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From: Vlastimil Babka <vbabka@suse.cz>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>, Mel Gorman <mgorman@suse.de>,
	Rik van Riel <riel@redhat.com>, Christoph Lameter <cl@gentwo.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Steve Capper <steve.capper@linaro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>,
	Jerome Marchand <jmarchan@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv5 20/28] mm: differentiate page_mapped() from page_mapcount() for compound pages
Date: Mon, 18 May 2015 17:35:16 +0200	[thread overview]
Message-ID: <555A06B4.2000706@suse.cz> (raw)
In-Reply-To: <1429823043-157133-21-git-send-email-kirill.shutemov@linux.intel.com>

On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote:
> Let's define page_mapped() to be true for compound pages if any
> sub-pages of the compound page is mapped (with PMD or PTE).
>
> On other hand page_mapcount() return mapcount for this particular small
> page.
>
> This will make cases like page_get_anon_vma() behave correctly once we
> allow huge pages to be mapped with PTE.
>
> Most users outside core-mm should use page_mapcount() instead of
> page_mapped().

Does "should" mean that they do that now, or just that you would like 
them to? Should there be a warning before the function then?

>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Tested-by: Sasha Levin <sasha.levin@oracle.com>

> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -909,7 +909,16 @@ static inline pgoff_t page_file_index(struct page *page)

(not shown in the diff)

  * Return true if this page is mapped into pagetables.
>    */

Expand the comment? Especially if you put compound_head() there.

>   static inline int page_mapped(struct page *page)

Convert to proper bool while at it?

>   {
> -	return atomic_read(&(page)->_mapcount) + compound_mapcount(page) >= 0;
> +	int i;
> +	if (likely(!PageCompound(page)))
> +		return atomic_read(&page->_mapcount) >= 0;
> +	if (compound_mapcount(page))
> +		return 1;
> +	for (i = 0; i < hpage_nr_pages(page); i++) {
> +		if (atomic_read(&page[i]._mapcount) >= 0)
> +			return 1;
> +	}
> +	return 0;
>   }
>
>   /*

