[v6.1] INFO: rcu detected stall in htab_map_free

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1989cd3d56e2 Linux 6.1.167
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=177ab3da580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0605c5af04d7603
dashboard link: https://syzkaller.appspot.com/bug?extid=32f3871eaed19a5d8224
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/3e0cf5574b81/disk-1989cd3d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0c1152de55b1/vmlinux-1989cd3d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3fe87e3166b1/bzImage-1989cd3d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+32f387...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2666 jiffies s: 56645 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 10134 Comm: kworker/u4:29 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound bpf_map_free_deferred
RIP: 0010:__lock_acquire+0x1039/0x7d10 kernel/locking/lockdep.c:-1
Code: e9 01 f0 89 ca c1 c2 08 29 ce 31 f2 01 c1 29 d0 41 89 d6 41 c1 c6 10 41 31 c6 01 ca 44 89 f3 c1 c3 13 44 29 f1 31 cb 41 01 d6 <29> da 41 89 dc 41 c1 c4 04 41 31 d4 48 c7 c0 a8 13 20 8e 48 c1 e8
RSP: 0018:ffffc900001e0400 EFLAGS: 00000882
RAX: 0000000042b1310e RBX: 00000000a1606fe7 RCX: 00000000bec1d0ac
RDX: 0000000049a5a9f8 RSI: 00000000ad744f38 RDI: ffffffff90af7240
RBP: ffffc900001e0650 R08: dffffc0000000000 R09: 1ffffffff215ee48
R10: dffffc0000000000 R11: fffffbfff215ee49 R12: 0000000025d1dec9
R13: 00000000ad0db31b R14: 00000000818f0dec R15: ffff888053930b78
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30763fff CR3: 00000000763e5000 CR4: 00000000003506e0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
rcu_read_lock include/linux/rcupdate.h:791 [inline]
trace_call_bpf+0xe0/0x6b0 kernel/trace/bpf_trace.c:134
perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
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 33 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0ac0 EFLAGS: 00000206
RAX: 4f6ea6852b5a5e00 RBX: 1ffff9200003c160 RCX: 4f6ea6852b5a5e00
RDX: dffffc0000000000 RSI: ffffffff8a8c10a0 RDI: ffffffff8adf0d20
RBP: ffffc900001e0bb0 R08: ffffffff90af72df R09: 1ffffffff215ee5b
R10: dffffc0000000000 R11: fffffbfff215ee5c R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
rcu_read_unlock include/linux/rcupdate.h:823 [inline]
ieee80211_iterate_active_interfaces_atomic+0x156/0x170 net/mac80211/util.c:826
mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
__run_hrtimer kernel/time/hrtimer.c:1747 [inline]
__hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lockdep_unregister_key+0x4e8/0x550 kernel/locking/lockdep.c:6370
Code: 71 aa 90 48 c7 c6 20 e6 64 81 e8 73 a8 07 00 e8 de bb 07 00 e9 5c fc ff ff e8 74 df c8 08 41 f7 c4 00 02 00 00 74 d1 fb 84 db <75> d0 eb e1 0f 0b eb 88 0f 0b e9 f8 fe ff ff 0f 0b e9 45 ff ff ff
RSP: 0018:ffffc9000da27aa0 EFLAGS: 00000202
RAX: dffffc0000000000 RBX: ffff888018692401 RCX: 4f6ea6852b5a5e00
RDX: 0000000000000001 RSI: ffffffff8a8c1d80 RDI: ffffffff8adf0d20
RBP: ffffc9000da27b70 R08: ffffffff90ac8207 R09: 1ffffffff2159040
R10: dffffc0000000000 R11: fffffbfff2159041 R12: 0000000000000a07
R13: ffff888018692441 R14: ffffffff90ac71a8 R15: 1ffff92001b44f58
htab_map_free+0x8d1/0x9b0 kernel/bpf/hashtab.c:1543
process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>


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