Re: [PATCH] mm/autonuma: don't use set_pte_at when updating protnone ptes

From	Andrew Morton <akpm@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm/autonuma: don't use set_pte_at when updating protnone ptes
Date	2017-02-15 01:10 +0100
Message-ID	<taVkt-mH-3@gated-at.bofh.it> (permalink)
References	<t7UXE-7LS-31@gated-at.bofh.it> <taM7v-2Vs-3@gated-at.bofh.it>
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On Tue, 14 Feb 2017 19:41:17 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:

> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
> 
> > Architectures like ppc64, use privilege access bit to mark pte non accessible.
> > This implies that kernel can do a copy_to_user to an address marked for numa fault.
> > This also implies that there can be a parallel hardware update for the pte.
> > set_pte_at cannot be used in such scenarios. Hence switch the pte
> > update to use ptep_get_and_clear and set_pte_at combination.
> >
> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> 
> With this and other patches a kvm guest is giving me
> 
> ...
> 
> Reverting this patch gets rid of the above hang. But I am running into segfault
> with systemd in guest. It could be some other patches in my local tree.
> 
> Maybe we should hold merging this to 4.11 and wait for this to get more
> testing ?

Shall do.  Please let me know the outcome...

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Re: [PATCH] mm/autonuma: don't use set_pte_at when updating protnone ptes "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2017-02-14 15:20 +0100
  Re: [PATCH] mm/autonuma: don't use set_pte_at when updating  protnone ptes Andrew Morton <akpm@linux-foundation.org> - 2017-02-15 01:10 +0100

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