syzbot


INFO: rcu detected stall in sys_unlink (5)

Status: upstream: reported on 2025/09/25 16:42
Reported-by: syzbot+5854e0c59e957bb696cd@syzkaller.appspotmail.com
First crash: 19h15m, last: 19h15m
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in sys_unlink (4) 1 1 177d 177d 0/3 auto-obsoleted due to no activity on 2025/07/10 21:02
linux-5.15 INFO: rcu detected stall in sys_unlink (3) 1 1 326d 326d 0/3 auto-obsoleted due to no activity on 2025/02/11 14:08
upstream INFO: rcu detected stall in sys_unlink (2) kernel 1 2 977d 1062d 0/29 auto-obsoleted due to no activity on 2023/04/22 20:06
upstream INFO: rcu detected stall in sys_unlink (3) tomoyo mm 1 C error 200 2d14h 774d 0/29 upstream: reported C repro on 2023/08/13 23:42
linux-6.1 INFO: rcu detected stall in sys_unlink (2) 1 8 2d10h 183d 0/3 upstream: reported on 2025/03/27 11:38
linux-6.1 INFO: rcu detected stall in sys_unlink 1 4 393d 612d 0/3 auto-obsoleted due to no activity on 2024/12/07 03:28
linux-5.15 INFO: rcu detected stall in sys_unlink (2) 1 3 445d 457d 0/3 auto-obsoleted due to no activity on 2024/10/15 13:02
linux-6.6 INFO: rcu detected stall in sys_unlink 1 3 56d 67d 0/2 upstream: reported on 2025/07/20 18:19
upstream INFO: rcu detected stall in sys_unlink kasan mm 1 1 1153d 1153d 0/29 auto-obsoleted due to no activity on 2022/10/29 07:23
linux-5.15 INFO: rcu detected stall in sys_unlink 1 1 562d 562d 0/3 auto-obsoleted due to no activity on 2024/06/20 14:47
android-5-15 BUG: soft lockup in sys_unlink 1 7 505d 527d 0/2 auto-obsoleted due to no activity on 2024/08/07 01:29

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=0ff/1/0x4000000000000002 softirq=72566/72567 fqs=5246 
	(detected by 1, t=10502 jiffies, g=98073, q=850)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 18551 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:202
Code: 66 2e 0f 1f 84 00 00 00 00 00 53 48 89 fb e8 17 00 00 00 48 8b 3d 00 c9 f1 0b 48 89 de 5b e9 47 9e 43 00 00 00 cc cc 00 00 cc <48> 8b 04 24 65 48 8b 0d 94 a4 8a 7e 65 8b 15 95 a4 8a 7e 81 e2 00
RSP: 0018:ffffc90000007138 EFLAGS: 00000046
RAX: ffffffff8196e2ce RBX: 1ffff11017206a4a RCX: ffff888021170000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000073a8 R08: dffffc0000000000 R09: fffffbfff1ad323e
R10: fffffbfff1ad323e R11: 1ffffffff1ad323d R12: ffff8880b9035250
R13: ffff8880242b3bb0 R14: 0000000000000000 R15: 0000000000000000
FS:  000055558fb5e500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc2b296e68 CR3: 000000004f0e0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000200000000300
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_tp_event_match kernel/events/core.c:10000 [inline]
 perf_tp_event+0x269/0xb50 kernel/events/core.c:10046
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2be/0x380 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+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ad 13 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007600 EFLAGS: 00000206
RAX: 3dd7faf787fcfb00 RBX: 1ffff92000000ec4 RCX: 3dd7faf787fcfb00
RDX: dffffc0000000000 RSI: ffffffff8a0b1820 RDI: ffffffff8a59a480
RBP: ffffc900000076e0 R08: dffffc0000000000 R09: fffffbfff1ff7833
R10: fffffbfff1ff7833 R11: 1ffffffff1ff7832 R12: ffffffff8c120b00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:771 [inline]
 ndisc_send_skb+0xdc4/0x14a0 net/ipv6/ndisc.c:521
 ndisc_send_ns+0x63c/0x840 net/ipv6/ndisc.c:655
 ndisc_solicit+0x2f8/0x4e0 net/ipv6/ndisc.c:747
 neigh_probe net/core/neighbour.c:1017 [inline]
 neigh_timer_handler+0xaa9/0xfe0 net/core/neighbour.c:1099
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 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:seqcount_lockdep_reader_access+0x17b/0x1c0 include/linux/seqlock.h:106
Code: 00 4d 85 e4 75 16 e8 54 cc 0f 00 eb 15 e8 4d cc 0f 00 e8 88 ef 40 08 4d 85 e4 74 ea e8 3e cc 0f 00 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 66 43 c7 44 3e 09 00 00 43 c6 44 3e 0b 00
RSP: 0018:ffffc9000337fb80 EFLAGS: 00000293
RAX: ffffffff8167fee2 RBX: 0000000000000000 RCX: ffff888021170000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000337fc28 R08: dffffc0000000000 R09: fffffbfff1ff782c
R10: fffffbfff1ff782c R11: 1ffffffff1ff782b R12: 0000000000000200
R13: dffffc0000000000 R14: 1ffff9200066ff70 R15: dffffc0000000000
 ktime_get_coarse_real_ts64+0x36/0x120 kernel/time/timekeeping.c:2244
 current_time+0x86/0x2b0 fs/inode.c:2391
 shmem_unlink+0x181/0x260 mm/shmem.c:2955
 vfs_unlink+0x385/0x600 fs/namei.c:4280
 do_unlinkat+0x382/0x6f0 fs/namei.c:4348
 __do_sys_unlink fs/namei.c:4396 [inline]
 __se_sys_unlink fs/namei.c:4394 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4394
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe37c81a477
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 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:00007ffc2b297618 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe37c81a477
RDX: 00007ffc2b297640 RSI: 00007ffc2b2976d0 RDI: 00007ffc2b2976d0
RBP: 00007ffc2b2976d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc2b298760
R13: 00007fe37c89dd7d R14: 00000000000a1fc7 R15: 00007ffc2b2987a0
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/25 16:42 linux-5.15.y 43bb85222e53 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_unlink
* Struck through repros no longer work on HEAD.