INFO: rcu detected stall in unwind_get_return_address (2)

Status: upstream: reported on 2026/08/03 06:35
Reported-by: syzbot+2b156a772bffb877d6e7@syzkaller.appspotmail.com
First crash: 17d, last: 17d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in unwind_get_return_address bpf 1 1 688d 688d 0/29 auto-obsoleted due to no activity on 2024/12/29 10:05
linux-5.15 INFO: rcu detected stall in unwind_get_return_address 1 1 238d 238d 0/3 auto-obsoleted due to no activity on 2026/04/03 20:45
linux-6.1 INFO: rcu detected stall in unwind_get_return_address 1 1 181d 181d 0/3 auto-obsoleted due to no activity on 2026/05/31 04:58
upstream INFO: rcu detected stall in unwind_get_return_address (2) bpf 1 syz error error 1 250d 246d 0/29 auto-obsoleted due to no activity on 2026/03/22 18:27

Sample crash report:
Illegal XDP return value 16128, expect packet loss!
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=6a1/1/0x4000000000000002 softirq=21341/21342 fqs=5239 
	(detected by 1, t=10502 jiffies, g=29205, q=1193)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8969 Comm: syz.3.1203 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:mark_lock+0xfa/0x320 kernel/locking/lockdep.c:4610
Code: 31 ff 49 83 c7 50 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 14 8d 60 00 b8 01 00 00 00 45 85 27 74 50 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 e8 d6 b2 87 02 85 c0 74 c1 48 c7
RSP: 0018:ffffc90000007088 EFLAGS: 00000086
RAX: 0000000000000001 RBX: ffff888017f81dc0 RCX: ffffffff815d9204
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901ee0c0
RBP: 0000000000000009 R08: ffffffff901ee0c7 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: 0000000000000200
R13: dffffc0000000000 R14: ffff888017f82900 R15: ffffffff8fb76f90
FS:  00007fc94eac76c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557f1bc1b120 CR3: 0000000063056000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 mark_usage kernel/locking/lockdep.c:4512 [inline]
 __lock_acquire+0xd7b/0x7b50 kernel/locking/lockdep.c:4966
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 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:ffffc90000007b00 EFLAGS: 00000206
RAX: 4ded9e90bdff8d00 RBX: 1ffff92000000f64 RCX: 4ded9e90bdff8d00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200
RBP: ffffc90000007bd8 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 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]
 ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4ea/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 1f c1 88 f7 65 8b 05 90 e8 38 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000308f300 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 4ded9e90bdff8d00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000308f390 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: dffffc0000000000
R13: 1ffffffff1864600 R14: ffffffff8c323ab0 R15: 1ffff92000611e60
 rcu_report_exp_rnp kernel/rcu/tree_exp.h:223 [inline]
 rcu_preempt_deferred_qs_irqrestore+0x855/0xbd0 kernel/rcu/tree_plugin.h:562
 rcu_read_unlock_special+0x3d9/0x4a0 kernel/rcu/tree_plugin.h:673
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 is_bpf_text_address+0x24f/0x270 kernel/bpf/core.c:727
 kernel_text_address kernel/extable.c:151 [inline]
 __kernel_text_address+0x9a/0x100 kernel/extable.c:105
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 file_free fs/file_table.c:55 [inline]
 __fput+0x5d9/0x8c0 fs/file_table.c:324
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 get_signal+0x123e/0x12e0 kernel/signal.c:2681
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fc95086f019
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:00007fc94eac7028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: 0000000000000014 RBX: 00007fc950af6fa0 RCX: 00007fc95086f019
RDX: 0000000000000010 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007fc95090600c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc950af7038 R14: 00007fc950af6fa0 R15: 00007ffe7ccf5898
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/03 06:34 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in unwind_get_return_address
* Struck through repros no longer work on HEAD.