INFO: task hung in truncate_inode_pages_range

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8961076e Linux 4.14.207
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15918841500000
kernel config: https://syzkaller.appspot.com/x/.config?x=44f5233cc1f5c95d
dashboard link: https://syzkaller.appspot.com/bug?extid=a6720bebbec2809156b3
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=164b63f6500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=171b06f6500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a6720b...@syzkaller.appspotmail.com

block nbd0: Device being setup by another task
block nbd0: Device being setup by another task
block nbd0: Device being setup by another task
block nbd0: Device being setup by another task
INFO: task syz-executor354:27091 blocked for more than 140 seconds.
Not tainted 4.14.207-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor354 D29072 27091 8027 0x80000002
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3384
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
io_schedule+0xb5/0x120 kernel/sched/core.c:5036
wait_on_page_bit_common mm/filemap.c:1025 [inline]
__lock_page+0x27b/0x380 mm/filemap.c:1197
lock_page include/linux/pagemap.h:479 [inline]
truncate_inode_pages_range+0x8d2/0x13e0 mm/truncate.c:399
kill_bdev fs/block_dev.c:98 [inline]
__blkdev_put+0x24c/0x800 fs/block_dev.c:1797
blkdev_close+0x86/0xb0 fs/block_dev.c:1875
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xa44/0x2850 kernel/exit.c:868
do_group_exit+0x100/0x2e0 kernel/exit.c:965
get_signal+0x38d/0x1ca0 kernel/signal.c:2423
do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:814
exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x44a5a9
RSP: 002b:00007f658275cdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dbc48 RCX: 000000000044a5a9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc48
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007ffdc4c0faaf R14: 00007f658275d9c0 R15: 20c49ba5e353f7cf
INFO: task systemd-udevd:27093 blocked for more than 140 seconds.
Not tainted 4.14.207-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
systemd-udevd D28912 27093 4629 0x00000104
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3384
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x669/0x1310 kernel/locking/mutex.c:893
__blkdev_get+0x191/0x1090 fs/block_dev.c:1455
blkdev_get+0x88/0x890 fs/block_dev.c:1611
blkdev_open+0x1cc/0x250 fs/block_dev.c:1772
do_dentry_open+0x44b/0xec0 fs/open.c:777
vfs_open+0x105/0x220 fs/open.c:888
do_last fs/namei.c:3428 [inline]
path_openat+0x628/0x2970 fs/namei.c:3569
do_filp_open+0x179/0x3c0 fs/namei.c:3603
do_sys_open+0x296/0x410 fs/open.c:1081
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f22146e7840
RSP: 002b:00007ffef97cecc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000055ea3e1fc980 RCX: 00007f22146e7840
RDX: 000055ea3d0cafe3 RSI: 00000000000a0800 RDI: 000055ea3e1ed690
RBP: 00007ffef97cee40 R08: 000055ea3d0ca670 R09: 0000000000000010
R10: 000055ea3d0cad0c R11: 0000000000000246 R12: 00007ffef97ced90
R13: 000055ea3e1ed240 R14: 0000000000000003 R15: 000000000000000e

Showing all locks held in the system:
1 lock held by khungtaskd/1530:
#0: (tasklist_lock){.+.+}, at: [<ffffffff81430cb4>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by syz-executor354/27091:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffff81961118>] __blkdev_put+0xd8/0x800 fs/block_dev.c:1790
1 lock held by systemd-udevd/27093:
#0: (&bdev->bd_mutex){+.+.}, at: [<ffffffff81962da1>] __blkdev_get+0x191/0x1090 fs/block_dev.c:1455

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

NMI backtrace for cpu 0
CPU: 0 PID: 1530 Comm: khungtaskd Not tainted 4.14.207-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5b9/0xb40 kernel/hung_task.c:274
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff8720791e


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