* [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4)
@ 2026-08-20 13:16 syzbot
2026-08-20 16:29 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2026-08-20 13:16 UTC (permalink / raw)
To: akpm, brendan.jackman, hannes, linux-kernel, linux-mm, mhocko,
surenb, syzkaller-bugs, vbabka, ziy
Hello,
syzbot found the following issue on:
HEAD commit: e8bf40d15402 Merge tag 'chrome-platform-firmware-v7.3' of ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1434f815580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1941312e3e971b07
dashboard link: https://syzkaller.appspot.com/bug?extid=5f0b6e2e4195c75b5658
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7df7b958efe0/disk-e8bf40d1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cefbf90e524a/vmlinux-e8bf40d1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/37a530b91001/bzImage-e8bf40d1.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5f0b6e2e4195c75b5658@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P21500/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=207513, q=1145 ncpus=2)
task:syz.9.4605 state:R running task stack:26920 pid:21500 tgid:21500 ppid:14397 task_flags:0x40044c flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d4/0x5630 kernel/sched/core.c:7239
preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7561
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x14f/0x910 kernel/entry/common.c:167
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x222/0x350 kernel/locking/lockdep.c:5890
Code: ff ff ff e8 c0 0b 32 0a f7 44 24 08 00 02 00 00 0f 84 39 ff ff ff 65 48 8b 05 12 77 cb 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 57 a1 b8
RSP: 0018:ffffc900074cf260 EFLAGS: 00000286
RAX: 7db047bb98fc4c00 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 00000000c0065176 RSI: ffffffff8e4b5735 RDI: ffffffff8c4bdd80
RBP: ffffffff8177710f R08: ffffffff8177710f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb5a0e0 R12: 0000000000000002
R13: ffffffff8eb5a0e0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
save_stack+0x122/0x230 mm/page_owner.c:165
__reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc22/0xd20 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5741
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_noprof+0x315/0x720 mm/slub.c:5359
_kmalloc_noprof include/linux/slab.h:992 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
kobject_uevent_env+0x29e/0x9e0 lib/kobject_uevent.c:548
kvm_uevent_notify_change+0x300/0x3a0 virt/kvm/kvm_main.c:6335
kvm_destroy_vm virt/kvm/kvm_main.c:1260 [inline]
kvm_put_kvm+0xa9/0xb50 virt/kvm/kvm_main.c:1331
kvm_vm_release+0x43/0x50 virt/kvm/kvm_main.c:1354
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x73a/0x2360 kernel/exit.c:1009
do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
get_signal+0x121b/0x12c0 kernel/signal.c:3046
arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3a1f5e90e
RSP: 002b:00007fe3a2e23f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007fe3a2e246c0 RCX: 00007fe3a1f5e90e
RDX: 00007fe3a2e23fb0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe3a2035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe3a2226308 R14: 00007fe3a2226270 R15: 00007fe3a234fa48
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4)
2026-08-20 13:16 [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4) syzbot
@ 2026-08-20 16:29 ` Andrew Morton
2026-08-21 1:06 ` Ye Liu
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2026-08-20 16:29 UTC (permalink / raw)
To: syzbot
Cc: brendan.jackman, hannes, linux-kernel, linux-mm, mhocko, surenb,
syzkaller-bugs, vbabka, ziy, Zhen Ni, Ye Liu, Oscar Salvador,
Andrey Ryabinin, Alexander Potapenko, Andrey Konovalov,
Dmitry Vyukov
On Thu, 20 Aug 2026 06:16:25 -0700 syzbot <syzbot+5f0b6e2e4195c75b5658@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: e8bf40d15402 Merge tag 'chrome-platform-firmware-v7.3' of ..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1434f815580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=1941312e3e971b07
> dashboard link: https://syzkaller.appspot.com/bug?extid=5f0b6e2e4195c75b5658
> compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/7df7b958efe0/disk-e8bf40d1.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cefbf90e524a/vmlinux-e8bf40d1.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/37a530b91001/bzImage-e8bf40d1.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5f0b6e2e4195c75b5658@syzkaller.appspotmail.com
>
> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
> rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P21500/1:b..l
> rcu: (detected by 0, t=10503 jiffies, g=207513, q=1145 ncpus=2)
> task:syz.9.4605 state:R running task stack:26920 pid:21500 tgid:21500 ppid:14397 task_flags:0x40044c flags:0x00080003
Thanks.
lazybutt pasted this into Gemini:
https://share.gemini.google/9rAubqC4qNzf
: The combination of debug tools: KASAN quarantine processing + ORC
: unwinder + page_owner stack tracing executed so slowly on the CPU that
: it exceeded the RCU stall threshold.
