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From: Andrea Arcangeli <aarcange@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Christoph Lameter <cl@gentwo.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH, RFC 00/10] THP refcounting redesign
Date: Wed, 11 Jun 2014 00:04:51 +0200	[thread overview]
Message-ID: <20140610220451.GG19660@redhat.com> (raw)
In-Reply-To: <20140610204640.GA9594@node.dhcp.inet.fi>

On Tue, Jun 10, 2014 at 11:46:40PM +0300, Kirill A. Shutemov wrote:
> Agreed. The patchset drops tail page refcounting.

Very possibly I misread something or a later patch fixes this up, I
just did a basic code review, but from the new code of split_huge_page
it looks like it returns -EBUSY after checking the individual tail
page refcounts, so it's not clear how that defines as "dropped".

+       for (i = 0; i < HPAGE_PMD_NR; i++)
+               tail_count += page_mapcount(page + i);
+       if (tail_count != page_count(page) - 1) {
+               BUG_ON(tail_count > page_count(page) - 1);
+               compound_unlock(page);
+               spin_unlock_irq(&zone->lru_lock);
+               return -EBUSY;

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  parent reply	other threads:[~2014-06-10 22:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-09 16:04 [PATCH, RFC 00/10] THP refcounting redesign Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 01/10] mm, thp: drop FOLL_SPLIT Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 02/10] mm: change PageAnon() to work on tail pages Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 03/10] thp: rename split_huge_page_pmd() to split_huge_pmd() Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 04/10] thp: PMD splitting without splitting compound page Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 05/10] mm, vmstats: new THP splitting event Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 06/10] thp: implement new split_huge_page() Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 07/10] mm, thp: remove infrastructure for handling splitting PMDs Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 08/10] x86, thp: remove " Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 09/10] futex, thp: remove special case for THP in get_futex_key Kirill A. Shutemov
2014-06-09 16:04 ` [PATCH, RFC 10/10] thp: update documentation Kirill A. Shutemov
2014-06-10  8:10 ` [PATCH, RFC 00/10] THP refcounting redesign Vlastimil Babka
2014-06-10 13:52   ` Kirill A. Shutemov
2014-06-10 14:29     ` Andrea Arcangeli
2014-06-10 15:24       ` Kirill A. Shutemov
2014-06-10 20:25 ` Christoph Lameter
2014-06-10 20:46   ` Kirill A. Shutemov
2014-06-10 21:21     ` Christoph Lameter
2014-06-10 22:04     ` Andrea Arcangeli [this message]
2014-06-10 22:14       ` Kirill A. Shutemov
2014-06-10 22:37         ` Andrea Arcangeli
2014-06-10 21:58   ` Andrea Arcangeli

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