rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=411/1/0x4000000000000000 softirq=8715/8716 fqs=254 (detected by 1, t=10502 jiffies, g=10277, q=13131) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 1182 Comm: kworker/u4:3 Not tainted 5.15.186-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: writeback wb_workfn (flush-8:0) RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:768 [inline] RIP: 0010:advance_sched+0x760/0x940 net/sched/sch_taprio.c:771 Code: 00 00 48 c7 c2 20 38 02 8b e8 bc 49 95 01 4c 89 f7 e8 e4 7d cc ff e8 2f f7 9f 01 89 c3 31 ff 89 c6 e8 84 1a 76 f9 85 db 74 10 ab f0 61 f9 84 c0 74 0e e8 12 17 76 f9 eb 56 e8 0b 17 76 f9 eb RSP: 0018:ffffc90000007c80 EFLAGS: 00000002 RAX: ffffffff8801abec RBX: 0000000000000001 RCX: ffff8880226a8000 RDX: 0000000000010000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffff88801db7cb60 R08: dffffc0000000000 R09: ffffed1003b6f932 R10: ffffed1003b6f932 R11: 1ffff11003b6f931 R12: ffff88801db7cae8 R13: dffffc0000000000 R14: ffff88801db7c800 R15: 184dbd672545c90f FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055ecd7e5b4a8 CR3: 00000000586b4000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1690 [inline] __hrtimer_run_queues+0x53d/0xc40 kernel/time/hrtimer.c:1754 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 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 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:202 Code: 66 2e 0f 1f 84 00 00 00 00 00 53 48 89 fb e8 17 00 00 00 48 8b 3d 50 eb f0 0b 48 89 de 5b e9 37 af 44 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d a4 ac 8a 7e 65 8b 15 a5 ac 8a 7e 81 e2 00 RSP: 0018:ffffc900053b63f0 EFLAGS: 00000282 RAX: 000000000004001a RBX: ffff888023892c48 RCX: ffff8880226a8000 RDX: 0000000000000000 RSI: ffff888023892c00 RDI: ffff888021c78000 RBP: dffffc0000000000 R08: ffff8880226a8000 R09: 0000000000000003 R10: 000000000000000d R11: 0000000000000000 R12: ffff888021c78000 R13: dffffc0000000000 R14: ffff888023892c00 R15: ffff888021c78000 elv_rqhash_add+0x23/0x1f0 block/elevator.c:214 dd_insert_request block/mq-deadline.c:755 [inline] dd_insert_requests+0xa63/0xdb0 block/mq-deadline.c:783 blk_mq_sched_insert_requests+0x276/0x5c0 block/blk-mq-sched.c:504 blk_mq_flush_plug_list+0x57f/0x660 block/blk-mq.c:1971 blk_flush_plug_list+0x3ec/0x430 block/blk-core.c:1734 blk_schedule_flush_plug include/linux/blkdev.h:1235 [inline] io_schedule_prepare kernel/sched/core.c:8452 [inline] io_schedule+0x74/0xd0 kernel/sched/core.c:8483 rq_qos_wait+0x1f5/0x2a0 block/blk-rq-qos.c:288 __wbt_wait block/blk-wbt.c:522 [inline] wbt_wait+0x37b/0x660 block/blk-wbt.c:586 __rq_qos_throttle+0x61/0xa0 block/blk-rq-qos.c:72 rq_qos_throttle block/blk-rq-qos.h:203 [inline] blk_mq_submit_bio+0x3fe/0x17b0 block/blk-mq.c:2232 __submit_bio+0x7bd/0x810 block/blk-core.c:917 __submit_bio_noacct_mq block/blk-core.c:997 [inline] submit_bio_noacct+0x5f1/0x6d0 block/blk-core.c:1027 submit_bio+0x2be/0x560 block/blk-core.c:1089 ext4_io_submit+0x14a/0x200 fs/ext4/page-io.c:381 ext4_writepages+0xf7c/0x2d20 fs/ext4/inode.c:2849 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1647 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1930 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2001 wb_writeback+0x455/0xb90 fs/fs-writeback.c:2106 wb_check_old_data_flush fs/fs-writeback.c:2206 [inline] wb_do_writeback fs/fs-writeback.c:2259 [inline] wb_workfn+0xaaa/0xe60 fs/fs-writeback.c:2288 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: rcu_preempt kthread starved for 9987 jiffies! g10277 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:27496 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5030 [inline] __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376 schedule+0x11b/0x1e0 kernel/sched/core.c:6459 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 3508 Comm: jbd2/sda1-8 Not tainted 5.15.186-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x10c8/0x1220 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+0x831/0x1110 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:1818 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1690 [inline] __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 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 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] RIP: 0010:kvm_wait+0x141/0x190 arch/x86/kernel/kvm.c:918 Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 47 0f b6 1f e8 4f e9 49 00 44 38 e3 75 10 66 90 0f 00 2d 21 6f d4 08 fb f4 33 ff ff ff fb e9 2d ff ff ff e8 5f a5 6d 08 89 f9 80 e1 07 38 RSP: 0018:ffffc9000e4d70c0 EFLAGS: 00000246 RAX: fbb802c90253c000 RBX: 0000000000000003 RCX: fbb802c90253c000 RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: ffffffff8a59a900 RBP: ffffc9000e4d7170 R08: dffffc0000000000 R09: fffffbfff1ff3624 R10: fffffbfff1ff3624 R11: 1ffffffff1ff3623 R12: 0000000000000003 R13: ffff8880b913b114 R14: dffffc0000000000 R15: 1ffff92001c9ae18 pv_wait arch/x86/include/asm/paravirt.h:597 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x60f/0x9c0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115 spin_lock include/linux/spinlock.h:363 [inline] dd_bio_merge+0xc4/0x150 block/mq-deadline.c:704 blk_mq_sched_bio_merge block/blk-mq-sched.h:40 [inline] blk_mq_submit_bio+0xa03/0x17b0 block/blk-mq.c:2229 __submit_bio+0x7bd/0x810 block/blk-core.c:917 __submit_bio_noacct_mq block/blk-core.c:997 [inline] submit_bio_noacct+0x5f1/0x6d0 block/blk-core.c:1027 submit_bio+0x2be/0x560 block/blk-core.c:1089 submit_bh+0x23/0x30 fs/buffer.c:3062 jbd2_journal_commit_transaction+0x253f/0x5db0 fs/jbd2/commit.c:765 kjournald2+0x460/0x8f0 fs/jbd2/journal.c:213 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287