From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: mm: fix BUG in __split_huge_page_pmd
Date: Tue, 15 Oct 2013 15:28:50 -0400 [thread overview]
Message-ID: <1381865330-8nb86ucy-mutt-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <20131015185510.GH3479@redhat.com>
On Tue, Oct 15, 2013 at 08:55:10PM +0200, Andrea Arcangeli wrote:
> On Tue, Oct 15, 2013 at 10:53:10AM -0700, Hugh Dickins wrote:
> > I'm afraid Andrea's mail about concurrent madvises gives me far more
> > to think about than I have time for: seems to get into problems he
> > knows a lot about but I'm unfamiliar with. If this patch looks good
> > for now on its own, let's put it in; but no problem if you guys prefer
> > to wait for a fuller solution of more problems, we can ride with this
> > one internally for the moment.
>
> I'm very happy with the patch and I think it's a correct fix for the
> COW scenario which is deterministic so the looping makes a meaningful
> difference for it. If we wouldn't loop, part of the copied page
> wouldn't be zapped after the COW.
I like this patch, too.
If we have the loop in __split_huge_page_pmd as suggested in this patch,
can we assume that the pmd is stable after __split_huge_page_pmd returns?
If it's true, we can remove pmd_none_or_trans_huge_or_clear_bad check
in the callers side (zap_pmd_range and some other page table walking code.)
Naoya Horiguchi
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next prev parent reply other threads:[~2013-10-15 19:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 11:08 Hugh Dickins
2013-10-15 11:32 ` Kirill A. Shutemov
2013-10-15 14:41 ` Andrea Arcangeli
2013-10-15 14:34 ` Andrea Arcangeli
2013-10-15 14:48 ` Kirill A. Shutemov
2013-10-15 15:58 ` Andrea Arcangeli
2013-10-15 17:53 ` Hugh Dickins
2013-10-15 18:55 ` Andrea Arcangeli
2013-10-15 19:28 ` Naoya Horiguchi [this message]
2013-10-15 19:44 ` Andrea Arcangeli
2013-10-15 20:16 ` Naoya Horiguchi
2013-10-15 20:30 ` Andrea Arcangeli
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