INFO: task kworker/u4:2:154 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2 state:D stack:21184 pid: 154 ppid: 2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
io_schedule+0x7c/0xd0 kernel/sched/core.c:8503
rq_qos_wait+0x21d/0x330 block/blk-rq-qos.c:288
__wbt_wait block/blk-wbt.c:522 [inline]
wbt_wait+0x39e/0x680 block/blk-wbt.c:586
__rq_qos_throttle+0x61/0xa0 block/blk-rq-qos.c:72
rq_qos_throttle block/blk-rq-qos.h:203 [inline]
blk_mq_submit_bio+0x434/0x1950 block/blk-mq.c:2233
__submit_bio+0x73e/0x780 block/blk-core.c:917
__submit_bio_noacct_mq block/blk-core.c:997 [inline]
submit_bio_noacct+0x735/0x800 block/blk-core.c:1027
submit_bio+0x2c6/0x550 block/blk-core.c:1089
ext4_io_submit+0x14a/0x200 fs/ext4/page-io.c:381
ext4_writepages+0xf2f/0x2d40 fs/ext4/inode.c:2851
do_writepages+0x493/0x700 mm/page-writeback.c:2386
__writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
wb_writeback+0x45e/0xbc0 fs/fs-writeback.c:2116
wb_check_old_data_flush fs/fs-writeback.c:2216 [inline]
wb_do_writeback fs/fs-writeback.c:2269 [inline]
wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8d11efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:2/154:
#0: ffff8881447d4938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc900010cfd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
#2: ffff88814cfe20e0 (&type->s_umount_key#32){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
#3: ffff88814cfe4c58 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x213/0x2d40 fs/ext4/inode.c:2691
2 locks held by getty/3947:
#0: ffff88802cad4098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by syz.0.235/4766:
#0: ffff88802cb6a428 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88802cb6a428 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
#1: ffff88814cfe2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1817 [inline]
#1: ffff88814cfe2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1916 [inline]
#1: ffff88814cfe2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6204
#2: ffff88814cfe6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
3 locks held by syz-executor/4774:
#0: ffff88814cfe2460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff8880746303f0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:828 [inline]
#1: ffff8880746303f0 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3886
#2: ffff88814cfe6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe1b/0xe60 kernel/hung_task.c:369
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3539 Comm: syslogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3748 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3768 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3823 [inline]
RIP: 0010:__lock_acquire+0x1417/0x7d40 kernel/locking/lockdep.c:5120
Code: b8 eb 83 b5 80 46 86 c8 61 49 0f af c4 48 c1 e8 2d 48 8d 1c c5 00 50 b8 90 48 89 d8 48 c1 e8 03 48 89 44 24 30 42 80 3c 00 00 <74> 12 48 89 df e8 9f 60 61 00 49 b8 00 00 00 00 00 fc ff df 48 89
RSP: 0018:ffffc90002d3f480 EFLAGS: 00000046
RAX: 1ffffffff21baaf2 RBX: ffffffff90dd5790 RCX: ffffffff815d0753
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff91015170
RBP: ffffc90002d3f6c8 R08: dffffc0000000000 R09: 1ffffffff2202a2e
R10: dffffc0000000000 R11: fffffbfff2202a2f R12: 083b333c03f56973
R13: ffff88807dd79dc0 R14: 0000000003f56973 R15: ffff88807dd7a8d0
FS: 00007fbcfd274c80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e17e8ee168 CR3: 000000007de7c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
prepare_to_wait_exclusive+0x41/0x210 kernel/sched/wait.c:282
__skb_wait_for_more_packets+0x142/0x590 net/core/datagram.c:95
__unix_dgram_recvmsg+0x2a0/0xd50 net/unix/af_unix.c:2328
sock_recvmsg_nosec net/socket.c:969 [inline]
sock_recvmsg net/socket.c:987 [inline]
sock_read_iter+0x2c2/0x380 net/socket.c:1068
call_read_iter include/linux/fs.h:2173 [inline]
new_sync_read fs/read_write.c:404 [inline]
vfs_read+0x75e/0xd50 fs/read_write.c:485
ksys_read+0x153/0x260 fs/read_write.c:623
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbcfd3c4407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fffcd67e240 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fbcfd274c80 RCX: 00007fbcfd3c4407
RDX: 00000000000000ff RSI: 000055a9a4679950 RDI: 0000000000000000
RBP: 000055a9a4679910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055a9a46799ad
R13: 0000000000000000 R14: 000055a9a4679950 R15: 000055a9789a6d98