rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3935/1:b..l (detected by 1, t=10502 jiffies, g=3457, q=405 ncpus=2) task:udevd state:R running task stack:0 pid:3935 ppid:1 flags:0x00000004 Call trace: __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555 context_switch kernel/sched/core.c:5245 [inline] __schedule+0xdd0/0x1b0c kernel/sched/core.c:6562 preempt_schedule_irq+0x8c/0x1ac kernel/sched/core.c:6874 arm64_preempt_schedule_irq+0x44/0x54 arch/arm64/kernel/entry-common.c:265 __el1_irq arch/arm64/kernel/entry-common.c:474 [inline] el1_interrupt+0x3c/0x54 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] lock_acquire+0x24c/0x63c kernel/locking/lockdep.c:5665 rcu_lock_acquire+0x44/0x54 include/linux/rcupdate.h:350 rcu_read_lock include/linux/rcupdate.h:791 [inline] page_ext_get+0x2c/0x2c4 mm/page_ext.c:157 __page_table_check_zero+0xf4/0x2b0 mm/page_table_check.c:146 page_table_check_free include/linux/page_table_check.h:46 [inline] free_pages_prepare mm/page_alloc.c:1487 [inline] free_pcp_prepare mm/page_alloc.c:1536 [inline] free_unref_page_prepare+0x9e4/0xaf0 mm/page_alloc.c:3413 free_unref_page+0x7c/0x3a0 mm/page_alloc.c:3508 free_the_page mm/page_alloc.c:781 [inline] __free_pages+0x1a0/0x1cc mm/page_alloc.c:5746 __free_slab+0x104/0x294 mm/slub.c:2021 free_slab mm/slub.c:2036 [inline] discard_slab+0x58/0xd4 mm/slub.c:2042 __unfreeze_partials+0x150/0x190 mm/slub.c:2591 put_cpu_partial+0x18c/0x1f8 mm/slub.c:2667 __slab_free+0x1a4/0x268 mm/slub.c:3564 do_slab_free mm/slub.c:3641 [inline] ___cache_free+0x168/0x198 mm/slub.c:3694 qlink_free+0x5c/0xa0 mm/kasan/quarantine.c:168 qlist_free_all+0x3c/0xcc mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x124/0x130 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x2c/0x88 mm/kasan/common.c:306 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x74/0x430 mm/slab.h:737 slab_alloc_node mm/slub.c:3359 [inline] slab_alloc mm/slub.c:3367 [inline] __kmem_cache_alloc_lru mm/slub.c:3374 [inline] kmem_cache_alloc+0x22c/0x308 mm/slub.c:3383 getname_flags+0xb8/0x45c fs/namei.c:139 getname fs/namei.c:218 [inline] __do_sys_unlinkat fs/namei.c:-1 [inline] __se_sys_unlinkat fs/namei.c:4434 [inline] __arm64_sys_unlinkat+0xb4/0xfc fs/namei.c:4434 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g3457 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=1166 rcu: rcu_preempt kthread starved for 10502 jiffies! g3457 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:0 pid:16 ppid:2 flags:0x00000008 Call trace: __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555 context_switch kernel/sched/core.c:5245 [inline] __schedule+0xdd0/0x1b0c kernel/sched/core.c:6562 schedule+0xc4/0x170 kernel/sched/core.c:6638 schedule_timeout+0x194/0x2f4 kernel/time/timer.c:2168 rcu_gp_fqs_loop+0x2b4/0x1378 kernel/rcu/tree.c:1706 rcu_gp_kthread+0xb4/0x2fc kernel/rcu/tree.c:1905 kthread+0x250/0x2d8 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 rcu: Stack dump where RCU GP kthread last ran: Task dump for CPU 0: task:syz.1.23 state:R running task stack:0 pid:4504 ppid:4439 flags:0x00000000 Call trace: __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555 0xffff800008000000