rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=993/1/0x4000000000000002 softirq=35019/35020 fqs=321 
	(detected by 0, t=10505 jiffies, g=43857, q=245)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 12526 Comm: syz.2.2777 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:226 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x4/0x80 kernel/kcov.c:293
Code: 77 22 89 ff 89 f6 4a c7 44 02 08 03 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 48 8b 04 24 <65> 48 8b 0d 44 36 89 7e 65 8b 15 45 36 89 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc90000dd0118 EFLAGS: 00000046
RAX: ffffffff81829b02 RBX: ffff88802a2b3a00 RCX: ffff888021c0d940
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000dd0218 R08: dffffc0000000000 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000001 R15: ffffffff8c36a140
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000580 CR3: 0000000053d0d000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 BPF_PROG_RUN_ARRAY include/linux/bpf.h:1432 [inline]
 trace_call_bpf+0x192/0x5b0 kernel/trace/bpf_trace.c:127
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10016
 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 d2 df 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:ffffc90000dd0440 EFLAGS: 00000206
RAX: affde094e2e6a800 RBX: 1ffff920001ba08c RCX: affde094e2e6a800
RDX: dffffc0000000000 RSI: ffffffff8a2b3100 RDI: ffffffff8a7a0700
RBP: ffffc90000dd0510 R08: ffffffff901d61b7 R09: 1ffffffff203ac36
R10: dffffc0000000000 R11: fffffbfff203ac37 R12: ffffffff8c323800
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 hsr_dev_xmit+0x276/0x2e0 net/hsr/hsr_device.c:247
 __netdev_start_xmit include/linux/netdevice.h:5036 [inline]
 netdev_start_xmit include/linux/netdevice.h:5050 [inline]
 xmit_one net/core/dev.c:3662 [inline]
 dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3678
 __dev_queue_xmit+0x1a9b/0x2f80 net/core/dev.c:4305
 br_send_bpdu_finish net/bridge/br_stp_bpdu.c:32 [inline]
 NF_HOOK include/linux/netfilter.h:302 [inline]
 br_send_bpdu+0x471/0x8d0 net/bridge/br_stp_bpdu.c:59
 br_send_config_bpdu+0x416/0x6b0 net/bridge/br_stp_bpdu.c:120
 br_transmit_config+0x3ba/0x5d0 net/bridge/br_stp.c:235
 br_config_bpdu_generation+0x11f/0x1d0 net/bridge/br_stp.c:394
 br_hello_timer_expired+0x97/0x1c0 net/bridge/br_stp_timer.c:37
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 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
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:seqcount_lockdep_reader_access+0x144/0x190 include/linux/seqlock.h:106
Code: 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 42 41 f7 c5 00 02 00 00 74 01 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 43 c7 44 27 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000329f3e0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: ffff88813fffb7c0 RCX: affde094e2e6a800
RDX: dffffc0000000000 RSI: ffffffff8a2b3100 RDI: ffffffff8a7a0700
RBP: ffffc9000329f4a0 R08: ffffffff901d60c7 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: dffffc0000000000
R13: 0000000000000a02 R14: ffffffff81b55237 R15: 1ffff92000653e7c
 read_seqbegin include/linux/seqlock.h:897 [inline]
 zone_span_seqbegin include/linux/memory_hotplug.h:83 [inline]
 page_outside_zone_boundaries mm/page_alloc.c:580 [inline]
 bad_range+0x77/0x2d0 mm/page_alloc.c:607
 rmqueue mm/page_alloc.c:3760 [inline]
 get_page_from_freelist+0x1b9c/0x1ca0 mm/page_alloc.c:4189
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 __get_free_pages+0x8/0x30 mm/page_alloc.c:5538
 tlb_next_batch mm/mmu_gather.c:30 [inline]
 __tlb_remove_page_size+0x1f2/0x3f0 mm/mmu_gather.c:84
 __tlb_remove_page include/asm-generic/tlb.h:460 [inline]
 zap_pte_range mm/memory.c:1387 [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+0x1093/0x2500 mm/memory.c:1576
 unmap_vmas+0x131/0x250 mm/memory.c:1653
 exit_mmap+0x3b9/0x640 mm/mmap.c:3216
 __mmput+0x115/0x3b0 kernel/fork.c:1127
 exit_mm+0x5f7/0x770 kernel/exit.c:551
 do_exit+0x5a9/0x20c0 kernel/exit.c:871
 do_group_exit+0x12e/0x300 kernel/exit.c:998
 __do_sys_exit_group kernel/exit.c:1009 [inline]
 __se_sys_exit_group kernel/exit.c:1007 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1007
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f97e0b52e59
Code: Unable to access opcode bytes at RIP 0x7f97e0b52e2f.
RSP: 002b:00007ffc4f598888 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f97e0b52e59
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc4f5988ec R08: 0000000000000000 R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000242
R13: 00000000000927c0 R14: 00000000000695b4 R15: 00007ffc4f598940
 </TASK>
rcu: rcu_preempt kthread starved for 8900 jiffies! g43857 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:27536 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 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
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 144 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <IRQ>
 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+0x843/0x1120 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+0x4b4/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 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
 </IRQ>
 <TASK>
 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 77 b8 4a 00 44 38 e3 75 10 66 90 0f 00 2d f9 db f3 08 fb f4 <e9> 16 ff ff ff fb e9 10 ff ff ff e8 27 30 88 08 89 f9 80 e1 07 38
RSP: 0018:ffffc900016fe5c0 EFLAGS: 00000246
RAX: 0a7e42d0929ee200 RBX: 0000000000000003 RCX: 0a7e42d0929ee200
RDX: dffffc0000000000 RSI: ffffffff8a2b3100 RDI: ffffffff8a7a0700
RBP: ffffc900016fe670 R08: ffffffff901d60c7 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: 0000000000000003
R13: ffff8880b903b154 R14: dffffc0000000000 R15: 1ffff920002dfcb8
 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+0x60f/0x9c0 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+0x1468/0x1740 mm/page_vma_mapped.c:-1
 page_mkclean_one+0x17d/0x3e0 mm/rmap.c:926
 rmap_walk_file+0x408/0x610 mm/rmap.c:2378
 rmap_walk mm/rmap.c:2396 [inline]
 page_mkclean+0x2f4/0x400 mm/rmap.c:1006
 clear_page_dirty_for_io+0x3f8/0x9f0 mm/page-writeback.c:2749
 mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2095
 mpage_process_page_bufs+0x6d8/0x8b0 fs/ext4/inode.c:2229
 mpage_prepare_extent_to_map+0xbc2/0xfe0 fs/ext4/inode.c:2657
 ext4_writepages+0xa9a/0x2df0 fs/ext4/inode.c:2785
 do_writepages+0x476/0x6e0 mm/page-writeback.c:2386
 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
 writeback_sb_inodes+0xa4e/0x1680 fs/fs-writeback.c:1940
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
 wb_writeback+0x46f/0xbe0 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+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>