From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Hugh Dickins <hughd@google.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Pavel Emelyanov <xemul@parallels.com>,
"Zi Yan" <zi.yan@cs.rutgers.edu>,
Balbir Singh <bsingharora@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Naoya Horiguchi" <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v2 01/12] mm: x86: move _PAGE_SWP_SOFT_DIRTY from bit 7 to bit 6
Date: Fri, 11 Nov 2016 01:08:36 +0000 [thread overview]
Message-ID: <20161111010834.GA28679@hori1.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <534caa72-c109-9716-15d2-5e80f4038f8d@intel.com>
On Thu, Nov 10, 2016 at 03:29:51PM -0800, Dave Hansen wrote:
> On 11/07/2016 03:31 PM, Naoya Horiguchi wrote:
> > pmd_present() checks _PAGE_PSE along with _PAGE_PRESENT to avoid false negative
> > return when it races with thp spilt (during which _PAGE_PRESENT is temporary
> > cleared.) I don't think that dropping _PAGE_PSE check in pmd_present() works
> > well because it can hurt optimization of tlb handling in thp split.
> > In the current kernel, bit 6 is not used in non-present format because nonlinear
> > file mapping is obsolete, so let's move _PAGE_SWP_SOFT_DIRTY to that bit.
> > Bit 7 is used as reserved (always clear), so please don't use it for other
> > purpose.
> ...
> > #ifdef CONFIG_MEM_SOFT_DIRTY
> > -#define _PAGE_SWP_SOFT_DIRTY _PAGE_PSE
> > +#define _PAGE_SWP_SOFT_DIRTY _PAGE_DIRTY
> > #else
> > #define _PAGE_SWP_SOFT_DIRTY (_AT(pteval_t, 0))
> > #endif
>
> I'm not sure this works. Take a look at commit 00839ee3b29 and the
> erratum it works around. I _think_ this means that a system affected by
> the erratum might see an erroneous _PAGE_SWP_SOFT_DIRTY/_PAGE_DIRTY get
> set in swap ptes.
>
> There are much worse things that can happen, but I don't think bits 5
> (Accessed) and 6 (Dirty) are good choices since they're affected by the
> erratum.
Thank you for the information. According to 00839ee3b29, some bits which
are safe from the errata are reclaimed, so assigning one of such bits for
_PAGE_SWP_SOFT_DIRTY seems to work. And I'll update the description.
Thanks,
Naoya Horiguchi
next prev parent reply other threads:[~2016-11-11 1:09 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-07 23:31 [PATCH v2 00/12] mm: page migration enhancement for thp Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 01/12] mm: x86: move _PAGE_SWP_SOFT_DIRTY from bit 7 to bit 6 Naoya Horiguchi
2016-11-10 23:29 ` Dave Hansen
2016-11-11 1:08 ` Naoya Horiguchi [this message]
2016-11-11 11:12 ` Kirill A. Shutemov
2016-11-07 23:31 ` [PATCH v2 02/12] mm: mempolicy: add queue_pages_node_check() Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 03/12] mm: thp: introduce separate TTU flag for thp freezing Naoya Horiguchi
2016-11-10 8:31 ` Anshuman Khandual
2016-11-10 9:09 ` Naoya Horiguchi
2016-11-11 3:18 ` Anshuman Khandual
2016-11-11 11:16 ` Kirill A. Shutemov
2016-11-07 23:31 ` [PATCH v2 04/12] mm: thp: introduce CONFIG_ARCH_ENABLE_THP_MIGRATION Naoya Horiguchi
2016-11-11 11:18 ` Kirill A. Shutemov
