From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org,
Michael Neuling <mikey@neuling.org>,
paulus@samba.org, dwg@au1.ibm.com
Subject: Re: [PATCH 1/2] powerpc: use smp_rmb when looking at deposisted pgtable to store hash index
Date: Mon, 20 May 2013 14:56:18 +0530 [thread overview]
Message-ID: <87a9nq57et.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1369031318.6387.1.camel@pasglop>
Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> On Mon, 2013-05-20 at 09:57 +0530, Aneesh Kumar K.V wrote:
>> Michael Neuling <mikey@neuling.org> writes:
>>
>> > Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:
>> >
>> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> >>
>> >> We need to use smb_rmb when looking at hpte slot array. Otherwise we could
>> >> reorder the hpte_slot array load bfore even we marked the pmd trans huge.
>> >
>> > Does this need to go back into the stable series?
>> >
>>
>> No the changes are not yet upstream. hpte_slot_array changes are in the
>> THP series. I didn't want to post the entire series again with the
>> above two patches.
>
> Note that any patch that adds such a rmb should have a very clear
> description of what is the corresponding wmb. It's almost never right to
> have one without the other. IE. What is it that you are ordering
> against.
Will update the commit message. Some of that smb_wmb() are in the
core THP, and the others in ppc64 code. Will update with more info.
When we deposit pgtable we use pgtable_trans_huge_deposit that calls
related smb_wmb(). When we read pgtable via pgtable_trans_huge_withdraw,
core THP code does the related smb_wmb() after setting the right
PTE information in the pgtable.
-aneesh
prev parent reply other threads:[~2013-05-20 9:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-17 8:15 [PATCH 1/2] powerpc: use smp_rmb when looking at deposisted pgtable to store hash index Aneesh Kumar K.V
2013-05-17 8:15 ` [PATCH 2/2] powerpc: split hugepage when using subpage protection Aneesh Kumar K.V
2013-05-17 8:36 ` Aneesh Kumar K.V
2013-05-20 1:18 ` [PATCH 1/2] powerpc: use smp_rmb when looking at deposisted pgtable to store hash index Michael Neuling
2013-05-20 4:27 ` Aneesh Kumar K.V
2013-05-20 6:28 ` Benjamin Herrenschmidt
2013-05-20 9:26 ` Aneesh Kumar K.V [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87a9nq57et.fsf@linux.vnet.ibm.com \
--to=aneesh.kumar@linux.vnet.ibm.com \
--cc=benh@kernel.crashing.org \
--cc=dwg@au1.ibm.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mikey@neuling.org \
--cc=paulus@samba.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).