INFO: task hung in blk_trace_ioctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10623a2e080000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=4331197d66398970e746
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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+433119...@syzkaller.appspotmail.com

INFO: task syz-executor.2:28960 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D27296 28960 28497 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:1016 [inline]
__mutex_lock+0x5f0/0x1190 kernel/locking/mutex.c:1078
blk_trace_ioctl+0xd2/0x290 kernel/trace/blktrace.c:745
blkdev_ioctl+0x112/0x1a80 block/ioctl.c:587
block_ioctl+0xe9/0x130 fs/block_dev.c:1906
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb816ce6209
Code: Bad RIP value.
RSP: 002b:00007fb8155f8168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb816df91d0 RCX: 00007fb816ce6209
RDX: 0000000020000000 RSI: 00000000c0481273 RDI: 0000000000000006
RBP: 00007fb816d40161 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc5526ca0f R14: 00007fb8155f8300 R15: 0000000000022000

Showing all locks held in the system:
1 lock held by khungtaskd/1571:
#0: 00000000422c2324 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441
2 locks held by systemd-udevd/4701:
#0: 0000000035884c02 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x1d0/0x1480 fs/block_dev.c:1478
#1: 00000000bc466c61 (loop_ctl_mutex){+.+.}, at: lo_open+0x19/0xd0 drivers/block/loop.c:1771
1 lock held by in:imklog/7809:
#0: 00000000c10033a6 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
2 locks held by syz-executor.1/24785:
#0: 00000000748c8206 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x1d0/0x1480 fs/block_dev.c:1478
#1: 00000000bc466c61 (loop_ctl_mutex){+.+.}, at: lo_open+0x19/0xd0 drivers/block/loop.c:1771
2 locks held by syz-executor.2/28956:
1 lock held by syz-executor.2/28960:
#0: 00000000eb8733f9 (&q->blk_trace_mutex){+.+.}, at: blk_trace_ioctl+0xd2/0x290 kernel/trace/blktrace.c:745
2 locks held by syz-executor.4/2775:
5 locks held by syz-executor.0/2810:
3 locks held by syz-executor.3/2808:
2 locks held by syz-executor.2/2815:
#0: 00000000fcc738d3 (&bdev->bd_mutex){+.+.}, at: __blkdev_put+0xfc/0x870 fs/block_dev.c:1806
#1: 00000000bc466c61 (loop_ctl_mutex){+.+.}, at: lo_release+0x1a/0x1f0 drivers/block/loop.c:1790

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

NMI backtrace for cpu 1
CPU: 1 PID: 1571 Comm: khungtaskd Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 28956 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:trace_hardirqs_off+0x64/0x200 kernel/trace/trace_preemptirq.c:43
Code: 00 00 10 00 31 ff 89 de e8 39 d9 fa ff 85 db 75 14 e8 c0 d7 fa ff 4c 8b 6c 24 28 0f 1f 44 00 00 e8 b1 d7 fa ff e8 ac d7 fa ff <48> 8b 7c 24 28 5b 5d 41 5c 41 5d 41 5e e9 4a ae e3 ff e8 95 d7 fa
RSP: 0018:ffff888052ae7a18 EFLAGS: 00000093
RAX: ffff8880a3d6c680 RBX: 0000000000000000 RCX: ffffffff8167ada7
RDX: 0000000000000000 RSI: ffffffff8167adc4 RDI: 0000000000000005
RBP: 000000000003a4a1 R08: ffffed1007494200 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: ffffea0000e92840
R13: ffffffff817ee9a8 R14: ffffed101562fcdc R15: ffffc90005e37578
FS: 00007fb815619700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0a27eeefc0 CR3: 0000000057d2a000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
free_unref_page+0x98/0x170 mm/page_alloc.c:2815
relay_destroy_buf+0x11f/0x380 kernel/relay.c:216
relay_remove_buf kernel/relay.c:236 [inline]
kref_put include/linux/kref.h:70 [inline]
relay_close_buf+0x104/0x140 kernel/relay.c:499
relay_close kernel/relay.c:854 [inline]
relay_close+0x149/0x480 kernel/relay.c:840
blk_trace_free+0x81/0x130 kernel/trace/blktrace.c:317
blk_trace_cleanup kernel/trace/blktrace.c:343 [inline]
__blk_trace_remove+0x8b/0x100 kernel/trace/blktrace.c:356
blk_trace_ioctl+0x23b/0x290 kernel/trace/blktrace.c:764
blkdev_ioctl+0x112/0x1a80 block/ioctl.c:587
block_ioctl+0xe9/0x130 fs/block_dev.c:1906
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fb816ce6209
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb815619168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb816df9100 RCX: 00007fb816ce6209
RDX: 0000000000000000 RSI: 0000000000001276 RDI: 0000000000000006
RBP: 00007fb816d40161 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc5526ca0f R14: 00007fb815619300 R15: 0000000000022000


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[syzbot]

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