From: Avi Kivity <avi@redhat.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
KVM list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/6] KVM MMU: fix kvm_mmu_zap_page() and its calling path
Date: Mon, 12 Apr 2010 15:49:21 +0300 [thread overview]
Message-ID: <4BC316D1.3030009@redhat.com> (raw)
In-Reply-To: <4BC310A0.3090005@cn.fujitsu.com>
On 04/12/2010 03:22 PM, Xiao Guangrong wrote:
>
>> But kvm_mmu_zap_page() will only destroy sp == tpos == pos; n points at
>> pos->next already, so it's safe.
>>
>>
> kvm_mmu_zap_page(sp) not only zaps sp but also zaps all sp's unsync children
> pages, if n is just sp's unsyc child, just at the same hlist and just behind sp,
> it will crash. :-)
>
Ouch. I see now, thanks for explaining.
One way to fix it is to make kvm_mmu_zap_page() only zap the page it is
given, and use sp->role.invalid on its children. But it's better to fix
it now quickly and do the more involved fixes later.
Just change the assignment to a 'goto restart;' please, I don't like
playing with list_for_each internals.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-04-12 12:49 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-12 7:59 [PATCH 1/6] KVM MMU: remove unused struct Xiao Guangrong
2010-04-12 8:01 ` [PATCH 2/6] KVM MMU: fix kvm_mmu_zap_page() and its calling path Xiao Guangrong
2010-04-12 8:24 ` Avi Kivity
2010-04-12 8:53 ` Xiao Guangrong
2010-04-12 9:08 ` Avi Kivity
2010-04-12 9:22 ` Xiao Guangrong
2010-04-12 10:25 ` Avi Kivity
2010-04-12 12:22 ` Xiao Guangrong
2010-04-12 12:49 ` Avi Kivity [this message]
2010-04-12 17:10 ` Marcelo Tosatti
2010-04-13 1:34 ` Xiao Guangrong
2010-04-13 14:59 ` Marcelo Tosatti
2010-04-14 2:14 ` Xiao Guangrong
2010-04-14 16:31 ` Marcelo Tosatti
2010-04-12 8:02 ` [PATCH 3/6] KVM MMU: optimize/cleanup for marking parent unsync Xiao Guangrong
2010-04-12 8:32 ` Avi Kivity
2010-04-12 8:55 ` Xiao Guangrong
2010-04-12 17:12 ` Marcelo Tosatti
2010-04-13 1:53 ` Xiao Guangrong
2010-04-13 11:58 ` Avi Kivity
2010-04-13 15:01 ` Marcelo Tosatti
2010-04-14 3:23 ` Xiao Guangrong
2010-04-14 3:58 ` Xiao Guangrong
2010-04-14 16:35 ` Marcelo Tosatti
2010-04-12 8:03 ` [PATCH 4/6] KVM MMU: optimize for writing cr4 Xiao Guangrong
2010-04-12 8:34 ` Avi Kivity
2010-04-12 10:42 ` Xiao Guangrong
2010-04-12 11:22 ` Avi Kivity
2010-04-13 3:07 ` Xiao Guangrong
2010-04-13 6:42 ` Avi Kivity
2010-04-12 8:05 ` [PATCH 5/6] KVM MMU: reduce kvm_mmu_page size Xiao Guangrong
2010-04-12 8:36 ` Avi Kivity
2010-04-12 11:11 ` Xiao Guangrong
2010-04-12 8:06 ` [PATCH 6/6] KVM MMU: optimize synchronization shadow pages Xiao Guangrong
2010-04-12 8:43 ` Avi Kivity
2010-04-12 11:14 ` Xiao Guangrong
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