rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P31499/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=172721, q=496 ncpus=2)
task:udevd state:R running task stack:25896 pid:31499 tgid:31499 ppid:5184 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190
irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x183/0x2d0 kernel/locking/lockdep.c:5893
Code: 0f c1 05 58 e3 17 12 83 f8 01 0f 85 03 01 00 00 9c 58 f6 c4 02 0f 85 ee 00 00 00 41 f7 c5 00 02 00 00 74 01 fb 48 8b 44 24 10 <65> 48 2b 05 ed 9b 17 12 0f 85 32 01 00 00 48 83 c4 18 5b 41 5c 41
RSP: 0018:ffffc9000b8c7958 EFLAGS: 00000206
RAX: bc777318fd381000 RBX: ffffffff8e3c9620 RCX: ffffc9000b8c7964
RDX: 0000000000000000 RSI: ffffffff8da9cb15 RDI: ffffffff8bf24880
RBP: 0000000000000001 R08: ffffffff912f04e4 R09: 00000000ffffffff
R10: 0000000000000002 R11: 00000000000128b0 R12: ffffffff816cb9a4
R13: 0000000000000206 R14: ffff88802eada4c0 R15: 0000000000000001
rcu_lock_release include/linux/rcupdate.h:341 [inline]
rcu_read_unlock include/linux/rcupdate.h:897 [inline]
class_rcu_destructor include/linux/rcupdate.h:1195 [inline]
unwind_next_frame+0x3f9/0x20a0 arch/x86/kernel/unwind_orc.c:479
arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
kasan_save_track+0x14/0x30 mm/kasan/common.c:77
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6663 [inline]
kmem_cache_free+0x2d8/0x770 mm/slub.c:6774
putname+0xf5/0x1a0 fs/namei.c:297
do_readlinkat+0x1d4/0x3a0 fs/stat.c:596
__do_sys_readlink fs/stat.c:613 [inline]
__se_sys_readlink fs/stat.c:610 [inline]
__x64_sys_readlink+0x78/0xc0 fs/stat.c:610
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe18ab153a7
RSP: 002b:00007ffd01bf1c98 EFLAGS: 00000206 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffd01bf24e0 RCX: 00007fe18ab153a7
RDX: 0000000000000400 RSI: 00007ffd01bf20a0 RDI: 00007ffd01bf1ca0
RBP: 0000000000000200 R08: 000055edcfea5c29 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffd01bf1ca0
R13: 00007ffd01bf20a0 R14: 000055edcfea8ca4 R15: 000055edcfea8bcc
rcu: rcu_preempt kthread starved for 10533 jiffies! g172721 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:28176 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1139/0x6150 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6960
schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 379 Comm: vhost-378 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:hlock_class kernel/locking/lockdep.c:234 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4854 [inline]
RIP: 0010:__lock_acquire+0x204/0x2890 kernel/locking/lockdep.c:5187
Code: 00 00 c1 e2 15 09 d0 41 8b 56 20 81 e2 ff 1f 00 00 09 d0 41 89 46 20 8b 84 24 c0 00 00 00 41 89 46 24 4c 89 c8 25 ff 1f 00 00 <48> 0f a3 05 64 9c 1e 14 0f 83 db 05 00 00 48 8d 04 80 48 8d 04 80
RSP: 0018:ffffc90004e4fbb0 EFLAGS: 00000006
RAX: 0000000000000435 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000435 RSI: 0000000000000000 RDI: ffffffff8e448db8
RBP: 0000000000000001 R08: 0000000000080000 R09: 0000000000000435
R10: 0000000000000000 R11: ffff88804dc2aff0 R12: ffff88804dc2a4c0
R13: ffffffff8e448db8 R14: ffff88804dc2b018 R15: 0000000000000001
FS: 00007f7df14326c0(0000) GS:ffff888124907000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3639db CR3: 0000000073a80000 CR4: 00000000003526f0
Call Trace:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
kcov_remote_start+0x15c/0x680 kernel/kcov.c:886
kcov_remote_start_common include/linux/kcov.h:50 [inline]
vhost_run_work_list+0x16d/0x230 drivers/vhost/vhost.c:453
vhost_task_fn+0x165/0x460 kernel/vhost_task.c:49
ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246