(I think we've recently seen the same thing, different callers)
I can't say I'm terribly motivated. page_owner is expensive and if you
run heavy stress testing with page_owner enabled then such things
aren't surprising.
Let me Cc a few page_owner and KASAN people, see if they feel
differently.
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5510 [inline]
> __schedule+0x17d4/0x5630 kernel/sched/core.c:7239
> preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7561
> irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
> irqentry_exit+0x14f/0x910 kernel/entry/common.c:167
> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
> RIP: 0010:lock_acquire+0x222/0x350 kernel/locking/lockdep.c:5890
> Code: ff ff ff e8 c0 0b 32 0a f7 44 24 08 00 02 00 00 0f 84 39 ff ff ff 65 48 8b 05 12 77 cb 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 57 a1 b8
> RSP: 0018:ffffc900074cf260 EFLAGS: 00000286
> RAX: 7db047bb98fc4c00 RBX: 0000000000000000 RCX: 0000000000000046
> RDX: 00000000c0065176 RSI: ffffffff8e4b5735 RDI: ffffffff8c4bdd80
> RBP: ffffffff8177710f R08: ffffffff8177710f R09: 0000000000000000
> R10: 0000000000000000 R11: ffffffff8eb5a0e0 R12: 0000000000000002
> R13: ffffffff8eb5a0e0 R14: 0000000000000000 R15: 0000000000000246
> rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
> rcu_read_lock include/linux/rcupdate.h:840 [inline]
> class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
> unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
> arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
> stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
> save_stack+0x122/0x230 mm/page_owner.c:165
> __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
> reset_page_owner include/linux/page_owner.h:25 [inline]
> __free_pages_prepare mm/page_alloc.c:1406 [inline]
> __free_frozen_pages+0xc22/0xd20 mm/page_alloc.c:2950
> __slab_free+0x274/0x2c0 mm/slub.c:5741
> qlink_free mm/kasan/quarantine.c:163 [inline]
> qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
> kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
> __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
> kasan_slab_alloc include/linux/kasan.h:253 [inline]
> slab_post_alloc_hook mm/slub.c:4584 [inline]
> slab_alloc_node mm/slub.c:4917 [inline]
> __do_kmalloc_node mm/slub.c:5333 [inline]
> __kmalloc_noprof+0x315/0x720 mm/slub.c:5359
> _kmalloc_noprof include/linux/slab.h:992 [inline]
> _kzalloc_noprof include/linux/slab.h:1309 [inline]
> kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
> kobject_uevent_env+0x29e/0x9e0 lib/kobject_uevent.c:548
> kvm_uevent_notify_change+0x300/0x3a0 virt/kvm/kvm_main.c:6335
> kvm_destroy_vm virt/kvm/kvm_main.c:1260 [inline]
> kvm_put_kvm+0xa9/0xb50 virt/kvm/kvm_main.c:1331
> kvm_vm_release+0x43/0x50 virt/kvm/kvm_main.c:1354
> __fput+0x418/0xa50 fs/file_table.c:512
> task_work_run+0x1d9/0x270 kernel/task_work.c:233
> exit_task_work include/linux/task_work.h:40 [inline]
> do_exit+0x73a/0x2360 kernel/exit.c:1009
> do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
> get_signal+0x121b/0x12c0 kernel/signal.c:3046
> arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
> __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
> exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
> __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
> syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
> syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
> do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fe3a1f5e90e
> RSP: 002b:00007fe3a2e23f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
> RAX: fffffffffffffdfc RBX: 00007fe3a2e246c0 RCX: 00007fe3a1f5e90e
> RDX: 00007fe3a2e23fb0 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 00007fe3a2035024 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fe3a2226308 R14: 00007fe3a2226270 R15: 00007fe3a234fa48
