rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5917/1:b..l rcu: (detected by 0, t=10502 jiffies, g=8845, q=545 ncpus=2) task:udevd state:R running task stack:27672 pid:5917 tgid:5917 ppid:5180 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6911 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x5e/0x380 kernel/locking/lockdep.c:5872 Code: 05 bb 36 29 12 83 f8 07 0f 87 f0 00 00 00 48 0f a3 05 86 b9 f4 0e 0f 82 c2 02 00 00 8b 35 6e ed f4 0e 85 f6 0f 85 dd 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d 36 29 12 0f 85 02 03 00 00 48 83 c4 RSP: 0018:ffffc90003ef7378 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff8de53b7a RDI: ffffffff8c1b1920 RBP: ffffffff8e7e7920 R08: 00000000d1f694f0 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0xd1/0x1ea0 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 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4873 kmem_alloc_batch+0x49/0x170 lib/debugobjects.c:371 fill_pool lib/debugobjects.c:420 [inline] debug_objects_fill_pool lib/debugobjects.c:742 [inline] debug_objects_fill_pool+0x352/0x700 lib/debugobjects.c:714 debug_object_activate+0x103/0x490 lib/debugobjects.c:831 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline] __call_rcu_common.constprop.0+0x35/0x9b0 kernel/rcu/tree.c:3116 slab_free_hook mm/slub.c:2649 [inline] slab_free mm/slub.c:6165 [inline] kmem_cache_free+0x44b/0x6a0 mm/slub.c:6295 tear_down_vmas+0x2a5/0x600 mm/mmap.c:1264 exit_mmap+0x469/0xa30 mm/mmap.c:1322 __mmput+0x12a/0x410 kernel/fork.c:1175 mmput+0x67/0x80 kernel/fork.c:1198 exit_mm kernel/exit.c:581 [inline] do_exit+0x819/0x2b60 kernel/exit.c:964 do_group_exit+0xd5/0x2a0 kernel/exit.c:1118 __do_sys_exit_group kernel/exit.c:1129 [inline] __se_sys_exit_group kernel/exit.c:1127 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1127 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9bca0f16c5 RSP: 002b:00007ffc047d39d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 000055ff7f502070 RCX: 00007f9bca0f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 000055ff7f2ae2c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc047d3a20 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10453 jiffies! g8845 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:27032 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7008 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+0x754/0xd80 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: 0 UID: 0 PID: 5921 Comm: syz-executor288 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 90 f3 0f 1e fa 53 48 8b 74 24 08 48 89 fb 48 83 c7 18 e8 7a 3d 51 f6 48 89 df e8 62 8d 51 f6 e8 ad 25 7d f6 fb bf 01 00 00 00 22 ae 41 f6 65 8b 05 cb 6e 7a 08 85 c0 74 06 5b c3 cc cc cc cc RSP: 0018:ffffc9000456fc98 EFLAGS: 00000202 RAX: 0000000008f2016d RBX: ffff888028d82e40 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8de79cf2 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000021 R13: ffff888028d83240 R14: dffffc0000000000 R15: ffff888027778000 FS: 000055556d1b9400(0000) GS:ffff88812433c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4cd68ee000 CR3: 0000000029105000 CR4: 00000000003526f0 Call Trace: spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x195a/0x21e0 kernel/signal.c:3037 arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98 __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 include/linux/entry-common.h:325 [inline] do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4cd69281b9 Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcfd593c08 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f4cd69281b9 RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f4cd699628e R09: 00007f4cd699628e R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcfd593c2c R13: 00007ffcfd593c60 R14: 00007ffcfd593c40 R15: 0000000000000004 sched: DL replenish lagged too much