INFO: task syz-executor.5:653 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D29912   653  32729 0x00000004
 ffff8800a3518000 ffff8801ceaf3700 ffff88009bf35d80 ffff8801d1a4df00
 ffff8801db721018 ffff880189e97b48 ffffffff828075c2 0000000000000286
 0000000000000002 0000000041b58ab3 00ffffff82e2b9d2 ffff8801db7218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815a17c9>] wb_wait_for_completion+0x149/0x1b0 fs/fs-writeback.c:221
 [<ffffffff815a1f6b>] sync_inodes_sb+0x1ab/0x9d0 fs/fs-writeback.c:2412
 [<ffffffff815b1653>] sync_inodes_one_sb+0x43/0x60 fs/sync.c:73
 [<ffffffff81515040>] iterate_supers+0x130/0x260 fs/super.c:593
 [<ffffffff815b1f62>] sys_sync+0xa2/0x170 fs/sync.c:112
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2024:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
4 locks held by kworker/u4:17/22231:
 #0:  ("writeback"){++++.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#32){++++.+}, at: [<ffffffff815149f0>] trylock_super+0x20/0xf0 fs/super.c:393
 #3:  (&sbi->s_journal_flag_rwsem){.+.+.+}, at: [<ffffffff81433d3f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2331
1 lock held by syz-executor.5/653:
 #0:  (&type->s_umount_key#32){++++.+}, at: [<ffffffff81514ff1>] iterate_supers+0xe1/0x260 fs/super.c:591
1 lock held by syz-executor.5/654:
 #0:  (&type->s_umount_key#32){++++.+}, at: [<ffffffff81514ff1>] iterate_supers+0xe1/0x260 fs/super.c:591

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4df89>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4df1c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810984b4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c65d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c65d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c65d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c65d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 20734 Comm: syz-executor.1 Not tainted 4.9.141+ #1
task: ffff88009aae97c0 task.stack: ffff88009a4b0000
RIP: 0010:[<ffffffff812073a0>] 
c [<ffffffff812073a0>] trace_hardirqs_on+0x0/0x10 kernel/locking/lockdep.c:2742
RSP: 0018:ffff88009a4b77d0  EFLAGS: 00000006
RAX: 00000000024080c0 RBX: ffff8801da4013c0 RCX: 000000000000000c
RDX: 00000000ffffffff RSI: 0000000000000000 RDI: ffff8801da4013c0
RBP: ffff88009a4b7820 R08: ffff88009aaea070 R09: 0000000000000001
R10: ffff8801ca191750 R11: 0000000000000001 R12: 00000000024080c0
R13: 00000000024000c0 R14: ffff8801db724670 R15: 0000000000000000
FS:  00007f4741b29700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000015f2308 CR3: 00000000aca63000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff814eb783
c 000000000000000c
c 024080c000000000
c 0000000000000000
c
 4a94b9a696c61ca1
c 00000000ffffffff
c 00000000024080c0
c ffff8801da4013c0
c
 ffff8801db724670
c 0000000000000000
c ffff88009a4b78f8
c ffffffff814ed97d
c
Call Trace:
 [<ffffffff814ed97d>] new_slab_objects mm/slub.c:2419 [inline]
 [<ffffffff814ed97d>] ___slab_alloc.constprop.33+0x2ed/0x470 mm/slub.c:2576
 [<ffffffff814edb50>] __slab_alloc.isra.25.constprop.32+0x50/0xa0 mm/slub.c:2618
 [<ffffffff814ee42e>] slab_alloc_node mm/slub.c:2681 [inline]
 [<ffffffff814ee42e>] slab_alloc mm/slub.c:2723 [inline]
 [<ffffffff814ee42e>] __kmalloc+0x26e/0x310 mm/slub.c:3737
 [<ffffffff815ae043>] kmalloc_array include/linux/slab.h:582 [inline]
 [<ffffffff815ae043>] kcalloc include/linux/slab.h:593 [inline]
 [<ffffffff815ae043>] iter_file_splice_write+0x143/0xb30 fs/splice.c:711
 [<ffffffff815a9ab8>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff815a9ab8>] direct_splice_actor+0x128/0x190 fs/splice.c:1037
 [<ffffffff815ab6c1>] splice_direct_to_actor+0x2c1/0x7e0 fs/splice.c:992
 [<ffffffff815abd83>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff8150d780>] do_sendfile+0x4f0/0xc30 fs/read_write.c:1393
 [<ffffffff8150f7f1>] SYSC_sendfile64 fs/read_write.c:1448 [inline]
 [<ffffffff8150f7f1>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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