rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=32bc/1/0x4000000000000000 softirq=17674/17675 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6532/1:b..l rcu: (detected by 0, t=10505 jiffies, g=12365, q=371 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6515 Comm: syz.2.168 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:_find_first_zero_bit+0x0/0x80 lib/find_bit.c:148 Code: 89 34 24 e8 f2 02 7e fd 48 8b 44 24 08 48 8b 34 24 e9 7b ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 89 f0 48 85 f6 74 51 55 48 bd 00 00 00 00 00 fc ff RSP: 0018:ffffc9000f877d48 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff88807d7c3050 RCX: 1ffff1100faf84b9 RDX: 0000000000000002 RSI: 0000000000000002 RDI: ffff88807d7c3050 RBP: ffff88807d84c980 R08: 0000000000000000 R09: fffff52001f0ef9c R10: 0000000000000003 R11: ffff88807d84d4b0 R12: 0000000000000007 R13: ffff88807d7c2640 R14: 0000000000000002 R15: 0000000000000002 FS: 00007f2b6ae206c0(0000) GS:ffff888124a09000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b305e1000 CR3: 0000000031baf000 CR4: 00000000003526f0 Call Trace: find_first_zero_bit include/linux/find.h:393 [inline] __mm_get_cid kernel/sched/sched.h:3744 [inline] mm_get_cid kernel/sched/sched.h:3759 [inline] sched_mm_cid_fork+0x517/0xcc0 kernel/sched/core.c:10578 bprm_execve fs/exec.c:1776 [inline] bprm_execve+0x4ff/0x1620 fs/exec.c:1729 do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1859 do_execveat fs/exec.c:1944 [inline] __do_sys_execveat fs/exec.c:2018 [inline] __se_sys_execveat fs/exec.c:2012 [inline] __x64_sys_execveat+0xda/0x120 fs/exec.c:2012 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2b69f8f749 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:00007f2b6ae20038 EFLAGS: 00000246 ORIG_RAX: 0000000000000142 RAX: ffffffffffffffda RBX: 00007f2b6a1e5fa0 RCX: 00007f2b69f8f749 RDX: 0000000000000000 RSI: 0000200000000040 RDI: ffffffffffffff9c RBP: 00007f2b6a013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2b6a1e6038 R14: 00007f2b6a1e5fa0 R15: 00007ffcf4242ff8 task:syz.3.174 state:R running task stack:26456 pid:6532 tgid:6532 ppid:5815 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_release+0x183/0x2d0 kernel/locking/lockdep.c:5893 Code: 0f c1 05 58 c3 17 12 83 f8 01 0f 85 03 01 00 00 9c 58 f6 c4 02 0f 85 ee 00 00 00 41 f7 c5 00 02 00 00 74 01 fb 48 8b 44 24 10 <65> 48 2b 05 ed 7b 17 12 0f 85 32 01 00 00 48 83 c4 18 5b 41 5c 41 RSP: 0018:ffffc9001b09f6f8 EFLAGS: 00000206 RAX: 22663c02a3dd3200 RBX: ffffffff8e3c9620 RCX: ffffc9001b09f704 RDX: 0000000000000000 RSI: ffffffff8da9bf6a RDI: ffffffff8bf24280 RBP: 0000000000000001 R08: 0000000000000001 R09: 00000000ffffffff R10: 0000000000000002 R11: 0000000000008622 R12: ffffffff816cb9a4 R13: 0000000000000206 R14: ffff8880787ba4c0 R15: 0000000000000001 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:897 [inline] class_rcu_destructor include/linux/rcupdate.h:1195 [inline] unwind_next_frame+0x3f9/0x20a0 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556 __call_rcu_common.constprop.0+0xa5/0xa10 kernel/rcu/tree.c:3119 destroy_inode+0x12c/0x1b0 fs/inode.c:401 evict+0x599/0xad0 fs/inode.c:861 iput_final fs/inode.c:1951 [inline] iput.part.0+0x621/0x1190 fs/inode.c:2003 iput+0x35/0x40 fs/inode.c:1966 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:467 __dentry_kill+0x1d0/0x600 fs/dcache.c:670 finish_dput+0x76/0x480 fs/dcache.c:879 dput.part.0+0x451/0x570 fs/dcache.c:928 dput+0x1f/0x30 fs/dcache.c:920 __fput+0x51c/0xb70 fs/file_table.c:476 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0xfb/0x540 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f35bd58f749 RSP: 002b:00007fffcef56728 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f35bd7e7da0 RCX: 00007f35bd58f749 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f35bd7e7da0 R08: 000000000000038c R09: 00000018cef56a1f R10: 00000000003ffa50 R11: 0000000000000246 R12: 000000000001a5be R13: 00007f35bd7e6090 R14: ffffffffffffffff R15: 00007fffcef56840 rcu: rcu_preempt kthread starved for 10505 jiffies! g12365 f0x0 RCU_GP_WAIT_FQS(5) ->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:28176 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 1153 Comm: kworker/u8:8 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: iou_exit io_ring_exit_work RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xe21/0x15e0 kernel/smp.c:877 Code: b5 5a 0c 00 f3 90 41 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 b6 05 00 00 8b 43 08 31 ff 83 e0 01 41 89 c6 89 c6 e8 2f 55 0c 00 <45> 85 f6 75 d0 4c 8b 74 24 10 e8 80 5a 0c 00 e8 7b 5a 0c 00 41 83 RSP: 0018:ffffc900044176f0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8540cc0 RCX: ffffffff81b289e1 RDX: ffff88802839a4c0 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff88802839aff0 R12: dffffc0000000000 R13: ffffed10170a8199 R14: 0000000000000001 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888124909000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c296b7c CR3: 000000000e184000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1043 on_each_cpu include/linux/smp.h:71 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2711 [inline] smp_text_poke_batch_finish+0x27b/0xdb0 arch/x86/kernel/alternative.c:2921 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 jump_label_update+0x376/0x550 kernel/jump_label.c:919 __static_key_slow_dec_cpuslocked.part.0+0xef/0x120 kernel/jump_label.c:315 __static_key_slow_dec_cpuslocked kernel/jump_label.c:297 [inline] __static_key_slow_dec kernel/jump_label.c:321 [inline] static_key_slow_dec+0x7c/0xc0 kernel/jump_label.c:336 io_ring_ctx_free io_uring/io_uring.c:2866 [inline] io_ring_exit_work+0xe8e/0x1130 io_uring/io_uring.c:3073 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246