INFO: rcu detected stall in debug_check_no_obj_freed

Status: upstream: reported C repro on 2025/11/11 10:45
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+ad978f266c4a8b74fb60@syzkaller.appspotmail.com
First crash: 257d, last: 225d
Fix bisection: the issue occurs on the latest tested release (bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/02 linux-6.6.y (ToT) 4791134e4aeb C [report] INFO: rcu detected stall in smp_call_function
2025/11/14 upstream (ToT) 6da43bbeb691 C Didn't crash
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: soft lockup in debug_check_no_obj_freed serial 1 syz 2 645d 645d 0/29 auto-obsoleted due to no activity on 2025/01/27 15:36
linux-5.15 INFO: rcu detected stall in debug_check_no_obj_freed origin:lts-only 1 syz error 2 119d 258d 0/3 upstream: reported syz repro on 2025/11/10 02:51
upstream INFO: rcu detected stall in debug_check_no_obj_freed fs 1 1 539d 539d 0/29 auto-obsoleted due to no activity on 2025/05/03 06:53
upstream BUG: soft lockup in debug_check_no_obj_freed (2) kernel 1 1 232d 232d 0/29 closed as invalid on 2026/01/09 17:04
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2026/05/30 07:16 22m fix candidate upstream error job log
2026/03/24 11:46 1m fix candidate upstream error job log
2026/02/20 17:41 9m fix candidate upstream error job log
2026/01/21 15:13 38m fix candidate upstream error job log
2026/01/16 06:02 2h02m bisect fix linux-6.6.y OK (0) job log
2025/12/13 08:19 1h49m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10498 ticks this GP) idle=dacc/1/0x4000000000000000 softirq=12114/12116 fqs=4547
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1137420          0            0
rcu: 	cputime:    19308      33181           36   ==> 52490(ms)
rcu: 	(t=10500 jiffies g=8937 q=1682 ncpus=2)
CPU: 0 PID: 5966 Comm: syz.2.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa9/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 ea 7c 13 f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> f2 f8 e2 f6 65 8b 05 e3 41 8b 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900000073a0 EFLAGS: 00000206
RAX: 62b6c0ead77b7e00 RBX: 0000000000000a06 RCX: 62b6c0ead77b7e00
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: ffffc90000007430 R08: ffffffff90da85f7 R09: 1ffffffff21b50be
R10: dffffc0000000000 R11: fffffbfff21b50bf R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8880775286b8 R15: 1ffff92000000e74
FS:  000055557c12b500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001cb0c000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 wiphy_work_queue+0x151/0x1a0 net/wireless/core.c:1638
 __ieee80211_queue_skb_to_iface net/mac80211/rx.c:232 [inline]
 ieee80211_queue_skb_to_iface net/mac80211/rx.c:243 [inline]
 ieee80211_rx_h_mgmt+0x4f8/0x6f0 net/mac80211/rx.c:3989
 ieee80211_rx_handlers+0x64f0/0xb0c0 net/mac80211/rx.c:4147
 ieee80211_invoke_rx_handlers net/mac80211/rx.c:4177 [inline]
 ieee80211_prepare_and_rx_handle+0x25fe/0x61d0 net/mac80211/rx.c:5035
 ieee80211_rx_for_interface net/mac80211/rx.c:5120 [inline]
 __ieee80211_rx_handle_packet net/mac80211/rx.c:5293 [inline]
 ieee80211_rx_list+0x26c9/0x2fe0 net/mac80211/rx.c:5428
 ieee80211_rx_napi+0x1aa/0x3c0 net/mac80211/rx.c:5451
 ieee80211_rx include/net/mac80211.h:4971 [inline]
 ieee80211_handle_queued_frames+0x106/0x1a0 net/mac80211/main.c:319
 tasklet_action_common+0x2eb/0x4c0 kernel/softirq.c:809
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa9/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 ea 7c 13 f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> f2 f8 e2 f6 65 8b 05 e3 41 8b 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90003617ba0 EFLAGS: 00000206
RAX: 62b6c0ead77b7e00 RBX: 0000000000000a06 RCX: 62b6c0ead77b7e00
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: 0000000000000001
RBP: ffffc90003617c20 R08: ffffffff8e4a8d6f R09: 1ffffffff1c951ad
R10: dffffc0000000000 R11: fffffbfff1c951ae R12: dffffc0000000000
R13: ffff88801db5e960 R14: ffffffff97116238 R15: 1ffff920006c2f74
 __debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
 debug_check_no_obj_freed+0x51f/0x540 lib/debugobjects.c:1020
 slab_free_hook mm/slub.c:1786 [inline]
 slab_free_freelist_hook+0xd2/0x1b0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 kmem_cache_free+0xf8/0x280 mm/slub.c:3852
 file_free fs/file_table.c:77 [inline]
 __fput+0x61c/0x970 fs/file_table.c:397
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 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:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7812d8f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff63bddd48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000020d36 RCX: 00007f7812d8f6c9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000363bde03f
R10: 0000001b2df20000 R11: 0000000000000246 R12: 00007f7812fe5fac
R13: 00007f7812fe5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/11 10:44 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in debug_check_no_obj_freed
* Struck through repros no longer work on HEAD.