watchdog: BUG: soft lockup - CPU#0 stuck for 143s! [syz.0.5752:14379]
CPU#0 Utilization every 22s during lockup:
#1: 93% system, 4% softirq, 4% hardirq, 0% idle
#2: 93% system, 5% softirq, 4% hardirq, 0% idle
#3: 93% system, 4% softirq, 4% hardirq, 0% idle
#4: 93% system, 4% softirq, 4% hardirq, 0% idle
#5: 93% system, 4% softirq, 4% hardirq, 0% idle
Modules linked in:
CPU: 0 UID: 0 PID: 14379 Comm: syz.0.5752 Not tainted syzkaller #0 ecbc8af4db0b1e168e71992ad8df1de57efedc45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:430 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x7cb/0xe90 kernel/locking/qspinlock.c:508
Code: ff ff c6 44 16 06 02 66 c7 84 24 90 00 00 00 00 01 48 8b 44 24 48 0f b6 04 10 84 c0 75 5c 80 3f 00 74 0e c6 44 16 06 f8 f3 90 <41> ff c5 75 d3 eb 6d be 02 00 00 00 e8 04 66 3e fc 48 8d bc 24 90
RSP: 0018:ffffc900040f7900 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffffc900040f79a0 RCX: ffff888113a58000
RDX: dffffc0000000000 RSI: 1ffff9200081ef2c RDI: ffffffff8740d604
RBP: ffffc900040f7a10 R08: ffffffff8740d604 R09: 1ffffffff0e81ac0
R10: dffffc0000000000 R11: fffffbfff0e81ac1 R12: 0000000000000000
R13: 00000000ffff8577 R14: 1ffffffff0e81ac0 R15: 1ffffffff0e9cdf9
FS: 0000555594961500(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000117c08000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000006800 DR2: 0000000000009951
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock include/linux/spinlock.h:187 [inline]
__raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
_raw_spin_lock+0x115/0x120 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
write_seqlock include/linux/seqlock.h:876 [inline]
lock_mount_hash fs/namespace.c:225 [inline]
mntput_no_expire+0x157/0x6d0 fs/namespace.c:1421
mntput+0x63/0xd0 fs/namespace.c:1476
simple_release_fs+0xb4/0xe0 fs/libfs.c:1078
remove_one+0x368/0x3e0 fs/debugfs/inode.c:810
simple_recursive_removal+0x722/0x900 fs/libfs.c:623
debugfs_remove+0x5a/0x80 fs/debugfs/inode.c:832
ptp_release+0x97/0x250 drivers/ptp/ptp_chardev.c:150
posix_clock_release+0xb0/0x140 kernel/time/posix-clock.c:159
__fput+0x1fe/0xa00 fs/file_table.c:429
____fput+0x20/0x30 fs/file_table.c:457
task_work_run+0x1e5/0x260 kernel/task_work.c:246
resume_user_mode_work+0x35/0x50 include/linux/resume_user_mode.h:50
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x63/0xb0 kernel/entry/common.c:218
do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f7548d9bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc4c9e378 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffcc4c9e460 RCX: 00007f7548d9bf79
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000080e18 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2f720000 R11: 0000000000000246 R12: 00007ffcc4c9e4a0
R13: 00007f7549015fac R14: 00000000000813fc R15: 00007f7549015fa0
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 14391 Comm: syz.3.5756 Not tainted syzkaller #0 ecbc8af4db0b1e168e71992ad8df1de57efedc45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:next_peer fs/pnode.c:19 [inline]
RIP: 0010:do_make_slave fs/pnode.c:100 [inline]
RIP: 0010:change_mnt_propagation+0x112/0xb00 fs/pnode.c:128
Code: 24 20 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 17 11 e7 ff 4d 39 2e 0f 84 8f 00 00 00 <49> 81 c4 d8 00 00 00 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc
RSP: 0018:ffffc90003e079c0 EFLAGS: 00000283
RAX: 1ffff11022c988ac RBX: ffffffffffffff28 RCX: dffffc0000000000
RDX: ffffc90006e47000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc90003e07a10 R08: ffff88814ef6a66f R09: 0000000000000000
R10: ffff88814ef6a660 R11: ffffed1029ded4ce R12: ffff8881164c4540
R13: ffff888110fd7660 R14: ffff8881164c4560 R15: ffff888129242c40
FS: 00007fb3030676c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9c73d7fff8 CR3: 0000000152f54000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000006800 DR2: 0000000000009951
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
umount_tree+0xe16/0xf90 fs/namespace.c:1813
attach_recursive_mnt+0x6e7/0x2210 fs/namespace.c:2569
graft_tree+0x157/0x1c0 fs/namespace.c:2704
do_loopback+0x36a/0x4c0 fs/namespace.c:2836
path_mount+0x56b/0x1010 fs/namespace.c:3878
do_mount fs/namespace.c:3897 [inline]
__do_sys_mount fs/namespace.c:4107 [inline]
__se_sys_mount+0x2bf/0x480 fs/namespace.c:4084
__x64_sys_mount+0xc3/0xf0 fs/namespace.c:4084
x64_sys_call+0x2021/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fb30219bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb303067028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb302416090 RCX: 00007fb30219bf79
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000200000000000
RBP: 00007fb3022327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000803400 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb302416128 R14: 00007fb302416090 R15: 00007ffc9d32acd8
</TASK>