rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4977/1:b..l P6399/1:b..l
rcu: (detected by 1, t=10502 jiffies, g=20153, q=524 ncpus=2)
task:sed state:R running task stack:25112 pid:6399 tgid:6399 ppid:6396 task_flags:0x400000 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x10e9/0x6820 kernel/sched/core.c:7188
preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7512
irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline]
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__legitimize_mnt+0x0/0x1b0 fs/namespace.c:741
Code: 4c 89 ff e8 12 c7 e1 ff e9 3b fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <0f> 1f 40 d6 41 55 41 54 55 89 f5 53 48 89 fb e8 bc 0d 74 ff 44 8b
RSP: 0018:ffffc90003b8f9c0 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc90003b8fc00 RCX: ffffffff828cd89c
RDX: 1ffff92000771f80 RSI: 000000000000328e RDI: ffff88801ced18a0
RBP: 000000000000328e R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000002
R13: ffffc90003b8fc40 R14: ffff8880249dd608 R15: 0000000000000000
__legitimize_path+0x38/0x1d0 fs/namei.c:862
legitimize_path fs/namei.c:879 [inline]
try_to_unlazy+0x147/0x910 fs/namei.c:943
complete_walk+0x125/0x340 fs/namei.c:1059
do_open fs/namei.c:4665 [inline]
path_openat+0x11cb/0x31a0 fs/namei.c:4858
do_file_open+0x20e/0x430 fs/namei.c:4887
do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
do_sys_open fs/open.c:1370 [inline]
__do_sys_openat fs/open.c:1386 [inline]
__se_sys_openat fs/open.c:1381 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1381
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6f452de0ba
RSP: 002b:00007ffd40be4078 EFLAGS: 00000206 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ffd40be40f0 RCX: 00007f6f452de0ba
RDX: 0000000000080000 RSI: 00007ffd40be40f0 RDI: 00000000ffffff9c
RBP: 00007ffd40be40e0 R08: 00007ffd40be42e7 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 000000000000001b
R13: 00007f6f452b2050 R14: 00007ffd40be4300 R15: 0000000000000000
task:udevd state:R running task stack:24792 pid:4977 tgid:4977 ppid:1 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x10e9/0x6820 kernel/sched/core.c:7188
preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7512
irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:476 [inline]
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
irqentry_exit+0x1fe/0x790 kernel/entry/common.c:164
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x19e/0x310 kernel/locking/lockdep.c:5893
Code: ff 65 0f c1 05 9b 3e 26 12 83 f8 01 0f 85 28 01 00 00 9c 58 f6 c4 02 0f 85 13 01 00 00 41 f7 c6 00 02 00 00 0f 85 c0 00 00 00 <48> 8b 44 24 10 65 48 2b 05 ed f6 25 12 0f 85 4e 01 00 00 48 83 c4
RSP: 0018:ffffc900039078a8 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e7e54e0 RCX: ffffc900039078b4
RDX: 0000000000000001 RSI: ffffffff8def8e2a RDI: ffffffff8c1c3200
RBP: ffffffff81b7c1ae R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000017658 R12: ffff88807a864a00
R13: ffffc90003907960 R14: 0000000000000202 R15: 0000000000000002
rcu_lock_release include/linux/rcupdate.h:310 [inline]
rcu_read_unlock include/linux/rcupdate.h:869 [inline]
class_rcu_destructor include/linux/rcupdate.h:1181 [inline]
unwind_next_frame+0x3c3/0x2090 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
save_stack+0x162/0x1e0 mm/page_owner.c:165
__reset_page_owner+0x84/0x190 mm/page_owner.c:320
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1402 [inline]
__free_frozen_pages+0x747/0x1040 mm/page_alloc.c:2943
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4569 [inline]
slab_alloc_node mm/slub.c:4898 [inline]
kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905
alloc_filename fs/namei.c:142 [inline]
do_getname+0x35/0x390 fs/namei.c:182
getname include/linux/fs.h:2526 [inline]
class_filename_constructor include/linux/fs.h:2553 [inline]
do_sys_openat2+0xc5/0x1e0 fs/open.c:1363
do_sys_open fs/open.c:1370 [inline]
__do_sys_openat fs/open.c:1386 [inline]
__se_sys_openat fs/open.c:1381 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1381
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7e370a7407
RSP: 002b:00007ffca54d6970 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7e37795880 RCX: 00007f7e370a7407
RDX: 0000000000080141 RSI: 000055b07069702e RDI: ffffffffffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001a4 R11: 0000000000000202 R12: 00000000ffffffff
R13: 00000000ffffffff R14: ffffffffffffffff R15: 00007ffca54d6c90
rcu: rcu_preempt kthread starved for 10507 jiffies! g20153 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:28216 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5387 [inline]
__schedule+0x10e9/0x6820 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7282
schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 6404 Comm: vhost-6402 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 66 e6 57 f6 48 89 df e8 3e 36 58 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 a5 09 48 f6 65 8b 05 fe de 7d 08 85 c0 74 16 5b
RSP: 0018:ffffc90003bbfb48 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffff8880523a2b08 RCX: 0000000000000040
RDX: 0000000000000000 RSI: ffffffff8df1e362 RDI: ffffffff8c1c3200
RBP: 0000000000000293 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880523a2b48
R13: 0000000000000293 R14: ffff8880523a2b08 R15: ffff88802a32cff0
FS: 00007fa132cce6c0(0000) GS:ffff888124479000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000002eca6000 CR4: 00000000003526f0
Call Trace:
spin_unlock_irqrestore include/linux/spinlock.h:408 [inline]
eventfd_signal_mask+0x175/0x1d0 fs/eventfd.c:78
eventfd_signal include/linux/eventfd.h:89 [inline]
vhost_update_used_flags+0x36b/0x400 drivers/vhost/vhost.c:2580
vhost_disable_notify+0xbe/0x1b0 drivers/vhost/vhost.c:3258
vhost_vsock_handle_tx_kick+0x18e/0xdc0 drivers/vhost/vsock.c:526
vhost_run_work_list+0x183/0x220 drivers/vhost/vhost.c:454
vhost_task_fn+0x156/0x430 kernel/vhost_task.c:49
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245