| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
[Xen-devel] Re: One (possible) x86 get_user_pages bug
|
To: |
Jan Beulich <JBeulich@xxxxxxxxxx> |
|
Subject: |
[Xen-devel] Re: One (possible) x86 get_user_pages bug |
|
From: |
Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> |
|
Date: |
Thu, 27 Jan 2011 17:56:43 +0100 |
|
Cc: |
Kaushik Barde <kbarde@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Kenneth Lee <liguozhu@xxxxxxxxxx>, Nick Piggin <npiggin@xxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, wangzhenguo@xxxxxxxxxx, Xiaowei Yang <xiaowei.yang@xxxxxxxxxx>, linqaingmin <linqiangmin@xxxxxxxxxx>, fanhenglong@xxxxxxxxxx, Wu Fengguang <fengguang.wu@xxxxxxxxx> |
|
Delivery-date: |
Thu, 27 Jan 2011 18:55:38 -0800 |
|
Envelope-to: |
www-data@xxxxxxxxxxxxxxxxxxx |
|
In-reply-to: |
<4D41A651020000780002ED36@xxxxxxxxxxxxxxxxxx> |
|
List-help: |
<mailto:xen-devel-request@lists.xensource.com?subject=help> |
|
List-id: |
Xen developer discussion <xen-devel.lists.xensource.com> |
|
List-post: |
<mailto:xen-devel@lists.xensource.com> |
|
List-subscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
|
List-unsubscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
|
References: |
<4D416D9A.9010603@xxxxxxxxxx> <4D41A651020000780002ED36@xxxxxxxxxxxxxxxxxx> |
|
Sender: |
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
On Thu, 2011-01-27 at 16:07 +0000, Jan Beulich wrote:
>
> Nick, based on your doing of the initial implementation, would
> you be able to estimate whether disabling get_user_pages_fast()
> altogether for Xen would be performing measurably worse than
> adding the locks (but continuing to avoid acquiring mm->mmap_sem)
> as suggested by Xiaowei? That's of course only if the latter is correct
> at all, of which I haven't fully convinced myself yet.
Also, I don't think taking the pte_lock is sufficient in your case..
since x86 mmu_gather frees the page tables themselves too, your
dereference of the pgd/pud/pmd will be subject to the same deref after
free problems.
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home