INFO: rcu detected stall in kvm_vcpu_release

Status: upstream: reported on 2026/08/30 17:48
Reported-by: syzbot+cd595e8262aba000e56e@syzkaller.appspotmail.com
First crash: 13h21m, last: 13h21m
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kvm_vcpu_release kernel 1 1 2683d 2683d 0/29 auto-closed as invalid on 2019/10/24 01:16
upstream INFO: rcu detected stall in kvm_vcpu_release (2) fs 1 1 815d 815d 0/29 auto-obsoleted due to no activity on 2024/09/05 03:45
linux-5.15 INFO: rcu detected stall in kvm_vcpu_release 1 1 828d 828d 0/3 auto-obsoleted due to no activity on 2024/09/02 00:50
upstream INFO: rcu detected stall in kvm_vcpu_release (3) prio:high mm 1 1 132d 132d 0/29 auto-obsoleted due to no activity on 2026/07/19 08:55

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12553/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=90805, q=131 ncpus=1)
task:syz.6.1820      state:R  running task     stack:25640 pid:12553 ppid:11869  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_offset lib/xarray.c:146 [inline]
RIP: 0010:xas_descend+0x59/0x460 lib/xarray.c:205
Code: 80 3c 38 00 74 08 4c 89 f7 e8 13 14 5e f7 4d 8b 36 4c 89 e8 48 c1 e8 03 48 89 44 24 18 42 0f b6 04 38 84 c0 0f 85 ad 03 00 00 <45> 0f b6 65 00 bf 40 00 00 00 44 89 e6 e8 a5 98 05 f7 41 83 fc 3f
RSP: 0018:ffffc900045577d0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc900045578a8 RCX: 0000000000080000
RDX: ffffc9000e2e7000 RSI: 0000000000068676 RDI: 0000000000068677
RBP: ffff88802ec17442 R08: ffff88801af33c00 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000002 R12: 1ffff920008aaf17
R13: ffff88802ec17440 R14: 0000000000000000 R15: dffffc0000000000
 xas_load lib/xarray.c:244 [inline]
 xas_find+0x1d8/0xa50 lib/xarray.c:1250
 xa_find+0x18d/0x2b0 lib/xarray.c:2041
 kvm_destroy_vcpus+0xcd/0x260 virt/kvm/kvm_main.c:529
 kvm_arch_destroy_vm+0x34b/0x430 arch/x86/kvm/x86.c:12623
 kvm_destroy_vm virt/kvm/kvm_main.c:1339 [inline]
 kvm_put_kvm+0xdbf/0x1a20 virt/kvm/kvm_main.c:1373
 kvm_vcpu_release+0x57/0x60 virt/kvm/kvm_main.c:3888
 __fput+0x221/0x940 fs/file_table.c:418
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 get_signal+0x11da/0x1390 kernel/signal.c:2687
 arch_do_signal_or_restart+0xc2/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xee/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:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f96eb59e159
RSP: 002b:00007f96ec3e7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 00007f96eb825fa0 RCX: 00007f96eb59e159
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 000000000000000a
RBP: 00007f96eb635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f96eb826038 R14: 00007f96eb825fa0 R15: 00007ffe9da68998
 </TASK>
rcu: rcu_preempt kthread starved for 234 jiffies! g90805 f0x0 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:26504 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7011
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:_raw_spin_unlock_irqrestore+0xf0/0x120 kernel/locking/spinlock.c:195
Code: 8b 05 3c 66 6a 75 85 c0 74 3c 48 c7 04 24 0e 36 e0 45 4b c7 04 27 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 48 75 23 <48> 8d 65 e0 5b 41 5c 41 5e 41 5f 5d c3 e8 7e 48 f6 ff f7 c3 00 02
RSP: 0018:ffffc90000167a80 EFLAGS: 00000246
RAX: 5f2ac82339c9d000 RBX: 0000000000000a06 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: 00000000ffffffff
RBP: ffffc90000167b18 R08: ffffffff8e8c872f R09: 1ffffffff1d190e5
R10: dffffc0000000000 R11: fffffbfff1d190e6 R12: dffffc0000000000
R13: ffff88805d935120 R14: ffffffff974b15b0 R15: 1ffff9200002cf50
 debug_object_free+0x2c2/0x470 lib/debugobjects.c:912
 destroy_timer_on_stack kernel/time/timer.c:812 [inline]
 schedule_timeout+0x1a1/0x2d0 kernel/time/timer.c:2172
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 12575 Comm: syz.2.1824 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:finish_task_switch+0x267/0x8f0 kernel/sched/core.c:5256
Code: 31 09 85 c0 0f 84 30 01 00 00 48 85 db 0f 85 4f 01 00 00 0f 1f 44 00 00 4c 89 e7 e8 73 87 3b 09 e8 4e 1a 30 00 fb 4c 8b 65 b8 <49> 8d bc 24 00 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0
RSP: 0018:ffffc90004537880 EFLAGS: 00000282
RAX: a0ffc772d854d100 RBX: 0000000000000000 RCX: a0ffc772d854d100
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1d3360
RBP: ffffc900045378d0 R08: ffffffff8e8c872f R09: 1ffffffff1d190e5
R10: dffffc0000000000 R11: fffffbfff1d190e6 R12: ffff88807f875a00
R13: 1ffff110171c79a1 R14: dffffc0000000000 R15: ffff8880b8e3cd08
FS:  00007fadb085d6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 000000005f474000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5385 [inline]
 __schedule+0x15b6/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 futex_wait_queue+0x138/0x1b0 kernel/futex/waitwake.c:355
 futex_wait+0x1e9/0x5c0 kernel/futex/waitwake.c:656
 do_futex+0x2ff/0x3e0 kernel/futex/syscalls.c:134
 __do_sys_futex kernel/futex/syscalls.c:211 [inline]
 __se_sys_futex+0x3a9/0x440 kernel/futex/syscalls.c:192
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fadaf99e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fadb085d0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007fadafc25fa8 RCX: 00007fadaf99e159
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fadafc25fa8
RBP: 00007fadafc25fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fadafc26038 R14: 00007ffcc70be420 R15: 00007ffcc70be508
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/30 17:47 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in kvm_vcpu_release
* Struck through repros no longer work on HEAD.