syzbot

 sign-in | mailing list | source | docs
🐞 Open [1495]
≡ Subsystems
🐞 Fixed [6678]
🐞 Invalid [17140]
⬇ Missing Backports [214]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

INFO: rcu detected stall in kvm_dev_ioctl (3)

Status: closed as invalid on 2020/01/09 08:13
Subsystems: mm
[Documentation on labels]
First crash: 2118d, last: 2118d
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in kvm_dev_ioctl 1 1 491d 491d 0/3 auto-obsoleted due to no activity on 2024/10/01 03:25
upstream INFO: rcu detected stall in kvm_dev_ioctl (2) mm 1 1 2119d 2119d 0/29 closed as invalid on 2020/01/08 05:23
linux-6.6 INFO: rcu detected stall in kvm_dev_ioctl 1 1 77d 77d 0/2 upstream: reported on 2025/08/10 13:11
upstream INFO: rcu detected stall in kvm_dev_ioctl (5) mm 1 9 255d 545d 0/29 auto-obsoleted due to no activity on 2025/05/14 19:07
upstream INFO: rcu detected stall in kvm_dev_ioctl (4) mm 1 1 1064d 1064d 0/29 auto-obsoleted due to no activity on 2023/04/10 15:34
upstream INFO: rcu detected stall in kvm_dev_ioctl mm 1 4 2154d 2155d 0/29 closed as invalid on 2019/12/04 14:04

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8516
	(detected by 0, t=10503 jiffies, g=7181, q=720)
syz-executor.0  R  running task    27896  8516   8494 0x0000400a
Call Trace:
 <IRQ>
 sched_show_task+0x40f/0x560 kernel/sched/core.c:5954
 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:190 [inline]
 print_other_cpu_stall kernel/rcu/tree_stall.h:398 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:538 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0x16b1/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:free_thread_stack+0x151/0x590 kernel/fork.c:280
Code: 31 f6 e8 02 8d 6f 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 73 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 55 94 6a 00 48 8b 3b be fc ff ff ff e8 28 04 00
RSP: 0018:ffffc900027e7a78 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11011ae7871 RBX: ffff88808d73c388 RCX: 0000000000000000
RDX: ffffc90001e79000 RSI: 0000000000000000 RDI: ffffea00028ac740
RBP: ffffc900027e7ab0 R08: 000000000003a728 R09: ffffed10148e4ed1
R10: ffffed10148e4ed1 R11: 0000000000000000 R12: ffff888090f5c120
R13: dffffc0000000000 R14: 1ffff110121eb824 R15: ffff8880a4727678
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_notrace+0xdb/0x120 kernel/sched/core.c:4309
 ___preempt_schedule_notrace+0x16/0x27 arch/x86/entry/thunk_64.S:51
 rcu_is_watching+0x82/0xa0 kernel/rcu/tree.c:923
 rcu_read_unlock include/linux/rcupdate.h:667 [inline]
 memcg_kmem_get_cache+0x2e8/0x570 mm/memcontrol.c:2807
 slab_pre_alloc_hook mm/slab.h:572 [inline]
 slab_alloc mm/slab.c:3306 [inline]
 kmem_cache_alloc_trace+0x8c/0x2f0 mm/slab.c:3549
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:716 [inline]
 kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3519 [inline]
 kvm_dev_ioctl+0x807/0x2110 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3571
 do_vfs_ioctl+0x70b/0x1a30 fs/ioctl.c:47
 ksys_ioctl fs/ioctl.c:749 [inline]
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:754
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45af49
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb086fd2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb086fd36d4
R13: 00000000004c44de R14: 00000000004dadb0 R15: 00000000ffffffff
rcu: rcu_preempt kthread starved for 10487 jiffies! g7181 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    28984    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/01/08 10:19 upstream ae6088216ce4 6738e0b3 .config console log report ci-upstream-kasan-gce-smack-root
2020/01/08 09:24 upstream ae6088216ce4 6738e0b3 .config console log report ci-upstream-kasan-gce-smack-root
2020/01/08 07:06 upstream ae6088216ce4 6738e0b3 .config console log report ci-upstream-kasan-gce-smack-root
* Struck through repros no longer work on HEAD.