INFO: task syz.2.1309:16591 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1309      state:D stack:25624 pid:16591 tgid:16589 ppid:10951  task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x145f/0x5070 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6960
 schedule_timeout+0x9a/0x270 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+0x2bf/0x5d0 kernel/sched/completion.c:153
 kthread_flush_worker+0x10e/0x160 kernel/kthread.c:1559
 __alloc_workqueue+0x1485/0x1b80 kernel/workqueue.c:5797
 alloc_workqueue_noprof+0xd4/0x210 kernel/workqueue.c:5820
 btrfs_alloc_workqueue+0x1ec/0x2d0 fs/btrfs/async-thread.c:112
 btrfs_init_workqueues+0x2f9/0x680 fs/btrfs/disk-io.c:1983
 open_ctree+0x141d/0x3d20 fs/btrfs/disk-io.c:3411
 btrfs_fill_super fs/btrfs/super.c:981 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1944 [inline]
 btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline]
 btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2121
 vfs_get_tree+0x92/0x2a0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3712
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f053ef80eea
RSP: 002b:00007f053d1dde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f053d1ddef0 RCX: 00007f053ef80eea
RDX: 00002000000004c0 RSI: 00002000000015c0 RDI: 00007f053d1ddeb0
RBP: 00002000000004c0 R08: 00007f053d1ddef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00002000000015c0
R13: 00007f053d1ddeb0 R14: 000000000000559e R15: 0000200000000180
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
 #0: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8d5ae940 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5555:
 #0: ffff88814e8be0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e762e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x44f/0x1460 drivers/tty/n_tty.c:2211
3 locks held by kworker/u8:29/16276:
 #0: ffff888140abb138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888140abb138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
 #1: ffffc90016eefbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90016eefbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
 #2: ffff888030a5e0d0 (&type->s_umount_key#90){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
1 lock held by syz.2.1309/16591:
 #0: ffff88806329e0d0 (&type->s_umount_key#50/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
2 locks held by syz.5.1389/17132:
4 locks held by syz.3.1541/18206:
3 locks held by syz.9.1540/18209:
4 locks held by syz.4.1536/18211:
2 locks held by dhcpcd-run-hook/18214:
4 locks held by syz.6.1542/18217:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:160 [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:346 [inline]
 watchdog+0xf95/0xfe0 kernel/hung_task.c:515
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 18206 Comm: syz.3.1541 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:folio_test_hugetlb include/linux/page-flags.h:1054 [inline]
RIP: 0010:__folio_rmap_sanity_checks include/linux/rmap.h:401 [inline]
RIP: 0010:__folio_remove_rmap mm/rmap.c:1663 [inline]
RIP: 0010:folio_remove_rmap_ptes+0x4d/0x7d0 mm/rmap.c:1779
Code: 00 fc ff df e8 94 35 b0 ff 4c 8d 6b 30 4c 89 e8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 75 05 00 00 45 0f b6 75 03 41 c1 e6 18 <bf> 00 00 00 f4 44 89 f6 e8 16 3a b0 ff 41 81 fe 00 00 00 f4 0f 84
RSP: 0018:ffffc900143a7650 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffea00020d5d80 RCX: ffff888024ce9e40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff9400041abb1 R12: ffff88804db51780
R13: ffffea00020d5db0 R14: 0000000000000000 R15: ffffea00020d5d80
FS:  0000000000000000(0000) GS:ffff888126cee000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2c50ea CR3: 000000000d3a8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 zap_present_folio_ptes mm/memory.c:1650 [inline]
 zap_present_ptes mm/memory.c:1708 [inline]
 do_zap_pte_range mm/memory.c:1810 [inline]
 zap_pte_range mm/memory.c:1854 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0x1aea/0x3ce0 mm/memory.c:2017
 unmap_single_vma mm/memory.c:2059 [inline]
 unmap_vmas+0x399/0x580 mm/memory.c:2101
 exit_mmap+0x239/0xb10 mm/mmap.c:1277
 __mmput+0xcb/0x3d0 kernel/fork.c:1173
 exit_mm+0x169/0x230 kernel/exit.c:581
 do_exit+0x627/0x22f0 kernel/exit.c:959
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1112
 __do_sys_exit_group kernel/exit.c:1123 [inline]
 __se_sys_exit_group kernel/exit.c:1121 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
 x64_sys_call+0x2210/0x2210 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa6b47bf749
Code: Unable to access opcode bytes at 0x7fa6b47bf71f.
RSP: 002b:00007fff36848f68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa6b47bf749
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fff36848fcc R08: 000000033684905f R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000102
R13: 00000000000927c0 R14: 00000000001262ea R15: 00007fff36849020
 </TASK>