rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 ticks this GP) idle=493/1/0x4000000000000000 softirq=60486/60486 fqs=0 (detected by 1, t=10506 jiffies, g=81889, q=1379) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 18952 Comm: syz.6.4464 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x2a/0x60 kernel/kcov.c:206 Code: 48 8b 04 24 65 48 8b 0d 74 4d 89 7e 65 8b 15 75 4d 89 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 <74> 2c 8b 91 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 48 8b RSP: 0018:ffffc90000007370 EFLAGS: 00000046 RAX: ffffffff819c0dfa RBX: 0000000000000001 RCX: ffff888029890000 RDX: 0000000000000100 RSI: ffffffff8a79f7e0 RDI: ffff888029890000 RBP: ffffc900000074b0 R08: ffffc90000007437 R09: ffffc90000007420 R10: dffffc0000000000 R11: fffff52000000e87 R12: 1ffff92000000e80 R13: ffffc90000007500 R14: dffffc0000000000 R15: ffff88802ae31dd8 FS: 00007fc049ad46c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3221fff8 CR3: 0000000059495000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: rcu_lock_release+0xa/0x40 include/linux/rcupdate.h:318 __perf_output_begin kernel/events/ring_buffer.c:262 [inline] perf_output_begin_forward+0x79b/0xa40 kernel/events/ring_buffer.c:271 __perf_event_output kernel/events/core.c:7804 [inline] perf_event_output_forward+0x19b/0x2e0 kernel/events/core.c:7822 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc90000007b00 EFLAGS: 00000206 RAX: 941dfd2d581fee00 RBX: 1ffff92000000f64 RCX: 941dfd2d581fee00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: ffffc90000007bd8 R08: ffff8880b903b30b R09: 1ffff11017207661 R10: dffffc0000000000 R11: ffffed1017207662 R12: ffffffff8c322f00 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4eb/0xb70 kernel/time/hrtimer.c:1749 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766 handle_softirqs+0x339/0x830 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804 Code: be ff ff ff ff e8 6c c1 67 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 16 2d 71 08 e8 21 e4 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c RSP: 0018:ffffc9000399f9e8 EFLAGS: 00000286 RAX: 941dfd2d581fee00 RBX: ffff8880b903a340 RCX: 941dfd2d581fee00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: 1ffff11017207613 R08: ffff8880b903b30b R09: 1ffff11017207661 R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffff110172075c1 R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921 context_switch kernel/sched/core.c:5052 [inline] __schedule+0x11f7/0x43c0 kernel/sched/core.c:6395 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __up_write kernel/locking/rwsem.c:1355 [inline] up_write+0x1e0/0x420 kernel/locking/rwsem.c:1604 inode_unlock include/linux/fs.h:792 [inline] __sock_release net/socket.c:654 [inline] sock_close+0x10f/0x240 net/socket.c:1345 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc04b8bc629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc049ad4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007fc04bb36180 RCX: 00007fc04b8bc629 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000b RBP: 00007fc04b952b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc04bb36218 R14: 00007fc04bb36180 R15: 00007ffe15afc9d8 rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g81889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=66979 rcu: rcu_preempt kthread starved for 10506 jiffies! g81889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27536 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9b/0x370 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 18952 Comm: syz.6.4464 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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 20 bc 10 0c 48 89 de 5b e9 37 42 44 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d 74 4d 89 7e 65 8b 15 75 4d 89 7e 81 e2 00 RSP: 0018:ffffc90000007958 EFLAGS: 00000046 RAX: 1ffff110172067af RBX: ffff8880b9033d78 RCX: ffff888029890000 RDX: 0000000000010100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000007a18 R08: ffff8880b903b1fb R09: 1ffff1101720763f R10: dffffc0000000000 R11: ffffed1017207640 R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff92000000f30 FS: 00007fc049ad46c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3221fff8 CR3: 0000000059495000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: irq_work_run_list+0x2f2/0x340 kernel/irq_work.c:172 __sysvec_irq_work+0x98/0x240 arch/x86/kernel/irq_work.c:22 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline] sysvec_irq_work+0x4a/0xc0 arch/x86/kernel/irq_work.c:17 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc90000007b00 EFLAGS: 00000206 RAX: 941dfd2d581fee00 RBX: 1ffff92000000f64 RCX: 941dfd2d581fee00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: ffffc90000007bd8 R08: ffff8880b903b30b R09: 1ffff11017207661 R10: dffffc0000000000 R11: ffffed1017207662 R12: ffffffff8c322f00 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4eb/0xb70 kernel/time/hrtimer.c:1749 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766 handle_softirqs+0x339/0x830 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4804 Code: be ff ff ff ff e8 6c c1 67 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 16 2d 71 08 e8 21 e4 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c RSP: 0018:ffffc9000399f9e8 EFLAGS: 00000286 RAX: 941dfd2d581fee00 RBX: ffff8880b903a340 RCX: 941dfd2d581fee00 RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800 RBP: 1ffff11017207613 R08: ffff8880b903b30b R09: 1ffff11017207661 R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffff110172075c1 R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921 context_switch kernel/sched/core.c:5052 [inline] __schedule+0x11f7/0x43c0 kernel/sched/core.c:6395 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __up_write kernel/locking/rwsem.c:1355 [inline] up_write+0x1e0/0x420 kernel/locking/rwsem.c:1604 inode_unlock include/linux/fs.h:792 [inline] __sock_release net/socket.c:654 [inline] sock_close+0x10f/0x240 net/socket.c:1345 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fc04b8bc629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc049ad4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007fc04bb36180 RCX: 00007fc04b8bc629 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000b RBP: 00007fc04b952b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc04bb36218 R14: 00007fc04bb36180 R15: 00007ffe15afc9d8