2011-05-11 00:28:34

by OGAWA Hirofumi

Subject: [PATCH] kvm: Fix kvm mmu_notifier initialization order

Like the following, mmu_notifier can be called after registering
immediately. So, kvm have to initialize kvm->mmu_lock before it.

BUG: spinlock bad magic on CPU#0, kswapd0/342
lock: ffff8800af8c4000, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
Pid: 342, comm: kswapd0 Not tainted 2.6.39-rc5+ #1
Call Trace:
[<ffffffff8118ce61>] spin_bug+0x9c/0xa3
[<ffffffff8118ce91>] do_raw_spin_lock+0x29/0x13c
[<ffffffff81024923>] ? flush_tlb_others_ipi+0xaf/0xfd
[<ffffffff812e22f3>] _raw_spin_lock+0x9/0xb
[<ffffffffa0582325>] kvm_mmu_notifier_clear_flush_young+0x2c/0x66 [kvm]
[<ffffffff810d3ff3>] __mmu_notifier_clear_flush_young+0x2b/0x57
[<ffffffff810c8761>] page_referenced_one+0x88/0xea
[<ffffffff810c89bf>] page_referenced+0x1fc/0x256
[<ffffffff810b2771>] shrink_page_list+0x187/0x53a
[<ffffffff810b2ed7>] shrink_inactive_list+0x1e0/0x33d
[<ffffffff810acf95>] ? determine_dirtyable_memory+0x15/0x27
[<ffffffff812e90ee>] ? call_function_single_interrupt+0xe/0x20
[<ffffffff810b3356>] shrink_zone+0x322/0x3de
[<ffffffff810a9587>] ? zone_watermark_ok_safe+0xe2/0xf1
[<ffffffff810b3928>] kswapd+0x516/0x818
[<ffffffff810b3412>] ? shrink_zone+0x3de/0x3de
[<ffffffff81053d17>] kthread+0x7d/0x85
[<ffffffff812e9394>] kernel_thread_helper+0x4/0x10
[<ffffffff81053c9a>] ? __init_kthread_worker+0x37/0x37
[<ffffffff812e9390>] ? gs_change+0xb/0xb

Signed-off-by: OGAWA Hirofumi <[email protected]>
---

virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN virt/kvm/kvm_main.c~kvm-mmu_notifier-lock-fix virt/kvm/kvm_main.c
--- linux-2.6/virt/kvm/kvm_main.c~kvm-mmu_notifier-lock-fix 2011-05-11 09:21:52.000000000 +0900
+++ linux-2.6-hirofumi/virt/kvm/kvm_main.c 2011-05-11 09:22:04.000000000 +0900
@@ -467,6 +467,7 @@ static struct kvm *kvm_create_vm(void)
if (!kvm->buses[i])
goto out_err;
}
+ spin_lock_init(&kvm->mmu_lock);

r = kvm_init_mmu_notifier(kvm);
if (r)
@@ -474,7 +475,6 @@ static struct kvm *kvm_create_vm(void)

kvm->mm = current->mm;
atomic_inc(&kvm->mm->mm_count);
- spin_lock_init(&kvm->mmu_lock);
kvm_eventfd_init(kvm);
mutex_init(&kvm->lock);
mutex_init(&kvm->irq_lock);
_

--
OGAWA Hirofumi <[email protected]>

2011-05-11 15:57:56

by Avi Kivity

Subject: Re: [PATCH] kvm: Fix kvm mmu_notifier initialization order

On 05/11/2011 03:28 AM, OGAWA Hirofumi wrote:
> Like the following, mmu_notifier can be called after registering
> immediately. So, kvm have to initialize kvm->mmu_lock before it.
>
> BUG: spinlock bad magic on CPU#0, kswapd0/342
> lock: ffff8800af8c4000, .magic: 00000000, .owner:<none>/-1, .owner_cpu: 0
> Pid: 342, comm: kswapd0 Not tainted 2.6.39-rc5+ #1
> Call Trace:
> [<ffffffff8118ce61>] spin_bug+0x9c/0xa3
> [<ffffffff8118ce91>] do_raw_spin_lock+0x29/0x13c
> [<ffffffff81024923>] ? flush_tlb_others_ipi+0xaf/0xfd
> [<ffffffff812e22f3>] _raw_spin_lock+0x9/0xb
> [<ffffffffa0582325>] kvm_mmu_notifier_clear_flush_young+0x2c/0x66 [kvm]
> [<ffffffff810d3ff3>] __mmu_notifier_clear_flush_young+0x2b/0x57
> [<ffffffff810c8761>] page_referenced_one+0x88/0xea
> [<ffffffff810c89bf>] page_referenced+0x1fc/0x256
> [<ffffffff810b2771>] shrink_page_list+0x187/0x53a
> [<ffffffff810b2ed7>] shrink_inactive_list+0x1e0/0x33d
> [<ffffffff810acf95>] ? determine_dirtyable_memory+0x15/0x27
> [<ffffffff812e90ee>] ? call_function_single_interrupt+0xe/0x20
> [<ffffffff810b3356>] shrink_zone+0x322/0x3de
> [<ffffffff810a9587>] ? zone_watermark_ok_safe+0xe2/0xf1
> [<ffffffff810b3928>] kswapd+0x516/0x818
> [<ffffffff810b3412>] ? shrink_zone+0x3de/0x3de
> [<ffffffff81053d17>] kthread+0x7d/0x85
> [<ffffffff812e9394>] kernel_thread_helper+0x4/0x10
> [<ffffffff81053c9a>] ? __init_kthread_worker+0x37/0x37
> [<ffffffff812e9390>] ? gs_change+0xb/0xb
>

Applied, thanks.

--
error compiling committee.c: too many arguments to function