From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
Hugh Dickins <hughd@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andi Kleen <andi@firstfloor.org>, Hillf Danton <dhillf@gmail.com>,
Michal Hocko <mhocko@suse.cz>, Rik van Riel <riel@redhat.com>,
Wanpeng Li <liwanp@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org,
Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH 8/8] prepare to remove /proc/sys/vm/hugepages_treat_as_movable
Date: Thu, 01 Aug 2013 11:29:39 +0530 [thread overview]
Message-ID: <87vc3qvtmc.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1375302249-scfvftrh-mutt-n-horiguchi@ah.jp.nec.com>
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:
> On Wed, Jul 31, 2013 at 12:02:30AM +0530, Aneesh Kumar K.V wrote:
>> Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:
>>
>> > Now hugepages are definitely movable. So allocating hugepages from
>> > ZONE_MOVABLE is natural and we have no reason to keep this parameter.
>> > In order to allow userspace to prepare for the removal, let's leave
>> > this sysctl handler as noop for a while.
>>
>> I guess you still need to handle architectures for which pmd_huge is
>>
>> int pmd_huge(pmd_t pmd)
>> {
>> return 0;
>> }
>>
>> embedded powerpc is one. They don't store pte information at the PMD
>> level. Instead pmd contains a pointer to hugepage directory which
>> contain huge pte.
>
> It seems that this comment is for the whole series, not just for this
> patch, right?
>
> Some users of hugepage migration (mbind, move_pages, migrate_pages)
> walk over page tables to collect hugepages to be migrated, where
> hugepages are just ignored in such architectures due to pmd_huge.
> So no problem for these users.
>
> But the other users (softoffline, memory hotremove) choose hugepages
> to be migrated based on pfn, where they don't check pmd_huge.
> As you wrote, this can be problematic for such architectures.
> So I think of adding pmd_huge() check somewhere (in unmap_and_move_huge_page
> for example) to make it fail for such architectures.
Considering that we have architectures that won't support migrating
explicit hugepages with this patch series, is it ok to use
GFP_HIGHUSER_MOVABLE for hugepage allocation ?
-aneesh
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next prev parent reply other threads:[~2013-08-01 6:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-25 4:54 [PATCH v4 0/8] extend hugepage migration Naoya Horiguchi
2013-07-25 4:54 ` [PATCH 1/8] migrate: make core migration code aware of hugepage Naoya Horiguchi
2013-07-25 6:06 ` Hillf Danton
2013-07-30 18:28 ` Aneesh Kumar K.V
2013-07-30 18:48 ` Naoya Horiguchi
2013-07-25 4:54 ` [PATCH 2/8] soft-offline: use migrate_pages() instead of migrate_huge_page() Naoya Horiguchi
2013-07-25 6:09 ` Hillf Danton
2013-07-25 4:54 ` [PATCH 3/8] migrate: add hugepage migration code to migrate_pages() Naoya Horiguchi
2013-07-25 6:17 ` Hillf Danton
2013-07-25 4:54 ` [PATCH 4/8] migrate: add hugepage migration code to move_pages() Naoya Horiguchi
2013-07-25 4:55 ` [PATCH 5/8] mbind: add hugepage migration code to mbind() Naoya Horiguchi
2013-07-25 6:33 ` Hillf Danton
2013-07-25 4:55 ` [PATCH 6/8] migrate: remove VM_HUGETLB from vma flag check in vma_migratable() Naoya Horiguchi
2013-07-25 4:55 ` [PATCH 7/8] memory-hotplug: enable memory hotplug to handle hugepage Naoya Horiguchi
2013-07-25 4:55 ` [PATCH 8/8] prepare to remove /proc/sys/vm/hugepages_treat_as_movable Naoya Horiguchi
2013-07-30 18:32 ` Aneesh Kumar K.V
2013-07-31 20:24 ` Naoya Horiguchi
2013-08-01 5:59 ` Aneesh Kumar K.V [this message]
2013-08-02 2:43 ` Naoya Horiguchi
2013-08-06 1:52 ` Aneesh Kumar K.V
2013-08-06 4:30 ` Naoya Horiguchi
2013-08-05 20:27 ` [PATCH 9/8] hugetlb: add pmd_huge_support() to migrate only pmd-based hugepage Naoya Horiguchi
2013-08-06 1:56 ` Aneesh Kumar K.V
2013-08-06 4:48 ` Naoya Horiguchi
-- strict thread matches above, loose matches on Subject: below --
2013-07-18 21:34 [PATCH v3 0/8] extend hugepage migration Naoya Horiguchi
2013-07-18 21:34 ` [PATCH 8/8] prepare to remove /proc/sys/vm/hugepages_treat_as_movable Naoya Horiguchi
2013-07-24 3:46 ` Wanpeng Li
2013-07-24 3:46 ` Wanpeng Li
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