rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=15589, q=260 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10499 (4294965487-4294954988), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10499 jiffies! g15589 f0x2 RCU_GP_CLEANUP(7) ->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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x168f/0x4c70 kernel/sched/core.c:6767 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6947 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6971 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irq+0x45/0x50 kernel/locking/spinlock.c:202 rcu_gp_cleanup+0x4f2/0xfb0 kernel/rcu/tree.c:2161 rcu_gp_kthread+0xa7/0x390 kernel/rcu/tree.c:2252 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6820 Comm: syz.1.264 Not tainted 6.15.0-rc6-syzkaller-00025-g627277ba7c23 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:65 Code: 16 9c e3 f5 eb a7 e8 8f e3 ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 89 fe 48 c7 c7 e0 04 c1 8b e9 bd fe ff ff cc cc cc RSP: 0018:ffffc90000007250 EFLAGS: 00000006 RAX: 0000000000000000 RBX: 0000000000000006 RCX: 93edd1a766e6de00 RDX: 0000000000010100 RSI: ffffffff8bc104c0 RDI: ffffffff8d74bc97 RBP: ffff88806a628d50 R08: ffff88806a628c87 R09: 1ffff1100d4c5190 R10: dffffc0000000000 R11: ffffed100d4c5191 R12: ffff88805ab64340 R13: ffffffff8970ae9f R14: ffff88805ab64300 R15: ffff888032738000 FS: 00007f9371dd46c0(0000) GS:ffff8881260fb000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fcfc000 CR3: 000000007cd54000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lockdep_recursion_inc kernel/locking/lockdep.c:467 [inline] lock_release+0xbc/0x3e0 kernel/locking/lockdep.c:5886 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline] _raw_spin_unlock+0x16/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] advance_sched+0x99f/0xc90 net/sched/sch_taprio.c:981 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x529/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:debug_lockdep_rcu_enabled+0x6/0x40 kernel/rcu/update.c:320 Code: 0b 90 90 90 eb c4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 31 c0 <83> 3d 27 a5 2e 04 00 74 1e 83 3d ea d2 2e 04 00 74 15 65 48 8b 0c RSP: 0018:ffffc90000007710 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff821fb886 RCX: 93edd1a766e6de00 RDX: 0000000000000000 RSI: ffffffff8d9226df RDI: ffffffff8bc104e0 RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8171ca05 R12: 1ffff92000000efd R13: ffffc90000007820 R14: ffffc900000077e8 R15: ffffffff8171ca05 rcu_read_lock include/linux/rcupdate.h:842 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xcb/0x2390 arch/x86/kernel/unwind_orc.c:479 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:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2380 [inline] slab_free mm/slub.c:4642 [inline] kmem_cache_free+0x192/0x3f0 mm/slub.c:4744 rcu_do_batch kernel/rcu/tree.c:2568 [inline] rcu_core+0xca8/0x1710 kernel/rcu/tree.c:2824 handle_softirqs+0x286/0x870 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline] sysvec_call_function_single+0xa3/0xc0 arch/x86/kernel/smp.c:266 asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:709 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194 Code: 74 05 e8 8b c3 75 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 83 46 3f f6 65 8b 05 cc a5 20 07 85 c0 74 40 48 c7 04 24 0e 36 RSP: 0018:ffffc9000dd9fb80 EFLAGS: 00000206 RAX: 93edd1a766e6de00 RBX: 0000000000000a02 RCX: 93edd1a766e6de00 RDX: 0000000000000007 RSI: ffffffff8d7387c2 RDI: 0000000000000001 RBP: ffffc9000dd9fc10 R08: ffffffff8f7dd277 R09: 1ffffffff1efba4e R10: dffffc0000000000 R11: fffffbfff1efba4f R12: dffffc0000000000 R13: ffff8880b88276c0 R14: ffff8880b88276c0 R15: 1ffff92001bb3f70 clock_was_set+0x63b/0x7c0 kernel/time/hrtimer.c:972 do_settimeofday64+0x2ec/0x5e0 kernel/time/timekeeping.c:1407 __do_sys_clock_settime kernel/time/posix-timers.c:1140 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1124 [inline] __x64_sys_clock_settime+0x22c/0x280 kernel/time/posix-timers.c:1124 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9370f8e969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9371dd4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00007f93711b6080 RCX: 00007f9370f8e969 RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000000 RBP: 00007f9371010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f93711b6080 R15: 00007ffddcfc08d8