rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (1 ticks this GP) idle=7bf/1/0x4000000000000000 softirq=37481/37481 fqs=304
(detected by 1, t=10503 jiffies, g=53989, q=273)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15702 Comm: syz.1.3644 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:check_preemption_disabled+0x0/0x110 lib/smp_processor_id.c:13
Code: 00 00 48 c7 c7 20 eb 32 8a e8 2c 01 00 00 65 ff 0d 31 2d 41 76 5b c3 00 00 cc 48 c7 c7 e0 4a 7a 8a 48 c7 c6 20 4b 7a 8a eb 00 <55> 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44
RSP: 0000:ffffc9000316ee90 EFLAGS: 00000093
RAX: ffffffff81988cdf RBX: ffff88801f22d988 RCX: ffff88802a505940
RDX: 0000000000000000 RSI: ffffffff8a32bbc0 RDI: ffffffff8a7a4b40
RBP: ffff88801f22ddf8 R08: ffff88801f22ddfb R09: 1ffff11003e45bbf
R10: dffffc0000000000 R11: ffffed1003e45bc0 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd98d6d7780 CR3: 0000000062f53000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000180 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
__perf_event_account_interrupt+0x2b/0x280 kernel/events/core.c:9432
__perf_event_overflow+0x9a/0x550 kernel/events/core.c:9484
perf_swevent_overflow kernel/events/core.c:9601 [inline]
perf_swevent_event+0x4b8/0x540 kernel/events/core.c:9639
perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
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 82 fc 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: 0000:ffffc9000316f420 EFLAGS: 00000206
RAX: 212f4c557333d300 RBX: 1ffff9200062de88 RCX: 212f4c557333d300
RDX: dffffc0000000000 RSI: ffffffff8a2b2b60 RDI: ffffffff8a7a4b40
RBP: ffffc9000316f4f0 R08: ffffffff910150c7 R09: 1ffffffff2202a18
R10: dffffc0000000000 R11: fffffbfff2202a19 R12: ffffffff8d123400
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]
__unlock_page_memcg+0xea/0x100 mm/memcontrol.c:2093
zap_pte_range mm/memory.c:1384 [inline]
zap_pmd_range mm/memory.c:1505 [inline]
zap_pud_range mm/memory.c:1534 [inline]
zap_p4d_range mm/memory.c:1555 [inline]
unmap_page_range+0xee4/0x2410 mm/memory.c:1576
unmap_vmas+0x131/0x250 mm/memory.c:1653
exit_mmap+0x3b9/0x640 mm/mmap.c:3216
__mmput+0x115/0x390 kernel/fork.c:1133
exit_mm+0x632/0x7b0 kernel/exit.c:557
do_exit+0x5b8/0x2110 kernel/exit.c:877
do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
get_signal+0x7eb/0x12e0 kernel/signal.c:2913
arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:157 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:323
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7f504b41a559
Code: Unable to access opcode bytes at RIP 0x7f504b41a52f.
RSP: 002b:00007f50496720e8 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 00007f504b6a1fa8 RCX: 00007f504b41a559
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f504b6a1fac
RBP: 00007f504b6a1fa0 R08: 000a285c230648c4 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f504b6a2038 R14: 00007ffd1b929b60 R15: 00007ffd1b929c48
rcu: rcu_preempt kthread starved for 8985 jiffies! g53989 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:27248 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 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/0x11f0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
kthread+0x42e/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:
NMI backtrace for cpu 1
CPU: 1 PID: 14546 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x845/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918
Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 47 a5 4a 00 44 38 e3 75 10 66 90 0f 00 2d 49 d9 f3 08 fb f4 16 ff ff ff fb e9 10 ff ff ff e8 b7 6c 8d 08 89 f9 80 e1 07 38
RSP: 0018:ffffc9000309e5a0 EFLAGS: 00000246
RAX: 59dacb4d7fa26000 RBX: 0000000000000003 RCX: 59dacb4d7fa26000
RDX: dffffc0000000000 RSI: ffffffff8a2b2b60 RDI: ffffffff8a7a4b40
RBP: ffffc9000309e650 R08: ffffffff910150c7 R09: 1ffffffff2202a18
R10: dffffc0000000000 R11: fffffbfff2202a19 R12: 0000000000000003
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff92000613cb4
pv_wait arch/x86/include/asm/paravirt.h:597 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x605/0x9b0 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115
page_vma_mapped_walk+0x13ee/0x16e0 mm/page_vma_mapped.c:-1
page_mkclean_one+0x17d/0x3e0 mm/rmap.c:926
rmap_walk_file+0x407/0x610 mm/rmap.c:2378
rmap_walk mm/rmap.c:2396 [inline]
page_mkclean+0x2f5/0x400 mm/rmap.c:1006
clear_page_dirty_for_io+0x3f9/0x9f0 mm/page-writeback.c:2749
mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2095
mpage_process_page_bufs+0x6c6/0x8a0 fs/ext4/inode.c:2229
mpage_prepare_extent_to_map+0xc48/0x1080 fs/ext4/inode.c:2657
ext4_writepages+0x9bb/0x2d40 fs/ext4/inode.c:2785
do_writepages+0x493/0x700 mm/page-writeback.c:2386
__writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
wb_writeback+0x45e/0xbc0 fs/fs-writeback.c:2116
wb_check_old_data_flush fs/fs-writeback.c:2216 [inline]
wb_do_writeback fs/fs-writeback.c:2269 [inline]
wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287