--
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  parent reply	other threads:[~2015-05-18 15:35 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-23 21:03 [PATCHv5 00/28] THP refcounting redesign Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 01/28] mm, proc: adjust PSS calculation Kirill A. Shutemov
2015-04-29 15:49   ` Jerome Marchand
2015-05-14 14:12   ` Vlastimil Babka
2015-05-15 10:56     ` Kirill A. Shutemov
2015-05-15 11:33       ` Vlastimil Babka
2015-05-15 11:43         ` Kirill A. Shutemov
2015-05-15 12:37           ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 02/28] rmap: add argument to charge compound page Kirill A. Shutemov
2015-04-29 15:53   ` Jerome Marchand
2015-04-30 11:52     ` Kirill A. Shutemov
2015-05-14 16:07   ` Vlastimil Babka
2015-05-15 11:14     ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 03/28] memcg: adjust to support new THP refcounting Kirill A. Shutemov
2015-05-15  7:44   ` Vlastimil Babka
2015-05-15 11:18     ` Kirill A. Shutemov
2015-05-15 14:57       ` Dave Hansen
2015-05-16 23:17         ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 04/28] mm, thp: adjust conditions when we can reuse the page on WP fault Kirill A. Shutemov
2015-04-29 15:54   ` Jerome Marchand
2015-05-15  9:15   ` Vlastimil Babka
2015-05-15 11:21     ` Kirill A. Shutemov
2015-05-15 11:35       ` Vlastimil Babka
2015-05-15 13:29         ` Kirill A. Shutemov
2015-05-19 13:00           ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 05/28] mm: adjust FOLL_SPLIT for new refcounting Kirill A. Shutemov
2015-05-15 11:05   ` Vlastimil Babka
2015-05-15 11:36     ` Kirill A. Shutemov
2015-05-15 12:01       ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 06/28] mm: handle PTE-mapped tail pages in gerneric fast gup implementaiton Kirill A. Shutemov
2015-04-29 15:56   ` Jerome Marchand
2015-05-15 12:46   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 07/28] thp, mlock: do not allow huge pages in mlocked area Kirill A. Shutemov
2015-04-29 15:58   ` Jerome Marchand
2015-05-15 12:56   ` Vlastimil Babka
2015-05-15 13:41     ` Kirill A. Shutemov
2015-05-19 14:37       ` Vlastimil Babka
2015-05-20 12:10         ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 08/28] khugepaged: ignore pmd tables with THP mapped with ptes Kirill A. Shutemov
2015-04-29 15:59   ` Jerome Marchand
2015-05-15 12:59   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 09/28] thp: rename split_huge_page_pmd() to split_huge_pmd() Kirill A. Shutemov
2015-04-29 16:00   ` Jerome Marchand
2015-05-15 13:08   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 10/28] mm, vmstats: new THP splitting event Kirill A. Shutemov
2015-04-29 16:02   ` Jerome Marchand
2015-05-15 13:10   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 11/28] mm: temporally mark THP broken Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 12/28] thp: drop all split_huge_page()-related code Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 13/28] mm: drop tail page refcounting Kirill A. Shutemov
2015-05-18  9:48   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 14/28] futex, thp: remove special case for THP in get_futex_key Kirill A. Shutemov
2015-05-18 11:49   ` Vlastimil Babka
2015-05-18 12:13     ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 15/28] ksm: prepare to new THP semantics Kirill A. Shutemov
2015-05-18 12:41   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 16/28] mm, thp: remove compound_lock Kirill A. Shutemov
2015-04-29 16:11   ` Jerome Marchand
2015-04-30 11:58     ` Kirill A. Shutemov
2015-05-18 12:57   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 17/28] mm, thp: remove infrastructure for handling splitting PMDs Kirill A. Shutemov
2015-04-29 16:14   ` Jerome Marchand
2015-04-30 12:03     ` Kirill A. Shutemov
2015-05-18 13:40   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 18/28] x86, " Kirill A. Shutemov
2015-04-29  9:13   ` Aneesh Kumar K.V
2015-04-23 21:03 ` [PATCHv5 19/28] mm: store mapcount for compound page separately Kirill A. Shutemov
2015-05-18 14:32   ` Vlastimil Babka
2015-05-19  3:55     ` Kirill A. Shutemov
2015-05-19  9:01       ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 20/28] mm: differentiate page_mapped() from page_mapcount() for compound pages Kirill A. Shutemov
2015-04-29 16:20   ` Jerome Marchand
2015-04-30 12:06     ` Kirill A. Shutemov
2015-05-18 15:35   ` Vlastimil Babka [this message]
2015-05-19  4:00     ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 21/28] mm, numa: skip PTE-mapped THP on numa fault Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 22/28] thp: implement split_huge_pmd() Kirill A. Shutemov
2015-05-19  8:25   ` Vlastimil Babka
2015-05-20 14:38     ` Kirill A. Shutemov
2015-04-23 21:03 ` [PATCHv5 23/28] thp: add option to setup migration entiries during PMD split Kirill A. Shutemov
2015-05-19 13:55   ` Vlastimil Babka
2015-04-23 21:03 ` [PATCHv5 24/28] thp, mm: split_huge_page(): caller need to lock page Kirill A. Shutemov
2015-05-19 13:55   ` Vlastimil Babka
2015-04-23 21:04 ` [PATCHv5 25/28] thp: reintroduce split_huge_page() Kirill A. Shutemov
2015-05-19 12:43   ` Vlastimil Babka
2015-04-23 21:04 ` [PATCHv5 26/28] thp: introduce deferred_split_huge_page() Kirill A. Shutemov
2015-05-19 13:54   ` Vlastimil Babka
2015-04-23 21:04 ` [PATCHv5 27/28] mm: re-enable THP Kirill A. Shutemov
2015-04-23 21:04 ` [PATCHv5 28/28] thp: update documentation Kirill A. Shutemov
2015-04-27 23:03 ` [PATCHv5 00/28] THP refcounting redesign Andrew Morton
2015-04-27 23:33   ` Kirill A. Shutemov
2015-04-30  8:25 ` [RFC PATCH 0/3] Remove _PAGE_SPLITTING from ppc64 Aneesh Kumar K.V
2015-04-30  8:25   ` [RFC PATCH 1/3] mm/thp: Use pmdp_splitting_flush_notify to clear pmd on splitting Aneesh Kumar K.V
2015-04-30 13:30     ` Kirill A. Shutemov
2015-04-30 15:59       ` Aneesh Kumar K.V
2015-04-30 16:47         ` Aneesh Kumar K.V
2015-04-30  8:25   ` [RFC PATCH 2/3] powerpc/thp: Remove _PAGE_SPLITTING and related code Aneesh Kumar K.V
2015-04-30  8:25   ` [RFC PATCH 3/3] mm/thp: Add new function to clear pmd on collapse Aneesh Kumar K.V
2015-05-15  8:55 ` [PATCHv5 00/28] THP refcounting redesign Vlastimil Babka
2015-05-15 13:31   ` Kirill A. Shutemov

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