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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mel@csn.ul.ie>, Hugh Dickins <hughd@google.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Andi Kleen <andi@firstfloor.org>, Hillf Danton <dhillf@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/10] memory-hotplug: enable memory hotplug to handle hugepage
Date: Wed, 27 Mar 2013 17:58:28 -0400	[thread overview]
Message-ID: <1364421508-fjm1vfw0-mutt-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <1364419759-a5hijyn0-mutt-n-horiguchi@ah.jp.nec.com>

On Wed, Mar 27, 2013 at 05:29:19PM -0400, Naoya Horiguchi wrote:
...
> > If we made sure that all page on the hugepage_freelists have reference
> > 0 (which is now not the case and it is yet another source of confusion)
> > then the whole loop could be replaced by page_count check.
> 
> I think that free hugepages have refcount 0, but hwpoisoned hugepages
> have also refcount 0. But hwpoison can happen only on limited hardware
> and we consider them as exceptional, so replacing page_count check and
> checking PG_hwpoisoned flag looks more reasonable to me.

Sorry, my mistake. Hwpoisoned hugepages have refcount 1, so there's
no problem on using page_count check.

Naoya

WARNING: multiple messages have this Message-ID (diff)
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mel@csn.ul.ie>, Hugh Dickins <hughd@google.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Andi Kleen <andi@firstfloor.org>, Hillf Danton <dhillf@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/10] memory-hotplug: enable memory hotplug to handle hugepage
Date: Wed, 27 Mar 2013 17:58:28 -0400	[thread overview]
Message-ID: <1364421508-fjm1vfw0-mutt-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <1364419759-a5hijyn0-mutt-n-horiguchi@ah.jp.nec.com>

On Wed, Mar 27, 2013 at 05:29:19PM -0400, Naoya Horiguchi wrote:
...
> > If we made sure that all page on the hugepage_freelists have reference
> > 0 (which is now not the case and it is yet another source of confusion)
> > then the whole loop could be replaced by page_count check.
> 
> I think that free hugepages have refcount 0, but hwpoisoned hugepages
> have also refcount 0. But hwpoison can happen only on limited hardware
> and we consider them as exceptional, so replacing page_count check and
> checking PG_hwpoisoned flag looks more reasonable to me.

Sorry, my mistake. Hwpoisoned hugepages have refcount 1, so there's
no problem on using page_count check.

Naoya

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  reply	other threads:[~2013-03-27 21:59 UTC|newest]

