syzkaller.appspotmail.com

audit: type=1804 audit(5907400426.337:362): pid=4355 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.5" name="/root/syzkaller-testdir233255044/syzkaller.0qrakC/10/file1/file0" dev="sda1" ino=16705 res=1
md: could not open unknown-block(0,76).
md: md_import_device returned -6
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: (detected by 0, t=10502 jiffies, g=133725, q=293)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295036654-4295026152), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.5 R running task 25552 4355 3630 0x00000000
Call Trace:
<IRQ>
sched_show_task.cold+0x332/0x396 kernel/sched/core.c:5337
print_other_cpu_stall kernel/rcu/tree.c:1430 [inline]
check_cpu_stall kernel/rcu/tree.c:1557 [inline]
__rcu_pending kernel/rcu/tree.c:3293 [inline]
rcu_pending kernel/rcu/tree.c:3336 [inline]
rcu_check_callbacks.cold+0xb37/0xe19 kernel/rcu/tree.c:2682
update_process_times+0x2a/0x70 kernel/time/timer.c:1650
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:168
tick_sched_timer+0xfc/0x290 kernel/time/tick-sched.c:1278
__run_hrtimer kernel/time/hrtimer.c:1401 [inline]
__hrtimer_run_queues+0x3f6/0xe60 kernel/time/hrtimer.c:1463
hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1521
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
smp_apic_timer_interrupt+0x10c/0x550 arch/x86/kernel/apic/apic.c:1092
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
</IRQ>
RIP: 0010:lock_is_held_type+0x25/0x210 kernel/locking/lockdep.c:3938
Code: 00 00 00 00 90 48 b8 00 00 00 00 00 fc ff df 41 54 55 48 89 fd 53 65 48 8b 1c 25 80 df 01 00 48 8d bb 84 08 00 00 48 83 ec 08 <48> 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0
RSP: 0018:ffff8880279677e0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff88809a906540 RCX: 0000000000000000
RDX: 0000000000000004 RSI: 00000000ffffffff RDI: ffff88809a906dc4
RBP: ffffffff89f85de0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffff8880a47c0488
R13: ffff8880b1bc61d0 R14: 0000000000000000 R15: ffff8880b1bc6118
__disk_get_part+0x16d/0x1e0 block/genhd.c:103
disk_get_part+0x79/0x180 block/genhd.c:125
__blkdev_get+0x2f6/0x1480 fs/block_dev.c:1488
blkdev_get+0xb0/0x940 fs/block_dev.c:1627
blkdev_open+0x202/0x290 fs/block_dev.c:1788
do_dentry_open+0x4aa/0x1160 fs/open.c:796
do_last fs/namei.c:3421 [inline]
path_openat+0x793/0x2df0 fs/namei.c:3537
do_filp_open+0x18c/0x3f0 fs/namei.c:3567
do_sys_open+0x3b3/0x520 fs/open.c:1085
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465b09
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6f61152188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465b09
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: ffffffffffffff9c
RBP: 00000000004b069f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffcff0b07df R14: 00007f6f61152300 R15: 0000000000022000
rcu: rcu_preempt kthread starved for 10502 jiffies! g133725 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt R running task 29208 10 2 0x80000000
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_timeout+0x4cf/0xfe0 kernel/time/timer.c:1818
rcu_gp_kthread+0xdad/0x21c0 kernel/rcu/tree.c:2202
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.