syzbot

INFO: task kworker/u8:2:37 blocked in I/O wait for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:23616 pid:37    tgid:37    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7282
 io_schedule+0x7f/0xd0 kernel/sched/core.c:8109
 TXN_SLEEP_DROP_LOCK fs/jfs/jfs_txnmgr.c:125 [inline]
 txBegin+0x27d/0xc00 fs/jfs/jfs_txnmgr.c:376
 jfs_commit_inode+0x1b3/0x530 fs/jfs/inode.c:107
 jfs_write_inode+0x145/0x220 fs/jfs/inode.c:138
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x75a/0x10e0 fs/fs-writeback.c:1825
 writeback_sb_inodes+0x979/0x19d0 fs/fs-writeback.c:2054
 wb_writeback+0x445/0xb00 fs/fs-writeback.c:2239
 wb_do_writeback fs/fs-writeback.c:2386 [inline]
 wb_workfn+0x3f8/0xf10 fs/fs-writeback.c:2426
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 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>
INFO: task syz-executor:5973 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22568 pid:5973  tgid:5973  ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7282
 wb_wait_for_completion+0x3e8/0x790 fs/fs-writeback.c:227
 __writeback_inodes_sb_nr+0x24b/0x2c0 fs/fs-writeback.c:2845
 sync_filesystem+0xa3/0x230 fs/sync.c:54
 generic_shutdown_super+0x77/0x2d0 fs/super.c:625
 kill_block_super+0x44/0x90 fs/super.c:1725
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f49abf9da57
RSP: 002b:00007ffc33ac4d78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f49ac032048 RCX: 00007f49abf9da57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc33ac4e30
RBP: 00007ffc33ac4e30 R08: 00007ffc33ac5e30 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc33ac5ec0
R13: 00007f49ac032048 R14: 000000000005d3dd R15: 00007ffc33ac5f00
 </TASK>

Showing all locks held in the system:
1 lock held by ksoftirqd/0/15:
 #0: ffff8880b863ae60 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:652
1 lock held by khungtaskd/32:
 #0: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:2/37:
 #0: ffff88801f2f6940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801f2f6940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc90000ad7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc90000ad7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
2 locks held by getty/5579:
 #0: ffff88803748e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/5973:
 #0: ffff888034a800d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888034a800d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888034a800d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
2 locks held by kworker/u8:4/5994:
 #0: ffff88801f2f6940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801f2f6940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc900045c7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc900045c7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
1 lock held by syz-executor/6110:
 #0: ffff88802e2040d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802e2040d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88802e2040d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:508
2 locks held by syz.2.355/6459:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 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+0xfd3/0x1030 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>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6459 Comm: syz.2.355 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:record_print_text+0x4/0x450 kernel/printk/printk.c:1416
Code: 48 89 d3 e8 7e 83 8b 00 48 89 da e9 c5 fd ff ff 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <55> 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec 00 01
RSP: 0018:ffffc90003126a38 EFLAGS: 00000293
RAX: ffffffff81a41f31 RBX: 0000000000000004 RCX: ffff888031ab9ec0
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffc90003126b80
RBP: ffffc90003126c10 R08: ffff888031ab9ec0 R09: 0000000000000003
R10: 00000000ffffffff R11: 0000000000000000 R12: ffffc90003126b00
R13: 1ffff92000624d62 R14: 000000000000000f R15: 1ffff92000624d54
FS:  0000555585250500(0000) GS:ffff88812522b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f66559ff000 CR3: 00000000724c3000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 printk_get_next_message+0x29c/0x880 kernel/printk/printk.c:3072
 console_emit_next_record kernel/printk/printk.c:3137 [inline]
 console_flush_one_record kernel/printk/printk.c:3269 [inline]
 console_flush_all+0x501/0xb20 kernel/printk/printk.c:3343
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
 vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 set_capacity_and_notify+0x2c5/0x320 block/genhd.c:93
 loop_set_size+0x44/0xb0 drivers/block/loop.c:220
 loop_configure+0x9ac/0xdf0 drivers/block/loop.c:1079
 lo_ioctl+0x447/0x1fb0 drivers/block/loop.c:1534
 blkdev_ioctl+0x5e3/0x740 block/ioctl.c:797
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f665d99c4ab
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffc59d11150 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f665d99c4ab
RDX: 0000000000000003 RSI: 0000000000004c00 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffc59d11280 R14: 00007ffc59d11240 R15: 00007f6654a00000
 </TASK>