Thread overview: 132+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-22 20:23 [PATCH v2 0/10] extend hugepage migration Naoya Horiguchi
2013-03-22 20:23 ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 01/10] migrate: add migrate_entry_wait_huge() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-23 15:55   ` Rik van Riel
2013-03-23 15:55     ` Rik van Riel
2013-03-25 10:13   ` Michal Hocko
2013-03-25 10:13     ` Michal Hocko
2013-03-26  4:25     ` Naoya Horiguchi
2013-03-26  4:25       ` Naoya Horiguchi
2013-04-05 20:33   ` KOSAKI Motohiro
2013-04-05 20:33     ` KOSAKI Motohiro
2013-04-08 20:00     ` Naoya Horiguchi
2013-04-08 20:00       ` Naoya Horiguchi
2013-04-05 20:33   ` KOSAKI Motohiro
2013-04-05 20:33     ` KOSAKI Motohiro
2013-03-22 20:23 ` [PATCH 02/10] migrate: make core migration code aware of hugepage Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 10:57   ` Michal Hocko
2013-03-25 10:57     ` Michal Hocko
2013-03-26  4:33     ` Naoya Horiguchi
2013-03-26  4:33       ` Naoya Horiguchi
2013-03-26  8:49       ` Michal Hocko
2013-03-26  8:49         ` Michal Hocko
2013-04-05 20:41         ` KOSAKI Motohiro
2013-04-05 20:41           ` KOSAKI Motohiro
2013-03-22 20:23 ` [PATCH 03/10] soft-offline: use migrate_pages() instead of migrate_huge_page() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 12:31   ` Michal Hocko
2013-03-25 12:31     ` Michal Hocko
2013-03-26  4:34     ` Naoya Horiguchi
2013-03-26  4:34       ` Naoya Horiguchi
2013-03-26  9:49       ` Michal Hocko
2013-03-26  9:49         ` Michal Hocko
2013-03-26 20:35         ` Naoya Horiguchi
2013-03-26 20:35           ` Naoya Horiguchi
2013-03-27 13:00           ` Michal Hocko
2013-03-27 13:00             ` Michal Hocko
2013-04-05 21:11             ` KOSAKI Motohiro
2013-04-05 21:11               ` KOSAKI Motohiro
2013-03-26 11:29   ` Aneesh Kumar K.V
2013-03-26 11:29     ` Aneesh Kumar K.V
2013-03-27 13:52     ` Michal Hocko
2013-03-27 13:52       ` Michal Hocko
2013-03-27 19:19       ` Naoya Horiguchi
2013-03-27 19:19         ` Naoya Horiguchi
2013-03-28  8:53         ` Michal Hocko
2013-03-28  8:53           ` Michal Hocko
2013-03-29  5:26       ` Aneesh Kumar K.V
2013-03-29  5:26         ` Aneesh Kumar K.V
2013-03-29  9:36         ` Michal Hocko
2013-03-29  9:36           ` Michal Hocko
2013-04-01  5:13       ` Aneesh Kumar K.V
2013-04-01  5:13         ` Aneesh Kumar K.V
2013-04-02  9:45         ` Michal Hocko
2013-04-02  9:45           ` Michal Hocko
2013-03-22 20:23 ` [PATCH 04/10] migrate: clean up migrate_huge_page() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-04-05 21:13   ` KOSAKI Motohiro
2013-04-05 21:13     ` KOSAKI Motohiro
2013-03-22 20:23 ` [PATCH 05/10] migrate: add hugepage migration code to migrate_pages() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 13:04   ` Michal Hocko
2013-03-25 13:04     ` Michal Hocko
2013-03-26  5:13     ` Naoya Horiguchi
2013-03-26  5:13       ` Naoya Horiguchi
2013-03-26  8:55       ` Michal Hocko
2013-03-26  8:55         ` Michal Hocko
2013-04-05 21:17   ` KOSAKI Motohiro
2013-04-05 21:17     ` KOSAKI Motohiro
2013-04-08 20:21     ` Naoya Horiguchi
2013-04-08 20:21       ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 06/10] migrate: add hugepage migration code to move_pages() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 13:36   ` Michal Hocko
2013-03-25 13:36     ` Michal Hocko
2013-03-26  7:06     ` Naoya Horiguchi
2013-03-26  7:06       ` Naoya Horiguchi
2013-03-26 10:02       ` Michal Hocko
2013-03-26 10:02         ` Michal Hocko
2013-03-26 20:37         ` Naoya Horiguchi
2013-03-26 20:37           ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 07/10] mbind: add hugepage migration code to mbind() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 13:49   ` Michal Hocko
2013-03-25 13:49     ` Michal Hocko
2013-04-05 22:23     ` KOSAKI Motohiro
2013-04-05 22:23       ` KOSAKI Motohiro
2013-04-06  7:04       ` Michal Hocko
2013-04-06  7:04         ` Michal Hocko
2013-04-05 22:18   ` KOSAKI Motohiro
2013-04-05 22:18     ` KOSAKI Motohiro
2013-04-08 20:25     ` Naoya Horiguchi
2013-04-08 20:25       ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 08/10] migrate: remove VM_HUGETLB from vma flag check in vma_migratable() Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 09/10] memory-hotplug: enable memory hotplug to handle hugepage Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 15:09   ` Michal Hocko
2013-03-25 15:09     ` Michal Hocko
2013-03-26 18:23     ` Naoya Horiguchi
2013-03-26 18:23       ` Naoya Horiguchi
2013-03-27 14:19       ` Michal Hocko
2013-03-27 14:19         ` Michal Hocko
2013-03-27 21:29         ` Naoya Horiguchi
2013-03-27 21:29           ` Naoya Horiguchi
2013-03-27 21:58           ` Naoya Horiguchi [this message]
2013-03-27 21:58             ` Naoya Horiguchi
2013-03-27 22:55           ` Michal Hocko
2013-03-27 22:55             ` Michal Hocko
2013-03-26 12:01   ` Aneesh Kumar K.V
2013-03-26 12:01     ` Aneesh Kumar K.V
2013-03-27 19:28     ` Naoya Horiguchi
2013-03-27 19:28       ` Naoya Horiguchi
2013-04-06  0:13   ` KOSAKI Motohiro
2013-04-06  0:13     ` KOSAKI Motohiro
2013-04-09 20:07     ` Naoya Horiguchi
2013-04-09 20:07       ` Naoya Horiguchi
2013-04-09 21:27       ` KOSAKI Motohiro
2013-04-09 21:27         ` KOSAKI Motohiro
2013-04-09 22:43         ` Naoya Horiguchi
2013-04-09 22:43           ` Naoya Horiguchi
2013-04-10  1:56           ` KOSAKI Motohiro
2013-04-10  1:56             ` KOSAKI Motohiro
2013-04-10  2:24             ` Naoya Horiguchi
2013-04-10  2:24               ` Naoya Horiguchi
2013-03-22 20:23 ` [PATCH 10/10] prepare to remove /proc/sys/vm/hugepages_treat_as_movable Naoya Horiguchi
2013-03-22 20:23   ` Naoya Horiguchi
2013-03-25 15:12   ` Michal Hocko
2013-03-25 15:12     ` Michal Hocko
2013-04-06  0:15     ` KOSAKI Motohiro
2013-04-06  0:15       ` KOSAKI Motohiro

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