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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6e2fd6534337 Linux 5.15.213
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1143a5b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=a95c25be94fc9ac420fb
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5d11c5de6164/disk-6e2fd653.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2cd88808b8bc/vmlinux-6e2fd653.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6abd34d756f0/bzImage-6e2fd653.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a95c25...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 GPs behind) idle=4f9/1/0x4000000000000002 softirq=29931/29932 fqs=5182
(detected by 1, t=10502 jiffies, g=41833, q=5120)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 12094 Comm: syz.2.2702 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:436 [inline]
RIP: 0010:lock_acquire+0x1a2/0x400 kernel/locking/lockdep.c:5625
Code: 0f 94 c1 4c 89 e7 8b 74 24 1c 89 da 48 8b 4c 24 28 4c 8b 44 24 30 6a 00 6a 00 ff 75 10 ff 74 24 38 e8 a2 03 00 00 48 83 c4 20 <48> c7 c7 80 3e 2b 8a e8 72 49 63 08 b8 ff ff ff ff 65 0f c1 05 f5
RSP: 0018:ffffc900000071e0 EFLAGS: 00000082
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901ee0c0
RBP: ffffc900000072f8 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: ffffffff8c31ef60
R13: 1ffff92000000e48 R14: 0000000000000046 R15: dffffc0000000000
FS: 00007f078dc796c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f14ecacdd58 CR3: 0000000023af7000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
__perf_event_output kernel/events/core.c:7800 [inline]
perf_event_output_forward+0xbc/0x2e0 kernel/events/core.c:7822
__perf_event_overflow+0x35f/0x550 kernel/events/core.c:9515
perf_swevent_overflow kernel/events/core.c:9591 [inline]
perf_swevent_event+0x4b8/0x540 kernel/events/core.c:9629
perf_tp_event+0x324/0xbe0 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 02 20 9d 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:ffffc900000079c0 EFLAGS: 00000206
RAX: 55d88f4a00d0a300 RBX: 1ffff92000000f3c RCX: 55d88f4a00d0a300
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200
RBP: ffffc90000007aa0 R08: ffffffff901ee1bf R09: 1ffffffff203dc37
R10: dffffc0000000000 R11: fffffbfff203dc38 R12: ffffffff8c323400
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]
hsr_announce+0x29a/0x310 net/hsr/hsr_device.c:410
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1699 [inline]
__run_timers+0x56c/0x810 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x336/0x830 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:array_index_mask_nospec+0x0/0x10 arch/x86/include/asm/barrier.h:41
Code: 06 e9 a4 c8 c7 00 e9 9f c8 b0 00 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 48 c7 c0 da ff ff ff c3 0f 1f 84 00 00 00 00 00 <48> 81 ff c1 01 00 00 48 19 c0 c3 00 00 cc cc 00 48 8d 87 80 00 00
RSP: 0018:ffffc900032aff18 EFLAGS: 00000206
RAX: 00000000000000ca RBX: ffffc900032aff20 RCX: 55d88f4a00d0a300
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 00000000000000ca
RBP: ffffc900032aff48 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 0000000000000000
R13: 0000000000000000 R14: ffffc900032aff58 R15: 00000000000000ca
do_syscall_x64 arch/x86/entry/common.c:49 [inline]
do_syscall_64+0x3e/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f078fa21019
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:00007f078dc790e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f078fca8fa8 RCX: 00007f078fa21019
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f078fca8fac
RBP: 00007f078fca8fa0 R08: 0010f66a917bbd68 R09: 0000000000000000
R10: 000000000000001e R11: 0000000000000246 R12: 0000000000000000
R13: 00007f078fca9038 R14: 00007ffd2c336e00 R15: 00007ffd2c336ee8
</TASK>


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