[v5.15] INFO: rcu detected stall in hsr_prune_nodes

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3330a8d33e08 Linux 5.15.201
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=118e43e6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=8e3f8a9e41bbf9d4249d
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/805fe5d5059e/disk-3330a8d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/27b51f6fcd64/vmlinux-3330a8d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c9998071ec80/bzImage-3330a8d3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8e3f8a...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (1 GPs behind) idle=81f/1/0x4000000000000000 softirq=22137/22138 fqs=2974
(t=10500 jiffies g=31377 q=2451)
NMI backtrace for cpu 0
CPU: 0 PID: 8728 Comm: syz.3.993 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x6ea/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+0x4ad/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+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x13e/0x1c0 kernel/softirq.c:408
Code: 8a e8 a6 fc 72 08 65 66 8b 05 ae 5b ba 7e 66 85 c0 75 54 bf 01 00 00 00 e8 bf 24 09 00 e8 9a 10 36 00 fb 65 8b 05 5a 32 b9 7e <85> c0 75 05 e8 a9 3f b7 ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc90000007a40 EFLAGS: 00000286
RAX: 0000000000000101 RBX: 0000000000000201 RCX: a2f7888051a65e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800
RBP: ffffc90000007ad8 R08: ffffffff901d31bf R09: 1ffffffff203a637
R10: dffffc0000000000 R11: fffffbfff203a638 R12: ffffffff89a48c05
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff92000000f48
spin_unlock_bh include/linux/spinlock.h:409 [inline]
hsr_prune_nodes+0xa45/0xa90 net/hsr/hsr_framereg.c:527
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: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:ffffc9000318f308 EFLAGS: 00000282
RAX: a2f7888051a65e00 RBX: ffff8880b903a340 RCX: a2f7888051a65e00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f800
RBP: 1ffff11017207613 R08: ffffffff901d3177 R09: 1ffffffff203a62e
R10: dffffc0000000000 R11: fffffbfff203a62f 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
__raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:404 [inline]
copy_pte_range mm/memory.c:1106 [inline]
copy_pmd_range mm/memory.c:1167 [inline]
copy_pud_range mm/memory.c:1204 [inline]
copy_p4d_range mm/memory.c:1228 [inline]
copy_page_range+0x288f/0x3230 mm/memory.c:1301
dup_mmap kernel/fork.c:615 [inline]
dup_mm kernel/fork.c:1466 [inline]
copy_mm+0xc86/0x13f0 kernel/fork.c:1518
copy_process+0x17eb/0x3e20 kernel/fork.c:2290
kernel_clone+0x23f/0x990 kernel/fork.c:2679
__do_sys_clone kernel/fork.c:2796 [inline]
__se_sys_clone kernel/fork.c:2780 [inline]
__x64_sys_clone+0x19a/0x210 kernel/fork.c:2780
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: 0033:0x7f47787d0799
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:00007f4776a29fd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f4778a49fa0 RCX: 00007f47787d0799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000061000600
RBP: 00007f4778866bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f4778a4a038 R14: 00007f4778a49fa0 R15: 00007fff8f9b9ca8
</TASK>


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