INFO: task syz.6.857:14224 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.857 state:D stack:25624 pid:14224 tgid:14223 ppid:7061 task_flags:0x400140 flags:0x00080003
Call Trace:
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_init_workqueues+0x215/0x680 fs/btrfs/disk-io.c:1977
open_ctree+0x141d/0x3d20 fs/btrfs/disk-io.c:3410
btrfs_fill_super fs/btrfs/super.c:983 [inline]
btrfs_get_tree_super fs/btrfs/super.c:1946 [inline]
btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline]
btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123
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: 0033:0x7f4bb1fb0eea
RSP: 002b:00007f4bb0215e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4bb0215ef0 RCX: 00007f4bb1fb0eea
RDX: 0000200000005100 RSI: 0000200000000040 RDI: 00007f4bb0215eb0
RBP: 0000200000005100 R08: 00007f4bb0215ef0 R09: 0000000000800852
R10: 0000000000800852 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f4bb0215eb0 R14: 00000000000050f9 R15: 0000200000000100
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 kworker/u8:9/1226:
#0: ffff88813ff69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff88813ff69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc90004d97bc0 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc90004d97bc0 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
1 lock held by udevd/5165:
2 locks held by getty/5552:
#0: ffff8880348f10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e832e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x44f/0x1460 drivers/tty/n_tty.c:2211
2 locks held by udevd/5861:
5 locks held by kworker/u8:16/5997:
1 lock held by syz.6.857/14224:
#0: ffff88803079a0d0 (&type->s_umount_key#66/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
3 locks held by kworker/0:3/14765:
2 locks held by syz.7.1052/16383:
3 locks held by syz.5.1053/16385:
#0: ffff88802eeda0d0 (&type->s_umount_key#66/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
#1: ffffffff8db77418 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_super fs/btrfs/super.c:1928 [inline]
#1: ffffffff8db77418 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline]
#1: ffffffff8db77418 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x82b/0x1920 fs/btrfs/super.c:2123
#2: ffffffff8d67c6d8 (lock#3){+.+.}-{4:4}, at: __lru_add_drain_all+0x6b/0x5e0 mm/swap.c:840
3 locks held by syz.2.1054/16388:
4 locks held by syz.3.1051/16390:
=============================================
NMI backtrace for cpu 0
CPU: 0 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:
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
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 16383 Comm: syz.7.1052 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:182 [inline]
RIP: 0010:rt_mutex_slowunlock+0xb3/0x8a0 kernel/locking/rtmutex.c:1419
Code: f8 48 c1 e8 03 42 80 3c 20 00 74 05 e8 96 f4 4d f7 48 89 5c 24 68 48 c7 44 24 70 00 00 00 00 4c 89 ef e8 60 25 01 00 49 89 c6 <48> c7 c0 40 44 be 98 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 4f 06
RSP: 0018:ffffc90020daf7c0 EFLAGS: 00000046
RAX: 0000000000000246 RBX: ffffc90020daf820 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90020daf720
RBP: ffffc90020daf8c0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520041b5ee4 R12: dffffc0000000000
R13: ffff8880b8933c78 R14: 0000000000000246 R15: 1ffff920041b5f00
FS: 00007fa9f6cf66c0(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f71a9502a60 CR3: 00000000338ce000 CR4: 00000000003526f0
Call Trace:
spin_unlock include/linux/spinlock_rt.h:105 [inline]
__folio_batch_add_and_move+0x5da/0xa90 mm/swap.c:201
shmem_alloc_and_add_folio mm/shmem.c:1991 [inline]
shmem_get_folio_gfp+0xb56/0x1a70 mm/shmem.c:2556
shmem_get_folio mm/shmem.c:2662 [inline]
shmem_write_begin+0x166/0x320 mm/shmem.c:3315
generic_perform_write+0x29d/0x8c0 mm/filemap.c:4314
shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3490
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5d5/0xb40 fs/read_write.c:686
ksys_write+0x14b/0x260 fs/read_write.c:738
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: 0033:0x7fa9f8a8e1ff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007fa9f6cf5df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007fa9f8a8e1ff
RDX: 0000000001000000 RSI: 00007fa9ee8d6000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000005108
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000003
R13: 00007fa9f6cf5ef0 R14: 00007fa9f6cf5eb0 R15: 00007fa9ee8d6000