From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: aarcange@redhat.com, linux-mm@kvack.org
Subject: Re: [PATCH] mm/THP: Use the right function when updating access flags
Date: Sun, 12 May 2013 14:07:26 +0530 [thread overview]
Message-ID: <87d2swoapl.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130508130454.8b0d87cfb9273227c9a9dabf@linux-foundation.org>
Andrew Morton <akpm@linux-foundation.org> writes:
> On Tue, 7 May 2013 02:19:48 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
>
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>>
>> We should use pmdp_set_access_flags to update access flags. Archs like powerpc
>> use extra checks(_PAGE_BUSY) when updating a hugepage PTE. A set_pmd_at doesn't
>> do those checks. We should use set_pmd_at only when updating a none hugepage PTE.
>>
>> ...
>>
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -1265,7 +1265,9 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
>> * young bit, instead of the current set_pmd_at.
>> */
>> _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
>> - set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
>> + if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
>> + pmd, _pmd, 1))
>> + update_mmu_cache_pmd(vma, addr, pmd);
>> }
>> if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
>> if (page->mapping && trylock_page(page)) {
>
> <canned message>
> When writing a changelog, please describe the end-user-visible effects
> of the bug, so that others can more easily decide which kernel
> version(s) should be fixed, and so that downstream kernel maintainers
> can more easily work out whether this patch will fix a problem which
> they or their customers are observing.
I found that reading code while debugging some crashes with THP on
ppc64. So user visible effects would mostly be some random crashes.
I will make sure to document the user visible effects next time.
-aneesh
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
prev parent reply other threads:[~2013-05-12 8:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-06 20:49 [PATCH] mm/THP: Use the right function when updating access flags Aneesh Kumar K.V
2013-05-08 20:04 ` Andrew Morton
2013-05-12 8:37 ` 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=87d2swoapl.fsf@linux.vnet.ibm.com \
--to=aneesh.kumar@linux.vnet.ibm.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-mm@kvack.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).