INFO: task syz.7.1410:12544 blocked for more than 143 seconds.
      Not tainted 6.16.0-next-20250731-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.1410      state:D stack:23456 pid:12544 tgid:12543 ppid:9914   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1360 kernel/locking/mutex.c:760
 sync_bdevs+0x1ac/0x340 block/bdev.c:1288
 ksys_sync+0xb9/0x150 fs/sync.c:105
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f81a918eb69
RSP: 002b:00007f81a9fcb038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f81a93b5fa0 RCX: 00007f81a918eb69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f81a93b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f81a93b5fa0 R15: 00007ffc5aa2bf98
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:4/78:
 #0: ffff8880b8639f58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:644
 #1: ffff8880b8624008 (per_cpu_ptr(&psi_seq, cpu)){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:937
2 locks held by getty/5606:
 #0: ffff88814d7450a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036c62f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by udevd/5845:
 #0: ffff8880250e0358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:945
1 lock held by syz.7.1410/12544:
 #0: ffff8880250e0358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340 block/bdev.c:1288
2 locks held by syz-executor/13054:
 #0: ffff8880787920e0 (&type->s_umount_key#72){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880787920e0 (&type->s_umount_key#72){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880787920e0 (&type->s_umount_key#72){++++}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
 #1: ffffffff8e13f880 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570 kernel/rcu/tree.c:3815
1 lock held by syz.6.1923/14626:
2 locks held by dhcpcd-run-hook/14643:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-next-20250731-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 14626 Comm: syz.6.1923 Not tainted 6.16.0-next-20250731-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rcu_is_watching+0x0/0xb0 kernel/rcu/tree.c:747
Code: c7 c7 a0 ed 13 8e e8 df 33 59 03 eb cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 41 57 41 56 53 65 ff 05 b0 71 f7 10 e8 1b e3 d0 09 89
RSP: 0018:ffffc90003c2f3c8 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffffffff822a9cd9 RCX: ffff88801c73da00
RDX: 0000000000000000 RSI: ffffffff8db7a779 RDI: ffffffff8be34100
RBP: 0000000000000013 R08: 0000000000000000 R09: ffffffff822a9cd9
R10: dffffc0000000000 R11: fffff940001aa8f1 R12: ffffea0000d54780
R13: 0000000000000001 R14: dffffc0000000000 R15: ffff88813fffb400
FS:  00007f33534aa6c0(0000) GS:ffff888125d43000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f47d87157e8 CR3: 0000000042c62000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_lock include/linux/rcupdate.h:842 [inline]
 __lruvec_stat_mod_folio+0xa7/0x2f0 mm/memcontrol.c:785
 shmem_update_stats+0xeb/0x120 mm/shmem.c:894
 shmem_add_to_page_cache+0x8b3/0xba0 mm/shmem.c:945
 shmem_alloc_and_add_folio+0x846/0xf60 mm/shmem.c:1973
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2597
 shmem_fault+0x179/0x390 mm/shmem.c:2798
 __do_fault+0x138/0x390 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x3611/0x5440 mm/memory.c:6195
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x1699/0x2ce0 mm/gup.c:1446
 populate_vma_page_range+0x29f/0x3a0 mm/gup.c:1880
 __mm_populate+0x24c/0x380 mm/gup.c:1983
 mm_populate include/linux/mm.h:3390 [inline]
 vm_mmap_pgoff+0x387/0x4d0 mm/util.c:585
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f335258eb69
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f33534aa038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f33527b5fa0 RCX: 00007f335258eb69
RDX: b635773f06ebbee2 RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f3352611df1 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f33527b5fa0 R15: 00007ffdf4c3dcf8
 </TASK>