INFO: task systemd-udevd:18154 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc3-next-20200701-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
systemd-udevd   D28048 18154   3875 0x80004106
Call Trace:
 context_switch kernel/sched/core.c:3445 [inline]
 __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169
 schedule+0xd0/0x2a0 kernel/sched/core.c:4244
 io_schedule+0xb5/0x120 kernel/sched/core.c:5935
 wait_on_page_bit_common+0x34f/0xda0 mm/filemap.c:1124
 lock_page include/linux/pagemap.h:580 [inline]
 truncate_inode_pages_range+0xb69/0x16a0 mm/truncate.c:446
 kill_bdev fs/block_dev.c:86 [inline]
 __blkdev_put+0x2b4/0x890 fs/block_dev.c:1894
 blkdev_close+0x8c/0xb0 fs/block_dev.c:1969
 __fput+0x33c/0x880 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:123
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xb72/0x2a40 kernel/exit.c:806
 do_group_exit+0x125/0x310 kernel/exit.c:904
 get_signal+0x428/0x1fc0 kernel/signal.c:2739
 do_signal+0x82/0x2520 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:212 [inline]
 __prepare_exit_to_usermode+0x156/0x1f0 arch/x86/entry/common.c:246
 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f8f0edff210
Code: Bad RIP value.
RSP: 002b:00007fff2cfac4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffffc RBX: 000055e97f7b12b0 RCX: 00007f8f0edff210
RDX: 0000000000000400 RSI: 000055e97f7b12d8 RDI: 000000000000000f
RBP: 000055e97f7ae010 R08: 00007f8f0ede9fa8 R09: 0000000000000430
R10: 000000000000006d R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000400 R14: 000055e97f7ae060 R15: 0000000000000400

Showing all locks held in the system:
1 lock held by khungtaskd/1148:
 #0: ffffffff89bc3000 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
1 lock held by in:imklog/6497:
 #0: ffff8880a010d5f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:928
1 lock held by syz-executor.0/15604:
 #0: ffffffff8a029670 (key_types_sem){++++}-{3:3}, at: key_type_lookup+0x1a/0xf0 security/keys/key.c:704
1 lock held by systemd-udevd/18154:
 #0: ffff88808aa3d100 (&bdev->bd_mutex){+.+.}-{3:3}, at: __blkdev_put+0xfc/0x890 fs/block_dev.c:1887

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

NMI backtrace for cpu 1
CPU: 1 PID: 1148 Comm: khungtaskd Not tainted 5.8.0-rc3-next-20200701-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+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
 watchdog+0xd89/0xf30 kernel/hung_task.c:339
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3856 Comm: systemd-journal Not tainted 5.8.0-rc3-next-20200701-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unwind_next_frame+0x4c/0x1f90 arch/x86/kernel/unwind_orc.c:424
Code: 40 b3 8a b5 41 48 8d 5c 24 40 48 c7 44 24 48 d8 69 67 89 48 c1 eb 03 48 c7 44 24 50 e0 3b 33 81 48 8d 14 03 c7 02 f1 f1 f1 f1 <c7> 42 04 00 f3 f3 f3 48 89 fa 65 48 8b 34 25 28 00 00 00 48 89 b4
RSP: 0018:ffffc900015f7920 EFLAGS: 00000a02
RAX: dffffc0000000000 RBX: 1ffff920002bef2c RCX: ffffc900015f7ad8
RDX: fffff520002bef2c RSI: 1ffff920002bef4b RDI: ffffc900015f7a48
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffc900015f7a48
R10: fffff520002bef54 R11: 0000000000000000 R12: fffff520002bef4b
R13: fffff520002bef4a R14: ffffc900015f7a80 R15: ffffc900015f7a48
FS:  00007f2bcab688c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2bc8462000 CR3: 0000000094903000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __unwind_start+0x4dd/0x7c0 arch/x86/kernel/unwind_orc.c:698
 unwind_start arch/x86/include/asm/unwind.h:60 [inline]
 arch_stack_walk+0x5e/0xf0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:494
 slab_post_alloc_hook mm/slab.h:535 [inline]
 slab_alloc mm/slab.c:3316 [inline]
 kmem_cache_alloc+0x148/0x550 mm/slab.c:3486
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags fs/namei.c:2646 [inline]
 user_path_at_empty+0xa1/0x100 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x129/0x820 fs/open.c:423
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f2bc9e249c7
Code: Bad RIP value.
RSP: 002b:00007ffe240deb58 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00007ffe240e1b80 RCX: 00007f2bc9e249c7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000560e8e38e9a3
RBP: 00007ffe240deca0 R08: 0000560e8e3843e5 R09: 0000000000000018
R10: 0000000000000069 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000560e8f17b8a0 R15: 00007ffe240df190