INFO: task syz.0.26:6160 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.26        state:D stack:25016 pid:6160  tgid:6159  ppid:5794   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5504 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228
 __schedule_loop kernel/sched/core.c:7307 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7322
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7379
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
 udf_table_free_blocks fs/udf/balloc.c:376 [inline]
 udf_free_blocks+0xa8c/0x1900 fs/udf/balloc.c:678
 udf_delete_aext+0x4f5/0xc00 fs/udf/inode.c:2381
 udf_table_prealloc_blocks fs/udf/balloc.c:544 [inline]
 udf_prealloc_blocks+0xbd4/0x10e0 fs/udf/balloc.c:702
 udf_prealloc_extents fs/udf/inode.c:1058 [inline]
 inode_getblk fs/udf/inode.c:916 [inline]
 udf_map_block+0x1e7f/0x4280 fs/udf/inode.c:453
 __udf_get_block+0x52/0x250 fs/udf/inode.c:467
 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2123
 block_write_begin+0x8d/0x120 fs/buffer.c:2234
 udf_write_begin+0x118/0x270 fs/udf/inode.c:261
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4363
 __generic_file_write_iter+0x1ae/0x230 mm/filemap.c:4477
 udf_file_write_iter+0x2e8/0x6c0 fs/udf/file.c:112
 iter_file_splice_write+0xa31/0x1240 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1159
 splice_direct_to_actor+0x57b/0xcb0 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1228
 do_sendfile+0x52e/0x7c0 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1418
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f861159a679
RSP: 002b:00007f861250e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f8611805fa0 RCX: 00007f861159a679
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000004
RBP: 00007f861162dee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000800000009 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8611806038 R14: 00007f8611805fa0 R15: 00007ffc0b333d98
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 26 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>