INFO: rcu detected stall in unwind_next_frame (3)

Status: upstream: reported on 2026/05/13 02:27
Reported-by: syzbot+5a71420060e9f8be848d@syzkaller.appspotmail.com
First crash: 78d, last: 35d
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in unwind_next_frame (2) kernel 1 1 1070d 1070d 0/29 auto-obsoleted due to no activity on 2023/10/24 10:24
linux-6.1 INFO: rcu detected stall in unwind_next_frame (2) 1 1 855d 855d 0/3 auto-obsoleted due to no activity on 2024/07/04 19:31
upstream INFO: rcu detected stall in unwind_next_frame (5) prio:low ext4 1 syz, C error error 58 1d09h 289d 0/29 upstream: reported C repro on 2025/10/14 01:28
upstream INFO: rcu detected stall in unwind_next_frame (3) kernel 1 1 1003d 1003d 0/29 auto-obsoleted due to no activity on 2024/01/29 09:37
linux-6.1 INFO: rcu detected stall in unwind_next_frame 1 1 1021d 1021d 0/3 auto-obsoleted due to no activity on 2024/01/21 04:23
upstream INFO: rcu detected stall in unwind_next_frame (4) mm 1 7 641d 774d 0/29 auto-obsoleted due to no activity on 2025/01/25 06:35
linux-5.15 INFO: rcu detected stall in unwind_next_frame 1 1 340d 340d 0/3 auto-obsoleted due to no activity on 2025/12/01 20:02
linux-6.6 INFO: rcu detected stall in unwind_next_frame 1 1 22d 22d 0/2 upstream: reported on 2026/07/08 12:08
upstream INFO: rcu detected stall in unwind_next_frame kernel 1 2 2992d 2995d 8/29 fixed on 2018/07/09 18:05

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 5461 jiffies s: 5093 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4699 Comm: syz.7.32 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:hlock_id kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_acquire+0xf1c/0x7bd0 kernel/locking/lockdep.c:5037
Code: 11 49 c7 c7 ff ff ff ff c7 44 24 78 00 00 00 00 eb 06 b0 01 89 44 24 78 48 8b 44 24 38 42 0f b6 04 00 84 c0 0f 85 d4 59 00 00 <49> 8d 85 e0 0a 00 00 48 89 84 24 88 00 00 00 45 8b 24 24 48 83 7d
RSP: 0018:ffffc90000006a00 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 00000000000c4065 RCX: ffffffff816406d9
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90af2248
RBP: ffffc90000006c30 R08: dffffc0000000000 R09: 1ffffffff215e449
R10: dffffc0000000000 R11: fffffbfff215e44a R12: ffff88807b24c818
R13: ffff88807b24bc00 R14: ffff88807b24c7f8 R15: ffffffffffffffff
FS:  00007efd390c76c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31924220 CR3: 000000007e257000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 seqcount_lockdep_reader_access+0xcd/0x1d0 include/linux/seqlock.h:102
 timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
 ktime_get+0x7b/0x270 kernel/time/timekeeping.c:848
 hrtimer_forward_now include/linux/hrtimer.h:509 [inline]
 perf_swevent_hrtimer+0x4f8/0x630 kernel/events/core.c:10972
 __run_hrtimer kernel/time/hrtimer.c:1751 [inline]
 __hrtimer_run_queues+0x4e7/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_interrupt+0x399/0x980 kernel/time/hrtimer.c:1877
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:50 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:178 [inline]
RIP: 0010:unwind_next_frame+0x11f4/0x1fd0 arch/x86/kernel/unwind_orc.c:448
Code: 8a 48 8b 74 24 48 e8 8d 9d e6 08 e9 60 05 00 00 49 89 f4 48 89 f5 4c 89 e8 48 29 e8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 <48> 83 e0 fe 4c 8d 7c 45 00 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00
RSP: 0018:ffffc90000007420 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc900000074c8 RCX: 0000000000000000
RDX: ffffffff8f1799e0 RSI: ffffffff8e7ffd8c RDI: 0000000000000001
RBP: ffffffff8e7ffd8c R08: 0000000000000003 R09: 0000000000000005
R10: dffffc0000000000 R11: fffff52000000ea5 R12: ffffffff8e7ffd8c
R13: ffffffff8e7ffd8c R14: ffffffff88319d66 R15: ffffffff8e7ffd90
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 kmem_cache_free+0xf7/0x2a0 mm/slub.c:3709
 __netif_receive_skb_core+0x3217/0x38c0 net/core/dev.c:5593
 __netif_receive_skb_one_core net/core/dev.c:5617 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5733
 process_backlog+0x37c/0x710 net/core/dev.c:6061
 __napi_poll+0xbb/0x460 net/core/dev.c:6628
 napi_poll net/core/dev.c:6695 [inline]
 net_rx_action+0x622/0xbc0 net/core/dev.c:6809
 handle_softirqs+0x291/0x910 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:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5710
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc900038672d8 EFLAGS: 00000206
RAX: 3859c9b053008500 RBX: ffff88807b24bc00 RCX: 3859c9b053008500
RDX: ffff88807b24bc00 RSI: ffffffff8a8c2920 RDI: ffffffff8adee1a0
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff215e448
R10: dffffc0000000000 R11: fffffbfff215e449 R12: 0000000000000005
R13: 0000000000000246 R14: ffffffff8cb2db60 R15: ffff88807b24c7a8
 trace_call_bpf+0x19e/0x6b0 kernel/trace/bpf_trace.c:135
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10027
 perf_trace_lock+0x301/0x390 include/trace/events/lock.h:50
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0x8ad/0x920 kernel/locking/lockdep.c:5673
 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
 _raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 __kernfs_new_node+0x200/0x7f0 fs/kernfs/dir.c:625
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:690
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:1068
 cgroup_add_file kernel/cgroup/cgroup.c:4225 [inline]
 cgroup_addrm_files+0x80c/0xd50 kernel/cgroup/cgroup.c:4285
 css_populate_dir+0x157/0x3b0 kernel/cgroup/cgroup.c:1794
 cgroup_apply_control_enable+0x641/0xb00 kernel/cgroup/cgroup.c:3291
 cgroup_mkdir+0xc7f/0xe70 kernel/cgroup/cgroup.c:5789
 kernfs_iop_mkdir+0x23d/0x3d0 fs/kernfs/dir.c:1221
 vfs_mkdir+0x386/0x570 fs/namei.c:4114
 do_mkdirat+0x1d8/0x440 fs/namei.c:4139
 __do_sys_mkdirat fs/namei.c:4154 [inline]
 __se_sys_mkdirat fs/namei.c:4152 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4152
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7efd3819ce59
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:00007efd390c7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007efd38415fa0 RCX: 00007efd3819ce59
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007efd38232e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efd38416038 R14: 00007efd38415fa0 R15: 00007ffc6160f468
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/24 21:13 linux-6.1.y fdb6fcb41cc7 302586aa .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in unwind_next_frame
2026/05/13 02:26 linux-6.1.y ad16b162f21d a0949470 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in unwind_next_frame
* Struck through repros no longer work on HEAD.