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INFO: rcu detected stall in kvm_vcpu_ioctl

Status: upstream: reported on 2025/06/05 19:21
Reported-by: syzbot+20e139d318a0d1d22a4b@syzkaller.appspotmail.com
First crash: 192d, last: 18d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kvm_vcpu_ioctl (2) kvm-x86 1 1 494d 494d 0/29 auto-obsoleted due to no activity on 2024/11/06 13:35
upstream INFO: rcu detected stall in kvm_vcpu_ioctl (3) kvm-x86 1 2 289d 354d 0/29 auto-obsoleted due to no activity on 2025/05/30 15:19
upstream INFO: rcu detected stall in kvm_vcpu_ioctl mm 1 C error unreliable 251 1475d 2652d 0/29 closed as invalid on 2022/02/08 10:48
linux-4.19 INFO: rcu detected stall in kvm_vcpu_ioctl 1 C error 46 1510d 2165d 0/1 upstream: reported C repro on 2020/01/10 19:56
linux-4.14 INFO: rcu detected stall in kvm_vcpu_ioctl 1 C error 12 2066d 2224d 0/1 upstream: reported C repro on 2019/11/13 08:08
linux-4.19 BUG: soft lockup in kvm_vcpu_ioctl 1 C error 2 1688d 1691d 0/1 upstream: reported C repro on 2021/04/28 21:34
android-5-15 BUG: soft lockup in kvm_vcpu_ioctl 1 1 610d 610d 0/2 auto-obsoleted due to no activity on 2024/07/12 20:15

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8734/1:b..l P5134/1:b..l P8733/1:b..l
	(detected by 1, t=10502 jiffies, g=32545, q=11)
task:syz.8.1166      state:R  running task     stack:26464 pid: 8733 ppid:  6598 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9000313f2c0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 9c0ab9f7f1b87a00
RDX: 0000000000000000 RSI: ffffffff8a0b2f00 RDI: ffffffff8a59e580
RBP: ffffc9000313f3d0 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: ffffffff8c11c760
R13: 1ffff92000627e64 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 percpu_ref_get_many include/linux/percpu-refcount.h:202 [inline]
 percpu_ref_get include/linux/percpu-refcount.h:222 [inline]
 obj_cgroup_get include/linux/memcontrol.h:805 [inline]
 memcg_slab_post_alloc_hook mm/slab.h:320 [inline]
 slab_post_alloc_hook+0x191/0x380 mm/slab.h:526
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 mmu_memory_cache_alloc_obj virt/kvm/kvm_main.c:393 [inline]
 kvm_mmu_topup_memory_cache+0xde/0x200 virt/kvm/kvm_main.c:405
 mmu_topup_memory_caches arch/x86/kvm/mmu/mmu.c:748 [inline]
 kvm_mmu_load+0x11d/0x1b90 arch/x86/kvm/mmu/mmu.c:5067
 kvm_mmu_reload arch/x86/kvm/mmu.h:90 [inline]
 vcpu_enter_guest+0x61c5/0x7110 arch/x86/kvm/x86.c:9911
 vcpu_run arch/x86/kvm/x86.c:10181 [inline]
 kvm_arch_vcpu_ioctl_run+0xdea/0x1f40 arch/x86/kvm/x86.c:10418
 kvm_vcpu_ioctl+0x887/0xb80 virt/kvm/kvm_main.c:3894
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7fd758dcb749
RSP: 002b:00007fd757032038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd759021fa0 RCX: 00007fd758dcb749
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007fd758e4ff91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd759022038 R14: 00007fd759021fa0 R15: 00007ffd7fc7c238
 </TASK>
task:kworker/u4:14   state:R  running task     stack:25768 pid: 5134 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9000356faa0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: f8541fec86c12f00
RDX: 0000000000000000 RSI: ffffffff8a0b2f00 RDI: ffffffff8a59e580
RBP: ffffc9000356fbc0 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: ffffffff8c11c760
R13: 1ffff920006adf60 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0xc9/0x5c0 net/batman-adv/network-coding.c:723
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
task:syz.6.1167      state:R  running task     stack:27520 pid: 8734 ppid:  5399 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6596
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:404 [inline]
 filemap_map_pages+0x1031/0x1390 mm/filemap.c:3353
 do_fault_around mm/memory.c:4243 [inline]
 do_read_fault mm/memory.c:4258 [inline]
 do_fault mm/memory.c:4392 [inline]
 handle_pte_fault mm/memory.c:4650 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x257d/0x43b0 mm/memory.c:4883
 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7fd507b2e2ed
RSP: 002b:00007fff70c35f80 EFLAGS: 00010202
RAX: 000000110c320000 RBX: 00007fd5089d4720 RCX: 0000000000000002
RDX: 0000000000000694 RSI: 000000000000201a RDI: 0000000000000004
RBP: ffffffff81680694 R08: 00007fd507ea5038 R09: 00007fd507e91000
R10: 00007fd5076be008 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff81680375 R15: 00000000000002ee
 </TASK>
rcu: rcu_preempt kthread starved for 10587 jiffies! g32545 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27808 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 8718 Comm: syz.4.1162 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7fe1de4c36e0
Code: 44 24 20 0f 29 44 24 30 0f 29 44 24 40 48 8b 44 24 08 ff d0 48 83 c4 50 31 c0 5b 5d 41 5c 41 5d 41 5e c3 0f 1f 80 00 00 00 00 <c3> 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 c3 66 66 2e 0f 1f
RSP: 002b:00007fe1dc86bb38 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007fe1de85bfa8 RCX: 00007fe1de605749
RDX: 00007fe1dc86bb40 RSI: 00007fe1dc86bc70 RDI: 0000000000000011
RBP: 00007fe1de85bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe1de85c038 R14: 00007ffeaab24ea0 R15: 00007ffeaab24f88
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/26 22:09 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/09/02 12:29 linux-5.15.y 01879f56bdde 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/30 09:35 linux-5.15.y 3dea0e7f549e fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/12 21:12 linux-5.15.y 1c700860e8bc 98683f8f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/05 19:21 linux-5.15.y 1c700860e8bc 6b6b5f21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
* Struck through repros no longer work on HEAD.