syzbot

 sign-in | mailing list | source | docs
🐞 Open [1504]
≡ Subsystems
🐞 Fixed [6667]
🐞 Invalid [17083]
⬇ Missing Backports [214]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

INFO: rcu detected stall in unwind_next_frame (2)

Status: auto-obsoleted due to no activity on 2023/10/24 10:24
Subsystems: kernel
[Documentation on labels]
First crash: 788d, last: 788d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in unwind_next_frame (2) 1 1 573d 573d 0/3 auto-obsoleted due to no activity on 2024/07/04 19:31
upstream INFO: rcu detected stall in unwind_next_frame (5) fs 1 syz error 17 20h49m 7d14h 0/29 upstream: reported syz repro on 2025/10/14 01:28
upstream INFO: rcu detected stall in unwind_next_frame (3) kernel 1 1 721d 721d 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 739d 739d 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 359d 492d 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 58d 58d 0/3 upstream: reported on 2025/08/23 20:02
upstream INFO: rcu detected stall in unwind_next_frame kernel 1 2 2710d 2713d 8/29 fixed on 2018/07/09 18:05

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=15276 jiffies, g=15193, q=118 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 15276 (4294972618-4294957342), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 15276 jiffies! g15193 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:29072 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0xee1/0x59f0 kernel/sched/core.c:6695
 schedule+0xe7/0x1b0 kernel/sched/core.c:6771
 schedule_timeout+0x157/0x2c0 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x1ec/0xa50 kernel/rcu/tree.c:1613
 rcu_gp_kthread+0x249/0x380 kernel/rcu/tree.c:1812
 kthread+0x33a/0x430 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.5.0-rc7-next-20230825-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:lock_release+0x3c3/0x680 kernel/locking/lockdep.c:5761
Code: 58 f6 c4 02 0f 85 c8 01 00 00 48 f7 04 24 00 02 00 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df 48 01 c5 48 c7 45 00 00 00 00 00 <c7> 45 08 00 00 00 00 48 8b 84 24 88 00 00 00 65 48 2b 04 25 28 00
RSP: 0018:ffffc90000007cc8 EFLAGS: 00000082
RAX: dffffc0000000000 RBX: ffffffff8ece4810 RCX: ffffffff816889e5
RDX: 0000000000000000 RSI: ffffffff8ae92820 RDI: 0000000000000000
RBP: fffff52000000f9b R08: 0000000000000000 R09: fffffbfff1d9c252
R10: ffffffff8ece1297 R11: ffffc90000007ff8 R12: ffffffff8cbab260
R13: ffff88804a4b0000 R14: ffff888021345340 R15: ffff88804a4b2000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdbbd2c66e4 CR3: 00000000509f5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 rcu_lock_release include/linux/rcupdate.h:308 [inline]
 rcu_read_unlock include/linux/rcupdate.h:782 [inline]
 advance_sched+0x6e0/0xc60 net/sched/sch_taprio.c:998
 __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
 __hrtimer_run_queues+0x203/0xc10 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1063 [inline]
 __sysvec_apic_timer_interrupt+0x105/0x3f0 arch/x86/kernel/apic/apic.c:1080
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1074
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:__sanitizer_cov_trace_cmp4+0x0/0x20 kernel/kcov.c:277
Code: ff 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 8b 0c 24 0f b7 d6 0f b7 f7 bf 02 00 00 00 e9 38 ff ff ff 0f 1f 84 00 00 00 00 00 <f3> 0f 1e fa 48 8b 0c 24 89 f2 89 fe bf 04 00 00 00 e9 1a ff ff ff
RSP: 0018:ffffc900001577d8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc90000157860 RCX: 0000000000000100
RDX: 1ffff9200002af0c RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 1ffff11004238e63 R12: 0000000000000001
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000001
 unwind_next_frame+0x117b/0x2390 arch/x86/kernel/unwind_orc.c:664
 arch_stack_walk+0xfa/0x170 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x96/0xd0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
 slab_free mm/slub.c:3809 [inline]
 kmem_cache_free+0xf0/0x480 mm/slub.c:3831
 rcu_do_batch kernel/rcu/tree.c:2139 [inline]
 rcu_core+0x7fb/0x1bb0 kernel/rcu/tree.c:2403
 __do_softirq+0x218/0x965 kernel/softirq.c:553
 run_ksoftirqd kernel/softirq.c:921 [inline]
 run_ksoftirqd+0x31/0x60 kernel/softirq.c:913
 smpboot_thread_fn+0x67d/0xa00 kernel/smpboot.c:164
 kthread+0x33a/0x430 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/08/25 10:16 linux-next 626932085009 03d9c195 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in unwind_next_frame
* Struck through repros no longer work on HEAD.