INFO: rcu detected stall in kvm_dev_ioctl (2)

Status: auto-obsoleted due to no activity on 2026/05/23 10:23
Reported-by: syzbot+45d460eb4e2a719dfe68@syzkaller.appspotmail.com
First crash: 213d, last: 180d
▶ ▼ Similar bugs (10)
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 780d 780d 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 2408d 2408d 0/29 closed as invalid on 2020/01/08 05:23
linux-6.6 INFO: rcu detected stall in kvm_dev_ioctl 1 1 366d 366d 0/2 auto-obsoleted due to no activity on 2025/11/18 13:11
upstream INFO: rcu detected stall in kvm_dev_ioctl (5) mm 1 9 544d 834d 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 1353d 1353d 0/29 auto-obsoleted due to no activity on 2023/04/10 15:34
upstream INFO: rcu detected stall in kvm_dev_ioctl (3) mm 1 3 2407d 2407d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in kvm_dev_ioctl mm 1 4 2443d 2444d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in kvm_dev_ioctl (6) fs 1 4 292d 441d 0/29 auto-obsoleted due to no activity on 2026/01/21 11:19
linux-4.19 BUG: soft lockup in kvm_dev_ioctl 1 1 1918d 1918d 0/1 auto-closed as invalid on 2021/09/08 20:48
android-5-15 BUG: soft lockup in kvm_dev_ioctl 1 1 816d 816d 0/2 auto-obsoleted due to no activity on 2024/08/16 05:28

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P20156/1:b..l
	(detected by 0, t=10502 jiffies, g=130089, q=5 ncpus=2)
task:syz.7.3570      state:R  running task     stack:26544 pid:20156 ppid:8383   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_is_held_type+0x14e/0x190 kernel/locking/lockdep.c:5710
Code: 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 48 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e <41> 5f 5d c3 0f 0b 48 c7 c7 20 12 8c 8a e8 00 12 00 00 65 c7 05 75
RSP: 0018:ffffc90003e8f570 EFLAGS: 00000286
RAX: 0000000000000001 RBX: ffff888055654b02 RCX: a315fe5761a61900
RDX: ffff88807c25bb80 RSI: ffffffff8a8c23a0 RDI: ffffffff8adf0d20
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff215ea48
R10: dffffc0000000000 R11: fffffbfff215ea49 R12: ffff888141256828
R13: ffffc90003e8f5e0 R14: ffffc90003e8f5c8 R15: ffff88807c25c688
 xa_head include/linux/xarray.h:1182 [inline]
 xas_start+0x292/0x770 lib/xarray.c:188
 xas_load lib/xarray.c:235 [inline]
 xa_load+0x122/0x2e0 lib/xarray.c:1463
 memcg_list_lru_allocated mm/list_lru.c:469 [inline]
 memcg_list_lru_alloc+0x13a/0xb10 mm/list_lru.c:483
 memcg_slab_pre_alloc_hook mm/slab.h:494 [inline]
 slab_pre_alloc_hook+0x2b2/0x310 mm/slab.h:715
 slab_alloc_node mm/slub.c:3279 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc_lru+0x49/0x2e0 mm/slub.c:3390
 __d_alloc+0x31/0x700 fs/dcache.c:1774
 d_alloc fs/dcache.c:1854 [inline]
 d_alloc_parallel+0xdc/0x1530 fs/dcache.c:2647
 __lookup_slow+0x134/0x3f0 fs/namei.c:1683
 lookup_one_len+0x19d/0x2d0 fs/namei.c:2748
 start_creating+0x184/0x310 fs/debugfs/inode.c:377
 __debugfs_create_file+0x6f/0x510 fs/debugfs/inode.c:422
 kvm_create_vm_debugfs+0x6da/0x980 virt/kvm/kvm_main.c:1104
 kvm_create_vm virt/kvm/kvm_main.c:1239 [inline]
 kvm_dev_ioctl_create_vm virt/kvm/kvm_main.c:5010 [inline]
 kvm_dev_ioctl+0x1404/0x1800 virt/kvm/kvm_main.c:5052
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdec779bf79
RSP: 002b:00007fdec85f7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdec7a15fa0 RCX: 00007fdec779bf79
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000008
RBP: 00007fdec78327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdec7a16038 R14: 00007fdec7a15fa0 R15: 00007ffeb0cd3728
 </TASK>
rcu: rcu_preempt kthread starved for 10378 jiffies! g130089 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:27736 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x303/0x1340 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x99/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/12 10:22 linux-6.1.y 8ce36b2849ef 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kvm_dev_ioctl
2026/01/10 12:34 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in kvm_dev_ioctl
* Struck through repros no longer work on HEAD.