rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4294/1:b..l (detected by 1, t=10502 jiffies, g=9665, q=494) task:udevd state:R running task stack:24960 pid: 4294 ppid: 3544 flags:0x00004002 Call Trace: <TASK> context_switch kernel/sched/core.c:5027 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6549 preempt_schedule+0xd9/0xe0 kernel/sched/core.c:6574 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202 spin_unlock_irq include/linux/spinlock.h:413 [inline] loop_queue_work drivers/block/loop.c:1068 [inline] loop_queue_rq+0x9f7/0xae0 drivers/block/loop.c:2201 __blk_mq_issue_directly block/blk-mq.c:2008 [inline] __blk_mq_try_issue_directly+0x541/0x8b0 block/blk-mq.c:2064 blk_mq_request_issue_directly block/blk-mq.c:2112 [inline] blk_mq_try_issue_list_directly+0x245/0x650 block/blk-mq.c:2130 blk_mq_sched_insert_requests+0x284/0x570 block/blk-mq-sched.c:512 blk_mq_flush_plug_list+0x5de/0x6b0 block/blk-mq.c:1965 blk_flush_plug_list+0x44b/0x490 block/blk-core.c:1734 blk_finish_plug+0x59/0x80 block/blk-core.c:1751 read_pages+0x4cb/0x8e0 mm/readahead.c:150 page_cache_ra_unbounded+0x264/0x930 mm/readahead.c:211 do_page_cache_ra mm/readahead.c:269 [inline] force_page_cache_ra+0x378/0x3e0 mm/readahead.c:301 page_cache_sync_readahead include/linux/pagemap.h:833 [inline] filemap_get_pages mm/filemap.c:2551 [inline] filemap_read+0x71c/0x2980 mm/filemap.c:2634 blkdev_read_iter+0x12a/0x180 block/fops.c:560 call_read_iter include/linux/fs.h:2168 [inline] new_sync_read fs/read_write.c:404 [inline] vfs_read+0xa93/0xe10 fs/read_write.c:485 ksys_read+0x1a2/0x2c0 fs/read_write.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7ff59d1f3b6a RSP: 002b:00007ffc221b8298 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff59d1f3b6a RDX: 0000000000040000 RSI: 0000556b5973f1c8 RDI: 0000000000000009 RBP: 0000000000040000 R08: 0000556b5973f1a0 R09: 0000000000000008 R10: 0000000000004011 R11: 0000000000000246 R12: 0000556b5973f1a0 R13: 0000556b5973f1b8 R14: 0000556b5970faf8 R15: 0000556b5970faa0 </TASK> rcu: rcu_preempt kthread starved for 9859 jiffies! g9665 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:26816 pid: 15 ppid: 2 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:5027 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373 schedule+0x11b/0x1f0 kernel/sched/core.c:6456 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 </TASK> rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.171-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3932 [inline] rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619 update_process_times+0x196/0x200 kernel/time/timer.c:1818 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1688 [inline] __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1752 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x13b/0x4b0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline] RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline] RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:132 [inline] RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline] RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562 Code: a9 42 f7 48 83 e3 08 0f 85 0a 01 00 00 4c 8d 74 24 20 e8 34 24 49 f7 0f 1f 44 00 00 e8 da a5 42 f7 0f 00 2d 63 73 a5 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 cb 7d 8c f7 RSP: 0018:ffffc90000d67b00 EFLAGS: 000002d3 RAX: ffffffff8a3dcdd6 RBX: 0000000000000000 RCX: ffff888017df0000 RDX: 0000000000000000 RSI: ffffffff8a8b2a80 RDI: ffffffff8ad90500 RBP: ffffc90000d67b90 R08: ffffffff8186f230 R09: ffffed1002fbe001 R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920001acf60 R13: ffff888146803004 R14: ffffc90000d67b20 R15: dffffc0000000000 acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:697 cpuidle_enter_state+0x521/0xef0 drivers/cpuidle/cpuidle.c:237 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:351 call_cpuidle kernel/sched/idle.c:158 [inline] cpuidle_idle_call kernel/sched/idle.c:239 [inline] do_idle+0x3e4/0x670 kernel/sched/idle.c:306 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403 start_secondary+0x371/0x500 arch/x86/kernel/smpboot.c:281 secondary_startup_64_no_verify+0xb1/0xbb </TASK>