Re: [PATCH] x86_64 add NX mask for PTE entry

From: bibo,mao
Date: Wed Oct 18 2006 - 07:46:28 EST


Also I think change_page_attr is buggy. if orginal page is not
large page, when that page's previous attr is reverted revert_page()
function will be called to make that page huge. Indeed I think
there is no need to do this.

thanks
bibo,mao

bibo,mao wrote:
Andi Kleen wrote:
On Wednesday 18 October 2006 11:15, bibo,mao wrote:
Hi,
If function change_page_attr_addr calls revert_page to revert
to original pte value, mk_pte_phys does not mask NX bit. If NX bit
is set on no NX hardware supported x86_64 machine, there is will
be RSVD type page fault and system will crash. This patch adds NX
mask bit for PTE entry.

Hmm, weird. I wonder why that didn't trip up earlier. Did you
actually see that happening?
I remember previous system worked well on 2.6.12 and 2.6.13 version,
but recently even on older kernel(2.6.9) there will be many times of
page fault error and system crashes at last when rebooting system.

I will paste the oops message tomorrow.

thanks
bibo,mao


-Andi
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