From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <js1304@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Christoph Lameter <cl@linux.com>, Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH] mm: fix wrong argument of migrate_huge_pages() in soft_offline_huge_page()
Date: Wed, 18 Jul 2012 13:45:41 +0530 [thread overview]
Message-ID: <87ipdlcwnm.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1207171526440.23015@chino.kir.corp.google.com>
David Rientjes <rientjes@google.com> writes:
> On Tue, 17 Jul 2012, Andrew Morton wrote:
>
>> > > Commit a6bc32b899223a877f595ef9ddc1e89ead5072b8 ('mm: compaction: introduce
>> > > sync-light migration for use by compaction') change declaration of
>> > > migrate_pages() and migrate_huge_pages().
>> > > But, it miss changing argument of migrate_huge_pages()
>> > > in soft_offline_huge_page(). In this case, we should call with MIGRATE_SYNC.
>> > > So change it.
>> > >
>> > > Additionally, there is mismatch between type of argument and function
>> > > declaration for migrate_pages(). So fix this simple case, too.
>> > >
>> > > Signed-off-by: Joonsoo Kim <js1304@gmail.com>
>> >
>> > Acked-by: David Rientjes <rientjes@google.com>
>> >
>> > Should be cc'd to stable for 3.3+.
>>
>> Well, why? I'm suspecting a switch from MIGRATE_SYNC_LIGHT to
>> MIGRATE_SYNC will have no discernable effect. Unless it triggers hitherto
>> unknkown about deadlocks...
>>
>> For a -stable backport we should have a description of the end-user
>> visible effects of the bug. This changelog lacked such a description.
>>
>
> I would put this:
>
> MIGRATE_SYNC_LIGHT will not aggressively attempt to defragment memory when
> allocating hugepages for migration with MIGRATE_SYNC_LIGHT, such as not
> defragmenting dirty pages, so MADV_SOFT_OFFLINE and
> /sys/devices/system/memory/soft_offline_page would be significantly
> less successful without this patch.
Is that true with hugetlb pages ? hugetlbfs_migrate_page doesn't seem to
use the mode argument at all. We do look at MIGRATE_SYNC if we fail to
get page lock, but other than that do we look at mode argument for
hugetlb pages ?
-aneesh
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prev parent reply other threads:[~2012-07-18 8:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-17 17:01 Joonsoo Kim
2012-07-17 20:42 ` David Rientjes
2012-07-17 20:49 ` Andrew Morton
2012-07-17 22:29 ` David Rientjes
2012-07-18 8:15 ` Aneesh Kumar K.V [this message]
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