From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
To: kvm-ia64@vger.kernel.org
Subject: Re: [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows
Date: Tue, 13 Apr 2010 07:03:52 +0000 [thread overview]
Message-ID: <4BC41758.4000008@oss.ntt.co.jp> (raw)
In-Reply-To: <20100412193535.6c502695.yoshikawa.takuya@oss.ntt.co.jp>
>>
>> BTW, just from my curiosity, are there any cases in which we use such
>> huge
>> number of pages currently?
>>
>> ALIGN(memslot->npages, BITS_PER_LONG) / 8;
>>
>> More than G pages need really big memory!
>> -- We are assuming some special cases like "short" int size?
>
> No, int is 32 bits, but memslot->npages is not our under control.
>
> Note that you don't actually need all those pages to create a large
> memory slot.
>
>>
>> If so, we may have to care about a lot of things from now on, because
>> common
>> functions like __set_bit() don't support such long buffers.
>
> It's better to limit memory slots to something that can be handled by
> everything, then. 2^31 pages is plenty. Return -EINVAL if the slot is
> too large.
I agree with that, so we make this patch pending to fix like that?
-- or should make a new patch based on this patch?
>
>
WARNING: multiple messages have this Message-ID (diff)
From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, kvm-ia64@vger.kernel.org,
kvm-ppc@vger.kernel.org
Subject: Re: [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows
Date: Tue, 13 Apr 2010 07:03:52 +0000 [thread overview]
Message-ID: <4BC41758.4000008@oss.ntt.co.jp> (raw)
In-Reply-To: <4BC4142C.8050400@redhat.com>
>>
>> BTW, just from my curiosity, are there any cases in which we use such
>> huge
>> number of pages currently?
>>
>> ALIGN(memslot->npages, BITS_PER_LONG) / 8;
>>
>> More than G pages need really big memory!
>> -- We are assuming some special cases like "short" int size?
>
> No, int is 32 bits, but memslot->npages is not our under control.
>
> Note that you don't actually need all those pages to create a large
> memory slot.
>
>>
>> If so, we may have to care about a lot of things from now on, because
>> common
>> functions like __set_bit() don't support such long buffers.
>
> It's better to limit memory slots to something that can be handled by
> everything, then. 2^31 pages is plenty. Return -EINVAL if the slot is
> too large.
I agree with that, so we make this patch pending to fix like that?
-- or should make a new patch based on this patch?
>
>
WARNING: multiple messages have this Message-ID (diff)
From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, kvm-ia64@vger.kernel.org,
kvm-ppc@vger.kernel.org
Subject: Re: [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows
Date: Tue, 13 Apr 2010 16:03:52 +0900 [thread overview]
Message-ID: <4BC41758.4000008@oss.ntt.co.jp> (raw)
In-Reply-To: <4BC4142C.8050400@redhat.com>
>>
>> BTW, just from my curiosity, are there any cases in which we use such
>> huge
>> number of pages currently?
>>
>> ALIGN(memslot->npages, BITS_PER_LONG) / 8;
>>
>> More than G pages need really big memory!
>> -- We are assuming some special cases like "short" int size?
>
> No, int is 32 bits, but memslot->npages is not our under control.
>
> Note that you don't actually need all those pages to create a large
> memory slot.
>
>>
>> If so, we may have to care about a lot of things from now on, because
>> common
>> functions like __set_bit() don't support such long buffers.
>
> It's better to limit memory slots to something that can be handled by
> everything, then. 2^31 pages is plenty. Return -EINVAL if the slot is
> too large.
I agree with that, so we make this patch pending to fix like that?
-- or should make a new patch based on this patch?
>
>
next prev parent reply other threads:[~2010-04-13 7:03 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-12 10:35 [PATCH] KVM: fix the handling of dirty bitmaps to avoid overflows Takuya Yoshikawa
2010-04-12 10:35 ` Takuya Yoshikawa
2010-04-12 10:35 ` Takuya Yoshikawa
2010-04-12 11:10 ` Alexander Graf
2010-04-12 11:10 ` Alexander Graf
2010-04-12 11:10 ` Alexander Graf
2010-04-12 17:39 ` Marcelo Tosatti
2010-04-12 17:39 ` Marcelo Tosatti
2010-04-12 17:39 ` Marcelo Tosatti
2010-04-13 0:52 ` Takuya Yoshikawa
2010-04-13 0:52 ` Takuya Yoshikawa
2010-04-13 0:52 ` Takuya Yoshikawa
2010-04-13 6:50 ` Avi Kivity
2010-04-13 6:50 ` Avi Kivity
2010-04-13 6:50 ` Avi Kivity
2010-04-13 7:03 ` Takuya Yoshikawa [this message]
2010-04-13 7:03 ` Takuya Yoshikawa
2010-04-13 7:03 ` Takuya Yoshikawa
2010-04-13 7:05 ` Avi Kivity
2010-04-13 7:05 ` Avi Kivity
2010-04-13 7:05 ` Avi Kivity
2010-04-13 13:47 ` [PATCH] KVM: cleanup: limit the number of pages per memory slot Takuya Yoshikawa
2010-04-14 16:58 ` Marcelo Tosatti
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