From: Andrea Arcangeli <aarcange@redhat.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Michael J Wolf <mjwolf@us.ibm.com>
Subject: Re: [RFC][PATCH 5/6] teach smaps_pte_range() about THP pmds
Date: Tue, 1 Feb 2011 17:09:32 +0100 [thread overview]
Message-ID: <20110201160932.GY16981@random.random> (raw)
In-Reply-To: <1296572550.27022.2862.camel@nimitz>
On Tue, Feb 01, 2011 at 07:02:30AM -0800, Dave Hansen wrote:
> On Tue, 2011-02-01 at 11:11 +0100, Johannes Weiner wrote:
> > On Mon, Jan 31, 2011 at 04:34:03PM -0800, Dave Hansen wrote:
> > > + if (pmd_trans_huge(*pmd)) {
> > > + if (pmd_trans_splitting(*pmd)) {
> > > + spin_unlock(&walk->mm->page_table_lock);
> > > + wait_split_huge_page(vma->anon_vma, pmd);
> > > + spin_lock(&walk->mm->page_table_lock);
> > > + goto normal_ptes;
> > > + }
> > > + smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_SIZE, walk);
> > > + return 0;
> > > + }
> > > +normal_ptes:
> > > split_huge_page_pmd(walk->mm, pmd);
> >
> > This line can go away now...?
>
> I did this because I was unsure what keeps khugepaged away from the
> newly-split ptes between the wait_split_huge_page() and the
> reacquisition of the mm->page_table_lock. mmap_sem, perhaps?
Any of mmap_sem read mode, PG_lock and anon_vma_lock keeps khugepaged
away.
> Looking at follow_page() and some of the other wait_split_huge_page(),
> it looks like this is unnecessary.
When wait_split_huge_page returns after the pmd was splitting, the pmd
can't return huge under you as long as you hold any of the above.
--
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/ .
Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-02-01 16:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-01 0:33 [RFC][PATCH 0/6] more detailed per-process transparent hugepage statistics Dave Hansen
2011-02-01 0:33 ` [RFC][PATCH 1/6] count transparent hugepage splits Dave Hansen
2011-02-01 9:58 ` Johannes Weiner
2011-02-03 21:22 ` David Rientjes
2011-02-04 21:18 ` Andrea Arcangeli
2011-02-04 21:28 ` Dave Hansen
2011-02-01 0:33 ` [RFC][PATCH 2/6] pagewalk: only split huge pages when necessary Dave Hansen
2011-02-01 10:04 ` Johannes Weiner
2011-02-01 15:03 ` Dave Hansen
2011-02-03 21:22 ` David Rientjes
2011-02-03 21:33 ` Dave Hansen
2011-02-03 21:46 ` David Rientjes
2011-02-04 17:19 ` Dave Hansen
2011-02-04 21:10 ` Andrea Arcangeli
2011-02-01 0:34 ` [RFC][PATCH 3/6] break out smaps_pte_entry() from smaps_pte_range() Dave Hansen
2011-02-01 10:08 ` Johannes Weiner
2011-02-03 21:22 ` David Rientjes
2011-02-03 21:40 ` Dave Hansen
2011-02-01 0:34 ` [RFC][PATCH 4/6] pass pte size argument in to smaps_pte_entry() Dave Hansen
2011-02-01 10:09 ` Johannes Weiner
2011-02-03 21:22 ` David Rientjes
2011-02-01 0:34 ` [RFC][PATCH 5/6] teach smaps_pte_range() about THP pmds Dave Hansen
2011-02-01 10:11 ` Johannes Weiner
2011-02-01 15:02 ` Dave Hansen
2011-02-01 16:09 ` Andrea Arcangeli [this message]
2011-02-03 21:22 ` David Rientjes
2011-02-03 21:34 ` Dave Hansen
2011-02-01 0:34 ` [RFC][PATCH 6/6] have smaps show transparent huge pages Dave Hansen
2011-02-01 10:12 ` Johannes Weiner
2011-02-03 21:22 ` David Rientjes
2011-02-01 15:38 ` [RFC][PATCH 0/6] more detailed per-process transparent hugepage statistics Andrea Arcangeli
2011-02-01 17:15 ` Dave Hansen
2011-02-01 20:39 ` Andrea Arcangeli
2011-02-01 20:56 ` Dave Hansen
2011-02-02 0:07 ` Andrea Arcangeli
2011-02-08 17:54 ` Dave Hansen
2011-02-08 18:17 ` Andrea Arcangeli
2011-02-03 21:54 ` David Rientjes
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=20110201160932.GY16981@random.random \
--to=aarcange@redhat.com \
--cc=dave@linux.vnet.ibm.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mjwolf@us.ibm.com \
/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).