rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5856/1:b..l P5200/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=14081, q=451 ncpus=2)
task:udevd state:R running task stack:25432 pid:5200 tgid:5200 ppid:1 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7193
irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:114 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:128 [inline]
RIP: 0010:lock_acquire+0xd1/0x340 kernel/locking/lockdep.c:5864
Code: 9f 92 83 b8 2c 0b 00 00 00 0f 85 d5 00 00 00 48 c7 44 24 30 00 00 00 00 9c 8f 44 24 30 4c 89 74 24 10 4d 89 fe 4c 8b 7c 24 30 48 c7 c7 0e cb 9a 8d e8 32 61 bf 09 65 ff 05 5b 87 01 11 45 31
RSP: 0018:ffffc900030a7258 EFLAGS: 00000246
RAX: ffff888053f23d00 RBX: 0000000000000000 RCX: a9e718f69e2def00
RDX: 0000000000000000 RSI: ffffffff81742fa2 RDI: 1ffffffff1c27e5c
RBP: ffffffff81742f85 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc900030a7418 R11: ffffffff81ad9d50 R12: 0000000000000002
R13: ffffffff8e13f2e0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock include/linux/rcupdate.h:867 [inline]
class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
unwind_next_frame+0xc2/0x23d0 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5267 [inline]
kmem_cache_alloc_lru_noprof+0x36c/0x6e0 mm/slub.c:5286
__d_alloc+0x37/0x6f0 fs/dcache.c:1730
d_alloc_parallel+0xe1/0x1610 fs/dcache.c:2594
__lookup_slow+0x116/0x3d0 fs/namei.c:1843
lookup_slow+0x53/0x70 fs/namei.c:1875
walk_component fs/namei.c:2221 [inline]
lookup_last fs/namei.c:2722 [inline]
path_lookupat+0x3f5/0x8c0 fs/namei.c:2746
filename_lookup+0x212/0x570 fs/namei.c:2775
do_readlinkat+0xd9/0x500 fs/stat.c:576
__do_sys_readlink fs/stat.c:613 [inline]
__se_sys_readlink fs/stat.c:610 [inline]
__x64_sys_readlink+0x7f/0x90 fs/stat.c:610
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: 0033:0x7f31d31153a7
RSP: 002b:00007ffe7997c478 EFLAGS: 00000206 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffe7997c680 RCX: 00007f31d31153a7
RDX: 0000000000000200 RSI: 00007ffe7997c480 RDI: 00007ffe7997c680
RBP: 0000559b211dc910 R08: 0000000000000064 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffe7997c480
R13: 0000559b01d9e100 R14: 0000000000000001 R15: 00007ffe7997cca0
task:udevd state:R running task stack:24376 pid:5856 tgid:5856 ppid:5200 task_flags:0x400140 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7193
irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x16c/0x340 kernel/locking/lockdep.c:5872
Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 44 41 01 11 <48> 3b 44 24 58 0f 85 e5 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90003fef7f8 EFLAGS: 00000206
RAX: 7fb76eaddfaf8500 RBX: 0000000000000000 RCX: 7fb76eaddfaf8500
RDX: 000000005a44979c RSI: ffffffff8db7ed49 RDI: ffffffff8be07960
RBP: ffffffff81742f85 R08: ffffffff81742f85 R09: ffffffff8e13f2e0
R10: ffffc90003fefa18 R11: fffff520007fdf45 R12: 0000000000000002
R13: ffffffff8e13f2e0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock include/linux/rcupdate.h:867 [inline]
class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
unwind_next_frame+0xc2/0x23d0 arch/x86/kernel/unwind_orc.c:495
__unwind_start+0x5b9/0x760 arch/x86/kernel/unwind_orc.c:773
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xe4/0x150 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6674 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6785
do_symlinkat+0x3be/0x420 fs/namei.c:5621
__do_sys_symlink fs/namei.c:5633 [inline]
__se_sys_symlink fs/namei.c:5631 [inline]
__x64_sys_symlink+0x7a/0x90 fs/namei.c:5631
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: 0033:0x7f31d3115527
RSP: 002b:00007ffe7997c4b8 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000559b211f1830 RCX: 00007f31d3115527
RDX: fffffffffffffe68 RSI: 00007ffe7997c4c0 RDI: 0000559b211fccb0
RBP: 0000000000000054 R08: 0000000000000064 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffe7997c4c0
R13: 0000559b211ea190 R14: 0000000000000008 R15: 0000559b211f1830
rcu: rcu_preempt kthread starved for 10452 jiffies! g14081 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:27168 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5258 [inline]
__schedule+0x150e/0x5070 kernel/sched/core.c:6866
__schedule_loop kernel/sched/core.c:6948 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6963
schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
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
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 6090 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 1a 4e 3e f6 48 89 df e8 52 c5 3e f6 e8 4d 43 69 f6 fb bf 01 00 00 00 82 ba 30 f6 65 8b 05 db 5f 3f 07 85 c0 74 07 5b e9 c1 4b 00 00
RSP: 0018:ffffc900035b7c60 EFLAGS: 00000286
RAX: 09142d9ccebc1500 RBX: ffff888026450940 RCX: 09142d9ccebc1500
RDX: 0000000000000000 RSI: ffffffff8d997e54 RDI: 0000000000000001
RBP: 0000000000000011 R08: ffffffff8fa22f77 R09: 1ffffffff1f445ee
R10: dffffc0000000000 R11: fffffbfff1f445ef R12: 1ffff11004c8a17b
R13: 0000000000000000 R14: 0000000004000000 R15: ffff888026450bd8
FS: 0000555556364500(0000) GS:ffff888125c25000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5744bb74e0 CR3: 0000000053c42000 CR4: 00000000003526f0
Call Trace:
spin_unlock_irq include/linux/spinlock.h:401 [inline]
get_signal+0x11a7/0x1340 kernel/signal.c:3037
arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2d0/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f72cf584d97
Code: 24 08 64 48 2b 14 25 28 00 00 00 75 05 48 83 c4 18 c3 e8 2c dc 00 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8b 05 71 e9 22 00 <48> 85 c0 74 14 48 83 ec 08 ff d0 85 c0 75 1a 31 c0 48 83 c4 08 c3
RSP: 002b:00007ffe662f6098 EFLAGS: 00000206
RAX: 00007f72d0364a90 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00007f72cf69e120 RSI: 00007ffe662f60f0 RDI: 0000000000000001
RBP: 00007f72cf62d196 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f72cf7e5fa0 R14: 00007f72cf7e5fa0 R15: 0000000000000004