rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (2 ticks this GP) idle=880c/1/0x4000000000000000 softirq=14098/14098 fqs=10
rcu: (detected by 1, t=10502 jiffies, g=13781, q=1769 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 4994 Comm: udevd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline]
RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline]
RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline]
RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline]
RIP: 0010:do_raw_spin_lock+0x138/0x2f0 kernel/locking/spinlock_debug.c:116
Code: df be 04 00 00 00 49 89 d6 e8 84 44 91 00 48 8d 7c 24 40 be 04 00 00 00 e8 75 44 91 00 8b 44 24 40 b9 01 00 00 00 f0 0f b1 0b <0f> 85 20 01 00 00 43 c6 44 34 04 f8 65 8b 1d 89 c9 c9 11 43 0f b6
RSP: 0018:ffffc90000007d20 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8880b86281c0 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000007d60
RBP: ffffc90000007dc8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000fac R12: 1ffff92000000fa8
R13: ffff8880b86281c8 R14: dffffc0000000000 R15: 1ffff110170c5039
FS: 00007fd84fd95880(0000) GS:ffff888124f4e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555c42d9f8 CR3: 000000007e766000 CR4: 00000000003526f0
Call Trace:
__run_hrtimer kernel/time/hrtimer.c:2036 [inline]
__hrtimer_run_queues+0x466/0xa10 kernel/time/hrtimer.c:2096
hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:check_kcov_mode kernel/kcov.c:194 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x36/0x90 kernel/kcov.c:300
Code: f8 18 a6 11 65 8b 0d 19 19 a6 11 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 24 17 00 00 00 74 52 8b 8a f8 16 00 00 <83> f9 03 75 47 48 8b 8a 00 17 00 00 44 8b 8a fc 16 00 00 49 c1 e1
RSP: 0018:ffffc90002def980 EFLAGS: 00000246
RAX: ffffffff81b3e190 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88807e253e00 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 0000000000000001 R08: ffffffff90579137 R09: 1ffffffff20af226
R10: dffffc0000000000 R11: fffffbfff20af227 R12: ffff8880278125f8
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88801e690f50
variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
cpumask_test_cpu include/linux/cpumask.h:651 [inline]
cpu_online include/linux/cpumask.h:1233 [inline]
trace_hrtimer_setup+0x70/0x200 include/trace/events/timer.h:193
debug_setup kernel/time/hrtimer.c:516 [inline]
hrtimer_setup+0x34/0x50 kernel/time/hrtimer.c:1924
copy_signal+0x358/0x650 kernel/fork.c:1752
copy_process+0x1df3/0x4390 kernel/fork.c:2286
kernel_clone+0x2d7/0x940 kernel/fork.c:2748
__do_sys_clone kernel/fork.c:2889 [inline]
__se_sys_clone kernel/fork.c:2873 [inline]
__x64_sys_clone+0x1b6/0x230 kernel/fork.c:2873
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd84f6f1636
Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffd32fa4510 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffd32fa4518 RCX: 00007fd84f6f1636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000560a2849d910 R08: 0000000000000000 R09: 0000000000000210
R10: 00007fd84fd95b50 R11: 0000000000000246 R12: 00007ffd32fa48d0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
rcu: rcu_preempt kthread starved for 8067 jiffies! g13781 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:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 5750 Comm: syz.2.3 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x11e6/0x15f0 kernel/smp.c:912
Code: c0 75 7a 41 8b 1e 89 de 83 e6 01 31 ff e8 e2 22 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 8e 1e 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 73 1e 0c
RSP: 0000:ffffc9000506f820 EFLAGS: 00000293
RAX: ffffffff81bae58d RBX: dffffc0000000000 RCX: ffff8880266a8000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000506f970 R08: ffffffff90579137 R09: 1ffffffff20af226
R10: dffffc0000000000 R11: fffffbfff20af227 R12: 1ffff110170c85fd
R13: ffff8880b873c448 R14: ffff8880b8642fe8 R15: 0000000000000000
FS: 000055555c41a500(0000) GS:ffff88812504e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2b9c026080 CR3: 000000007745a000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1077
__flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
flush_tlb_mm_range+0x5c4/0x1090 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:104
wp_page_copy mm/memory.c:3941 [inline]
do_wp_page+0x3d52/0x4c70 mm/memory.c:4336
handle_pte_fault mm/memory.c:6395 [inline]
__handle_mm_fault mm/memory.c:6517 [inline]
handle_mm_fault+0x1490/0x3080 mm/memory.c:6686
do_user_addr_fault+0xa4d/0x1340 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7f2b9bc5a766
Code: 00 00 00 00 53 48 89 fb 48 85 ff 74 47 80 3d 94 af ef 00 00 75 1e 80 3d 5f 79 3c 00 00 75 55 48 8b 43 18 48 c7 00 00 00 00 00 43 48 00 5b c3 0f 1f 40 00 8b 3b 31 d2 31 c0 be 68 63 00 00 e8
RSP: 002b:00007f2b9c14fba0 EFLAGS: 00010246
RAX: 00007f2b9b7ff000 RBX: 00007f2b9c026038 RCX: 0000000000000001
RDX: 00007f2b9c025fa0 RSI: 0000000000000003 RDI: 00007f2b9c026038
RBP: 0000000000001d27 R08: 00007f2b9c025fa0 R09: 00007f2b9c14fa47
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b9c025fac R14: 00007f2b9c025fa8 R15: 00007f2b9c025fa0