2016-11-15 2:05 ` Naoya Horiguchi
2016-11-28 14:21 ` Michal Hocko
2016-11-29 7:50 ` Naoya Horiguchi
2016-11-29 8:45 ` Michal Hocko
2016-11-07 23:31 ` [PATCH v2 05/12] mm: thp: add core routines for thp/pmd migration Naoya Horiguchi
2016-11-08 3:05 ` kbuild test robot
2016-11-08 6:46 ` Naoya Horiguchi
2016-11-08 8:13 ` Anshuman Khandual
2016-11-08 8:16 ` Naoya Horiguchi
2016-11-10 8:29 ` Anshuman Khandual
2016-11-10 9:43 ` Naoya Horiguchi
2016-11-14 11:45 ` Kirill A. Shutemov
2016-11-15 4:57 ` Naoya Horiguchi
2016-11-28 14:31 ` Michal Hocko
2016-11-29 7:57 ` Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 06/12] mm: thp: enable thp migration in generic path Naoya Horiguchi
2016-11-28 14:33 ` Michal Hocko
2016-11-29 8:16 ` Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 07/12] mm: thp: check pmd migration entry in common path Naoya Horiguchi
2016-11-08 0:23 ` kbuild test robot
2016-11-08 1:22 ` Naoya Horiguchi
2016-11-10 8:36 ` Anshuman Khandual
2016-11-10 9:12 ` Naoya Horiguchi
2016-11-10 9:08 ` Hillf Danton
2016-11-10 9:21 ` Naoya Horiguchi
2016-11-10 9:28 ` Hillf Danton
2016-11-10 9:34 ` Naoya Horiguchi
2016-11-17 23:56 ` Kirill A. Shutemov
2016-11-29 6:46 ` Naoya Horiguchi
2016-11-28 14:35 ` Michal Hocko
2016-11-07 23:31 ` [PATCH v2 08/12] mm: soft-dirty: keep soft-dirty bits over thp migration Naoya Horiguchi
2016-11-10 8:38 ` Anshuman Khandual
2016-11-10 9:13 ` Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 09/12] mm: hwpoison: soft offline supports " Naoya Horiguchi
2016-11-10 10:31 ` Balbir Singh
2016-11-10 23:58 ` Naoya Horiguchi
2016-11-14 23:22 ` Balbir Singh
2016-11-07 23:31 ` [PATCH v2 10/12] mm: mempolicy: mbind and migrate_pages support " Naoya Horiguchi
2016-11-25 12:27 ` Anshuman Khandual
2016-11-29 7:07 ` Naoya Horiguchi
2016-11-07 23:31 ` [PATCH v2 11/12] mm: migrate: move_pages() supports " Naoya Horiguchi
2016-11-18 0:01 ` Kirill A. Shutemov
2016-11-07 23:31 ` [PATCH v2 12/12] mm: memory_hotplug: memory hotremove " Naoya Horiguchi
2016-11-08 0:29 ` kbuild test robot
2016-11-08 0:30 ` kbuild test robot
2016-11-08 1:36 ` Naoya Horiguchi
2016-11-08 1:41 ` [PATCH] mm: fix unused variable warning Naoya Horiguchi
2016-11-09 2:32 ` [PATCH v2 00/12] mm: page migration enhancement for thp Balbir Singh
2016-11-09 4:59 ` Naoya Horiguchi
2016-11-09 21:28 ` Balbir Singh
2016-11-09 10:33 ` Anshuman Khandual
2016-11-09 23:52 ` Naoya Horiguchi
2016-11-10 14:01 ` Zi Yan
2016-11-11 3:48 ` Anshuman Khandual
2017-01-30 10:47 ` Anshuman Khandual
2017-01-31 19:54 ` Zi Yan
2017-02-03 3:12 ` Hillf Danton
2017-02-03 3:24 ` Zi Yan
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=20161111010834.GA28679@hori1.linux.bs1.fc.nec.co.jp \
--to=n-horiguchi@ah.jp.nec.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=bsingharora@gmail.com \
--cc=dave.hansen@intel.com \
--cc=hughd@google.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=nao.horiguchi@gmail.com \
--cc=vbabka@suse.cz \
--cc=xemul@parallels.com \
--cc=zi.yan@cs.rutgers.edu \
/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).