> </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4)
2026-08-20 16:29 ` Andrew Morton
@ 2026-08-21 1:06 ` Ye Liu
2026-08-21 1:20 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Ye Liu @ 2026-08-21 1:06 UTC (permalink / raw)
To: Andrew Morton, syzbot
Cc: brendan.jackman, hannes, linux-kernel, linux-mm, mhocko, surenb,
syzkaller-bugs, vbabka, ziy, Zhen Ni, Oscar Salvador,
Andrey Ryabinin, Alexander Potapenko, Andrey Konovalov,
Dmitry Vyukov
在 2026/8/21 00:29, Andrew Morton 写道:
> On Thu, 20 Aug 2026 06:16:25 -0700 syzbot <syzbot+5f0b6e2e4195c75b5658@syzkaller.appspotmail.com> wrote:
>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: e8bf40d15402 Merge tag 'chrome-platform-firmware-v7.3' of ..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1434f815580000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=1941312e3e971b07
>> dashboard link: https://syzkaller.appspot.com/bug?extid=5f0b6e2e4195c75b5658
>> compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/7df7b958efe0/disk-e8bf40d1.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/cefbf90e524a/vmlinux-e8bf40d1.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/37a530b91001/bzImage-e8bf40d1.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+5f0b6e2e4195c75b5658@syzkaller.appspotmail.com
>>
>> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
>> rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P21500/1:b..l
>> rcu: (detected by 0, t=10503 jiffies, g=207513, q=1145 ncpus=2)
>> task:syz.9.4605 state:R running task stack:26920 pid:21500 tgid:21500 ppid:14397 task_flags:0x40044c flags:0x00080003
>
> Thanks.
>
> lazybutt pasted this into Gemini:
> https://share.gemini.google/9rAubqC4qNzf
>
> : The combination of debug tools: KASAN quarantine processing + ORC
> : unwinder + page_owner stack tracing executed so slowly on the CPU that
> : it exceeded the RCU stall threshold.
>
> (I think we've recently seen the same thing, different callers)
>
> I can't say I'm terribly motivated. page_owner is expensive and if you
> run heavy stress testing with page_owner enabled then such things
> aren't surprising.
>
> Let me Cc a few page_owner and KASAN people, see if they feel
> differently.
Adding cond_resched() to the qlist_free_all() loop would fix this .
kasan_quarantine_remove_cache() already dose the same in its scanning loop.
>
>> Call Trace:
>> <TASK>
>> context_switch kernel/sched/core.c:5510 [inline]
>> __schedule+0x17d4/0x5630 kernel/sched/core.c:7239
>> preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7561
>> irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
>> irqentry_exit+0x14f/0x910 kernel/entry/common.c:167
>> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
>> RIP: 0010:lock_acquire+0x222/0x350 kernel/locking/lockdep.c:5890
>> Code: ff ff ff e8 c0 0b 32 0a f7 44 24 08 00 02 00 00 0f 84 39 ff ff ff 65 48 8b 05 12 77 cb 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 57 a1 b8
>> RSP: 0018:ffffc900074cf260 EFLAGS: 00000286
>> RAX: 7db047bb98fc4c00 RBX: 0000000000000000 RCX: 0000000000000046
>> RDX: 00000000c0065176 RSI: ffffffff8e4b5735 RDI: ffffffff8c4bdd80
>> RBP: ffffffff8177710f R08: ffffffff8177710f R09: 0000000000000000
>> R10: 0000000000000000 R11: ffffffff8eb5a0e0 R12: 0000000000000002
>> R13: ffffffff8eb5a0e0 R14: 0000000000000000 R15: 0000000000000246
>> rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
>> rcu_read_lock include/linux/rcupdate.h:840 [inline]
>> class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
>> unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
>> arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
>> stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
>> save_stack+0x122/0x230 mm/page_owner.c:165
>> __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
>> reset_page_owner include/linux/page_owner.h:25 [inline]
>> __free_pages_prepare mm/page_alloc.c:1406 [inline]
