From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <koct9i@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v1 1/3] /proc/kpageflags: return KPF_BUDDY for "tail" buddy pages
Date: Thu, 4 Feb 2016 19:42:26 +0300 [thread overview]
Message-ID: <20160204164226.GA16895@esperanza> (raw)
In-Reply-To: <1454569683-17918-1-git-send-email-n-horiguchi@ah.jp.nec.com>
On Thu, Feb 04, 2016 at 04:08:01PM +0900, Naoya Horiguchi wrote:
> Currently /proc/kpageflags returns nothing for "tail" buddy pages, which
> is inconvenient when grasping how free pages are distributed. This patch
> sets KPF_BUDDY for such pages.
Looks reasonable to me,
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
>
> With this patch:
>
> $ grep MemFree /proc/meminfo ; tools/vm/page-types -b buddy
> MemFree: 3134992 kB
> flags page-count MB symbolic-flags long-symbolic-flags
> 0x0000000000000400 779272 3044 __________B_______________________________ buddy
> 0x0000000000000c00 4385 17 __________BM______________________________ buddy,mmap
> total 783657 3061
Why are buddy pages reported as mmapped? That looks weird. Shouldn't we
fix it? Something like this, may be?
--
From: Vladimir Davydov <vdavydov@virtuozzo.com>
Subject: [PATCH] proc: kpageflags: do not report buddy and balloon pages as
mapped
PageBuddy and PageBalloon are not usual page flags - they are identified
by a special negative (so as not to confuse with mapped pages) value of
page->_mapcount. Since /proc/kpageflags uses page_mapcount helper to
check if a page is mapped, it reports pages of these kinds as being
mapped, which is confusing. Fix that by replacing page_mapcount with
page_mapped.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
diff --git a/fs/proc/page.c b/fs/proc/page.c
index b2855eea5405..332450d87ea4 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -105,7 +105,7 @@ u64 stable_page_flags(struct page *page)
* Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
* simple test in page_mapcount() is not enough.
*/
- if (!PageSlab(page) && page_mapcount(page))
+ if (!PageSlab(page) && page_mapped(page))
u |= 1 << KPF_MMAP;
if (PageAnon(page))
u |= 1 << KPF_ANON;
--
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next prev parent reply other threads:[~2016-02-04 16:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-04 7:08 [PATCH v1 1/3] /proc/kpageflags: return KPF_BUDDY for "tail" buddy pages Naoya Horiguchi
2016-02-04 7:08 ` [PATCH v1 2/3] /proc/kpageflags: return KPF_SLAB for slab tail pages Naoya Horiguchi
2016-02-04 16:43 ` Vladimir Davydov
2016-02-04 7:08 ` [PATCH v1 3/3] tools/vm/page-types.c: support swap entry Naoya Horiguchi
2016-02-04 16:42 ` Vladimir Davydov [this message]
2016-02-04 23:29 ` [PATCH v1 1/3] /proc/kpageflags: return KPF_BUDDY for "tail" buddy pages Naoya Horiguchi
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