INFO: task syz.3.812:12304 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.812       state:D stack:25640 pid:12304 tgid:12302 ppid:5597   task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x16dc/0x5500 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 schedule_timeout+0xc0/0x2c0 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2ca/0x5e0 kernel/sched/completion.c:153
 kthread_flush_worker+0x138/0x1a0 kernel/kthread.c:1579
 __alloc_workqueue+0x16b2/0x2060 kernel/workqueue.c:5924
 alloc_workqueue_va kernel/workqueue.c:5946 [inline]
 alloc_workqueue_noprof+0xe3/0x210 kernel/workqueue.c:5962
 btrfs_init_workqueues+0x218/0x630 fs/btrfs/disk-io.c:1974
 open_ctree+0x1503/0x41c0 fs/btrfs/disk-io.c:3523
 btrfs_fill_super fs/btrfs/super.c:982 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1971 [inline]
 btrfs_get_tree_subvol fs/btrfs/super.c:2114 [inline]
 btrfs_get_tree+0x1084/0x1980 fs/btrfs/super.c:2148
 vfs_get_tree+0x92/0x2a0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 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: 0033:0x7f2170b3f10a
RSP: 002b:00007f216ed95e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f216ed95ee0 RCX: 00007f2170b3f10a
RDX: 0000200000005100 RSI: 0000200000005140 RDI: 00007f216ed95ea0
RBP: 0000200000005100 R08: 00007f216ed95ee0 R09: 0000000000018000
R10: 0000000000018000 R11: 0000000000000246 R12: 0000200000005140
R13: 00007f216ed95ea0 R14: 00000000000050d4 R15: 0000200000005180
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:0/12:
 #0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #1: ffffc90000117c40 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffffc90000117c40 ((reaper_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
1 lock held by khungtaskd/37:
 #0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:9/1073:
 #0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #1: ffffc90006167c40 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffffc90006167c40 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
2 locks held by getty/5353:
 #0: ffff88803563b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003cc62e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
3 locks held by udevd/5824:
1 lock held by syz.3.812/12304:
 #0: ffff88806221a0d0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: alloc_super fs/super.c:345 [inline]
 #0: ffff88806221a0d0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: sget_fc+0x938/0x1910 fs/super.c:766
1 lock held by syz.1.850/12640:
 #0: ffff8880299200d0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: alloc_super fs/super.c:345 [inline]
 #0: ffff8880299200d0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: sget_fc+0x938/0x1910 fs/super.c:766
5 locks held by syz.5.995/13909:
1 lock held by syz.4.996/13934:
3 locks held by syz.4.996/13940:
4 locks held by syz.0.997/13936:
3 locks held by syz.6.993/13939:
2 locks held by syz.6.993/13944:
 #0: ffff88803fc1a500 (sb_writers#15){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff8880377bcd08 (&type->i_mutex_dir_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff8880377bcd08 (&type->i_mutex_dir_key#9){++++}-{4:4}, at: open_last_lookups fs/namei.c:4605 [inline]
 #1: ffff8880377bcd08 (&type->i_mutex_dir_key#9){++++}-{4:4}, at: path_openat+0xae9/0x3850 fs/namei.c:4860
3 locks held by syz.6.993/13945:
1 lock held by udevadm/13938:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 13940 Comm: syz.4.996 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:unwind_next_frame+0x6fc/0x2550 arch/x86/kernel/unwind_orc.c:527
Code: 93 17 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 a3 17 00 00 0f b7 1a c1 eb 0b 80 e3 01 48 8b 04 24 42 0f b6 04 20 <84> c0 0f 85 ac 17 00 00 49 8d 46 35 88 18 0f b7 1a 83 e3 0f 83 fb
RSP: 0018:ffffc90006f671a0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8fd18cf8
RDX: ffffffff904e4e08 RSI: ffffffff904e4e04 RDI: ffffffff8bca6620
RBP: ffffc90006f67280 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8e1c3000 R12: dffffc0000000000
R13: ffffffff904e4e04 R14: ffffc90006f67248 R15: 1ffff92000dece49
FS:  00007f6f192656c0(0000) GS:ffff888125c45000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f05c6363ff8 CR3: 0000000021aaa000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x124/0x230 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4b0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x262a/0x26a0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_pages_mpol+0xce/0x280 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x3b/0x1e0 mm/mempolicy.c:2509
 shmem_alloc_folio mm/shmem.c:1907 [inline]
 shmem_alloc_and_add_folio mm/shmem.c:1949 [inline]
 shmem_get_folio_gfp+0x6ee/0x1c40 mm/shmem.c:2502
 shmem_get_folio mm/shmem.c:2608 [inline]
 shmem_write_begin+0x166/0x320 mm/shmem.c:3239
 generic_perform_write+0x2ad/0x8b0 mm/filemap.c:4358
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3414
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 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: 0033:0x7f6f1afee6ce
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f6f19264da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6f192656c0 RCX: 00007f6f1afee6ce
RDX: 0000000000200000 RSI: 00007f6f10e45000 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00007f6f19264ee0 R14: 00007f6f19264ea0 R15: 00007f6f10e45000
 </TASK>