INFO: task syz.4.1284:16871 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1284 state:D stack:25592 pid:16871 tgid:16870 ppid:9547 task_flags:0x400140 flags:0x00080003
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 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+0x1466/0x1b70 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:1759
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+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe51f4a0eea
RSP: 002b:00007fe51d705e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fe51d705ef0 RCX: 00007fe51f4a0eea
RDX: 0000200000000100 RSI: 0000200000000040 RDI: 00007fe51d705eb0
RBP: 0000200000000100 R08: 00007fe51d705ef0 R09: 0000000000800810
R10: 0000000000800810 R11: 0000000000000246 R12: 0000200000000040
R13: 00007fe51d705eb0 R14: 00000000000050f9 R15: 0000200000000340
INFO: task syz.5.1285:16873 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.1285 state:D stack:21432 pid:16873 tgid:16872 ppid:9701 task_flags:0x400140 flags:0x00080003
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 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+0x1466/0x1b70 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+0x2ab/0x680 fs/btrfs/disk-io.c:1980
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:1759
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+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b0e080eea
RSP: 002b:00007f2b0c2e5e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2b0c2e5ef0 RCX: 00007f2b0e080eea
RDX: 00002000000055c0 RSI: 0000200000000000 RDI: 00007f2b0c2e5eb0
RBP: 00002000000055c0 R08: 00007f2b0c2e5ef0 R09: 000000000300000a
R10: 000000000300000a R11: 0000000000000246 R12: 0000200000000000
R13: 00007f2b0c2e5eb0 R14: 00000000000055a3 R15: 0000200000000080
Showing all locks held in the system:
1 lock held by khungtaskd/38:
#0: ffffffff8d5aeba0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d5aeba0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8d5aeba0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5558:
#0: ffff88814e57d0a0 (&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+0x444/0x1400 drivers/tty/n_tty.c:2222
2 locks held by syz-executor/6881:
1 lock held by udevd/9863:
2 locks held by udevd/10033:
2 locks held by syz-executor/11377:
1 lock held by syz.4.1284/16871:
#0: ffff8880585a00d0 (&type->s_umount_key#65/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
1 lock held by syz.5.1285/16873:
#0: ffff888058b3c0d0 (&type->s_umount_key#65/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:344
3 locks held by syz.9.1430/18746:
3 locks held by syz.0.1434/18750:
2 locks held by syz.3.1431/18751:
1 lock held by udevadm/18752:
=============================================
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:
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:332 [inline]
watchdog+0xf3c/0xf80 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 18751 Comm: syz.3.1431 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__ref_is_percpu include/linux/percpu-refcount.h:174 [inline]
RIP: 0010:percpu_ref_tryget_many include/linux/percpu-refcount.h:243 [inline]
RIP: 0010:percpu_ref_tryget+0x8e/0x180 include/linux/percpu-refcount.h:266
Code: 45 f8 8a be 65 03 00 00 48 c7 c2 e0 45 f8 8a e8 58 b6 76 ff 49 bf 00 00 00 00 00 fc ff df 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 c8 b1 fb ff 49 8b 06 a8 03 75 6c 65 48 ff 00 40
RSP: 0018:ffffc9001fbd78a0 EFLAGS: 00000246
RAX: 1ffff1102808c362 RBX: ffffffff82265215 RCX: ce05827b6a61a400
RDX: 000000009f466dfb RSI: ffffffff8b3ecf40 RDI: ffffffff8b3ecf00
RBP: 1ffff11007283af6 R08: ffffffff82265215 R09: ffffffff8d5aeba0
R10: dffffc0000000000 R11: fffff94000319301 R12: ffff888140461b4c
R13: dffffc0000000000 R14: ffff888140461b10 R15: dffffc0000000000
FS: 00007f62124866c0(0000) GS:ffff888126d69000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563c85b18080 CR3: 000000005e7b2000 CR4: 00000000003526f0
Call Trace:
css_tryget include/linux/cgroup_refcnt.h:45 [inline]
get_mem_cgroup_from_mm+0x102/0x2e0 mm/memcontrol.c:940
__mem_cgroup_charge+0x15/0x80 mm/memcontrol.c:4709
mem_cgroup_charge include/linux/memcontrol.h:662 [inline]
shmem_alloc_and_add_folio mm/shmem.c:1922 [inline]
shmem_get_folio_gfp+0x74e/0x1a70 mm/shmem.c:2535
shmem_get_folio mm/shmem.c:2641 [inline]
shmem_write_begin+0xef/0x2a0 mm/shmem.c:3291
generic_perform_write+0x29d/0x8c0 mm/filemap.c:4300
shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3466
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+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f621421e1ff
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:00007f6212485df0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007f621421e1ff
RDX: 0000000001000000 RSI: 00007f620a066000 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000055a8
R10: 0000000000000002 R11: 0000000000000293 R12: 0000000000000004
R13: 00007f6212485ef0 R14: 00007f6212485eb0 R15: 00007f620a066000