>> __free_frozen_pages+0xc22/0xd20 mm/page_alloc.c:2950
>> __slab_free+0x274/0x2c0 mm/slub.c:5741
>> qlink_free mm/kasan/quarantine.c:163 [inline]
>> qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
>> kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
>> __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
>> kasan_slab_alloc include/linux/kasan.h:253 [inline]
>> slab_post_alloc_hook mm/slub.c:4584 [inline]
>> slab_alloc_node mm/slub.c:4917 [inline]
>> __do_kmalloc_node mm/slub.c:5333 [inline]
>> __kmalloc_noprof+0x315/0x720 mm/slub.c:5359
>> _kmalloc_noprof include/linux/slab.h:992 [inline]
>> _kzalloc_noprof include/linux/slab.h:1309 [inline]
>> kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
>> kobject_uevent_env+0x29e/0x9e0 lib/kobject_uevent.c:548
>> kvm_uevent_notify_change+0x300/0x3a0 virt/kvm/kvm_main.c:6335
>> kvm_destroy_vm virt/kvm/kvm_main.c:1260 [inline]
>> kvm_put_kvm+0xa9/0xb50 virt/kvm/kvm_main.c:1331
>> kvm_vm_release+0x43/0x50 virt/kvm/kvm_main.c:1354
>> __fput+0x418/0xa50 fs/file_table.c:512
>> task_work_run+0x1d9/0x270 kernel/task_work.c:233
>> exit_task_work include/linux/task_work.h:40 [inline]
>> do_exit+0x73a/0x2360 kernel/exit.c:1009
>> do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
>> get_signal+0x121b/0x12c0 kernel/signal.c:3046
>> arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
>> __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
>> exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
>> __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
>> syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
>> syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
>> do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
>> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7fe3a1f5e90e
>> RSP: 002b:00007fe3a2e23f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
>> RAX: fffffffffffffdfc RBX: 00007fe3a2e246c0 RCX: 00007fe3a1f5e90e
>> RDX: 00007fe3a2e23fb0 RSI: 0000000000000000 RDI: 0000000000000000
>> RBP: 00007fe3a2035024 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007fe3a2226308 R14: 00007fe3a2226270 R15: 00007fe3a234fa48
>> </TASK>
>>
>>
>> ---
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--
Thanks,
Ye Liu
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4)
2026-08-21 1:06 ` Ye Liu
@ 2026-08-21 1:20 ` Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2026-08-21 1:20 UTC (permalink / raw)
To: Ye Liu
Cc: syzbot, brendan.jackman, hannes, linux-kernel, linux-mm, mhocko,
surenb, syzkaller-bugs, vbabka, ziy, Zhen Ni, Oscar Salvador,
Andrey Ryabinin, Alexander Potapenko, Andrey Konovalov,
Dmitry Vyukov
On Fri, 21 Aug 2026 09:06:48 +0800 Ye Liu <ye.liu@linux.dev> wrote:
> > : The combination of debug tools: KASAN quarantine processing + ORC
> > : unwinder + page_owner stack tracing executed so slowly on the CPU that
> > : it exceeded the RCU stall threshold.
> >
> > (I think we've recently seen the same thing, different callers)
> >
> > I can't say I'm terribly motivated. page_owner is expensive and if you
> > run heavy stress testing with page_owner enabled then such things
> > aren't surprising.
> >
> > Let me Cc a few page_owner and KASAN people, see if they feel
> > differently.
>
> Adding cond_resched() to the qlist_free_all() loop would fix this .
> kasan_quarantine_remove_cache() already dose the same in its scanning loop.
I don't think cond_resched() does what we want for RCU stalls.
And cond_resched() is a no-op without CONFIG_PREEMPT_NONE, which wasn't
set here.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-08-21 1:20 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-08-20 13:16 [syzbot] [mm?] INFO: rcu detected stall in kvm_vm_release (4) syzbot
2026-08-20 16:29 ` Andrew Morton
2026-08-21 1:06 ` Ye Liu
2026-08-21 1:20 ` Andrew Morton
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