[v6.6] INFO: rcu detected stall in preempt_schedule_thunk (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d1cfde2d5d15 Linux 6.6.143
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=145222ae580000
kernel config: https://syzkaller.appspot.com/x/.config?x=441765643cbfb8d
dashboard link: https://syzkaller.appspot.com/bug?extid=b98205de49d8b623e209
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/65f04d62b48f/disk-d1cfde2d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6a803b737439/vmlinux-d1cfde2d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e621f8d5e524/bzImage-d1cfde2d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b98205...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10436 ticks this GP) idle=a4d4/1/0x4000000000000000 softirq=114191/114221 fqs=5142
rcu: hardirqs softirqs csw/system
rcu: number: 1678940 269 0
rcu: cputime: 17942 34545 31 ==> 52520(ms)
rcu: (t=10504 jiffies g=151025 q=1847 ncpus=2)
CPU: 0 PID: 28926 Comm: syz.1.6183 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:182 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_cmp8+0x1f/0x80 kernel/kcov.c:293
Code: 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 8b 04 24 65 48 8b 0d d0 d0 7c 7e 65 8b 15 d1 d0 7c 7e 81 e2 00 01 ff 00 74 11 <81> fa 00 01 00 00 75 57 83 b9 1c 16 00 00 00 74 4e 8b 91 f8 15 00
RSP: 0018:ffffc90000007390 EFLAGS: 00000206
RAX: ffffffff813b25b2 RBX: ffffffff81000000 RCX: ffff888038eeda00
RDX: 0000000000000100 RSI: ffffffff8ac00000 RDI: ffffffff86364eba
RBP: ffffc90000007400 R08: ffffc90000007530 R09: 000000000000000b
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000007c68
R13: ffffc90000007468 R14: ffffffff86364eba R15: 0000000000000001
FS: 00007f3f544af6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555734d04e8 CR3: 0000000052fda000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
unwind_next_frame+0x1e2/0x2990 arch/x86/kernel/unwind_orc.c:-1
arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
kmem_cache_alloc_node+0x1af/0x310 mm/slub.c:3540
__alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
skb_copy+0x126/0x700 net/core/skbuff.c:1984
mac80211_hwsim_tx_frame_no_nl+0xcb2/0x11e0 drivers/net/wireless/virtual/mac80211_hwsim.c:1840
mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176
mac80211_hwsim_beacon_tx+0x3df/0x770 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
__iterate_interfaces+0x225/0x4c0 net/mac80211/util.c:766
ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
__run_hrtimer kernel/time/hrtimer.c:1754 [inline]
__hrtimer_run_queues+0x525/0xc10 kernel/time/hrtimer.c:1818
hrtimer_run_softirq+0x177/0x290 kernel/time/hrtimer.c:1835
handle_softirqs+0x27d/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5255
Code: 26 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 93 3b 30 09 e8 7e 0b 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc9000563f820 EFLAGS: 00000282
RAX: f05e8d9f44bc5400 RBX: 0000000000000000 RCX: f05e8d9f44bc5400
RDX: dffffc0000000000 RSI: ffffffff8acacb60 RDI: ffffffff8b1c7be0
RBP: ffffc9000563f870 R08: ffffffff8e8ae5ef R09: 1ffffffff1d15cbd
R10: dffffc0000000000 R11: fffffbfff1d15cbe R12: ffff888038eeda00
R13: 1ffff110171c79a9 R14: dffffc0000000000 R15: ffff8880b8e3cd48
context_switch kernel/sched/core.c:5384 [inline]
__schedule+0x15b6/0x4660 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irq+0x40/0x50 kernel/locking/spinlock.c:202
task_work_run+0x197/0x260 kernel/task_work.c:241
get_signal+0x11da/0x1390 kernel/signal.c:2679
arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3f5359ce59
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:00007f3f544af028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000006 RBX: 00007f3f53815fa0 RCX: 00007f3f5359ce59
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000480
RBP: 00007f3f53632e6f R08: 000000000000000a R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3f53816038 R14: 00007f3f53815fa0 R15: 00007ffdcd36fbe8
</TASK>


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