rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=1e6c/1/0x4000000000000000 softirq=99426/99427 fqs=6 rcu: (detected by 1, t=10502 jiffies, g=112585, q=1665 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 18938 Comm: syz.1.2914 Not tainted 6.6.101-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x82/0x90 kernel/kcov.c:315 Code: 8d 52 28 4d 39 ca 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 05 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 8b 04 24 RSP: 0018:ffffc90000007c68 EFLAGS: 00000006 RAX: ffffffff889c45ac RBX: 0000000000000001 RCX: 0000000000010000 RDX: ffff88802242bc00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000002 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f7c R12: ffff8880685c0340 R13: ffff8880685c0000 R14: ffff88802c4b0000 R15: ffff88802ecac000 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000735030 CR3: 000000000cb30000 CR4: 00000000003506f0 Call Trace: advance_sched+0x16c/0xc80 net/sched/sch_taprio.c:938 __run_hrtimer kernel/time/hrtimer.c:1755 [inline] __hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1819 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline] __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x82/0x90 kernel/kcov.c:315 Code: 8d 52 28 4d 39 ca 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 05 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 8b 04 24 RSP: 0018:ffffc9000b3a6e78 EFLAGS: 00000293 RAX: ffffffff813ad67c RBX: ffffc9000b3a6ee8 RCX: 0000000000000000 RDX: ffff88802242bc00 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: ffffc9000b3a6f01 R09: 0000000000000000 R10: ffffc9000b3a6ee8 R11: fffff52001674de9 R12: ffffc9000b3a6e80 R13: ffffc9000b3a6f08 R14: 1ffff92001674ddd R15: 1ffff92001674de2 unwind_done arch/x86/include/asm/unwind.h:50 [inline] __unwind_start+0x56c/0x7e0 arch/x86/kernel/unwind_orc.c:757 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf7/0x1f0 mm/page_owner.c:128 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149 reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1154 [inline] free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475 release_pages+0x1fa0/0x2220 mm/swap.c:1022 __folio_batch_release+0x71/0xe0 mm/swap.c:1042 folio_batch_release include/linux/pagevec.h:83 [inline] shmem_undo_range+0x5d0/0x1a40 mm/shmem.c:1027 shmem_truncate_range mm/shmem.c:1136 [inline] shmem_evict_inode+0x273/0xa70 mm/shmem.c:1265 evict+0x486/0x870 fs/inode.c:705 __dentry_kill+0x431/0x650 fs/dcache.c:611 dentry_kill+0xb8/0x290 fs/dcache.c:-1 dput+0xfe/0x1e0 fs/dcache.c:918 __fput+0x5e5/0x970 fs/file_table.c:392 task_work_run+0x1ce/0x250 kernel/task_work.c:239 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0x90b/0x23c0 kernel/exit.c:883 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024 get_signal+0x12fc/0x1400 kernel/signal.c:2902 arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb73138ebe9 Code: Unable to access opcode bytes at 0x7fb73138ebbf. RSP: 002b:00007ffcca684348 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000000 RBX: 0000000000161324 RCX: 00007fb73138ebe9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fb7315b5fac RBP: 0000000000000032 R08: 0000000000745d1e R09: 00000008ca68463f R10: 00007ffcca684440 R11: 0000000000000246 R12: 00007fb7315b5fac R13: 00007ffcca684440 R14: 0000000000161356 R15: 00007ffcca684460 rcu: rcu_preempt kthread starved for 10286 jiffies! g112585 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:27432 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 PID: 16345 Comm: kworker/u4:18 Not tainted 6.6.101-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x17/0x60 kernel/kcov.c:216 Code: 48 8b 3d 8c f1 c4 0c 48 89 de 5b e9 63 75 56 00 cc cc cc f3 0f 1e fa 48 8b 04 24 65 48 8b 0d 60 24 7e 7e 65 8b 15 61 24 7e 7e <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 RSP: 0018:ffffc9000361f778 EFLAGS: 00000202 RAX: ffffffff817ac297 RBX: 1ffff110171c87d9 RCX: ffff8880237f9e00 RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000361f900 R08: ffffffff90da3527 R09: 1ffffffff21b46a4 R10: dffffc0000000000 R11: fffffbfff21b46a5 R12: ffff8880b8e43ec8 R13: dffffc0000000000 R14: ffff8880b8f3d588 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b5f400218 CR3: 000000000cb30000 CR4: 00000000003506e0 Call Trace: csd_lock_wait kernel/smp.c:311 [inline] smp_call_function_many_cond+0xdf7/0x1130 kernel/smp.c:855 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1023 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2222 [inline] text_poke_bp_batch+0x617/0x930 arch/x86/kernel/alternative.c:2494 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x123/0x240 kernel/jump_label.c:207 static_key_enable+0x1a/0x20 kernel/jump_label.c:220 toggle_allocation_gate+0xaa/0x250 mm/kfence/core.c:831 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293