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From: Vlastimil Babka <vbabka@suse.cz>
To: Xishi Qiu <qiuxishi@huawei.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Linux MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target()
Date: Mon, 18 Jul 2016 10:05:44 +0200	[thread overview]
Message-ID: <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> (raw)
In-Reply-To: <578C8C8A.8000007@huawei.com>

On 07/18/2016 10:00 AM, Xishi Qiu wrote:
> On 2016/7/18 13:51, Joonsoo Kim wrote:
>
>> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote:
>>> alloc_migrate_target() is called from migrate_pages(), and the page
>>> is always from user space, so we can add __GFP_HIGHMEM directly.
>>
>> No, all migratable pages are not from user space. For example,
>> blockdev file cache has __GFP_MOVABLE and migratable but it has no
>> __GFP_HIGHMEM and __GFP_USER.
>>
>
> Hi Joonsoo,
>
> So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;"
> is not correct?

It's not incorrect. GFP_USER just specifies some reclaim flags, and may 
perhaps restrict allocation through __GFP_HARDWALL, where the original
page could have been allocated without the restriction. But it doesn't 
put the place in an unexpected address range, as placing a non-highmem 
page into highmem could. __GFP_MOVABLE then just controls a heuristic 
for placement within a zone.

>> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE.
>>
>
> Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing
> mem-hotplug?

I don't understand the question here, can you rephrase with more detail? 
Thanks.

> Thanks,
> Xishi Qiu
>
>> Thanks.
>>
>>
>> .
>>
>
>
>

WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz>
To: Xishi Qiu <qiuxishi@huawei.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Linux MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target()
Date: Mon, 18 Jul 2016 10:05:44 +0200	[thread overview]
Message-ID: <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> (raw)
In-Reply-To: <578C8C8A.8000007@huawei.com>

On 07/18/2016 10:00 AM, Xishi Qiu wrote:
> On 2016/7/18 13:51, Joonsoo Kim wrote:
>
>> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote:
>>> alloc_migrate_target() is called from migrate_pages(), and the page
>>> is always from user space, so we can add __GFP_HIGHMEM directly.
>>
>> No, all migratable pages are not from user space. For example,
>> blockdev file cache has __GFP_MOVABLE and migratable but it has no
>> __GFP_HIGHMEM and __GFP_USER.
>>
>
> Hi Joonsoo,
>
> So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;"
> is not correct?

It's not incorrect. GFP_USER just specifies some reclaim flags, and may 
perhaps restrict allocation through __GFP_HARDWALL, where the original
page could have been allocated without the restriction. But it doesn't 
put the place in an unexpected address range, as placing a non-highmem 
page into highmem could. __GFP_MOVABLE then just controls a heuristic 
for placement within a zone.

>> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE.
>>
>
> Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing
> mem-hotplug?

I don't understand the question here, can you rephrase with more detail? 
Thanks.

> Thanks,
> Xishi Qiu
>
>> Thanks.
>>
>>
>> .
>>
>
>
>

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  reply	other threads:[~2016-07-18  8:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-15  2:47 [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target() Xishi Qiu
2016-07-15  2:47 ` Xishi Qiu
2016-07-15  2:51 ` [PATCH 2/2] mem-hotplug: use different mempolicy in alloc_migrate_target() Xishi Qiu
2016-07-15  2:51   ` Xishi Qiu
2016-07-18  8:00   ` Vlastimil Babka
2016-07-18  8:00     ` Vlastimil Babka
2016-07-18  5:51 ` [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target() Joonsoo Kim
2016-07-18  5:51   ` Joonsoo Kim
2016-07-18  7:45   ` Vlastimil Babka
2016-07-18  7:45     ` Vlastimil Babka
2016-07-18  8:00   ` Xishi Qiu
2016-07-18  8:00     ` Xishi Qiu
2016-07-18  8:05     ` Vlastimil Babka [this message]
2016-07-18  8:05       ` Vlastimil Babka
2016-07-18  8:31       ` Xishi Qiu
2016-07-18  8:31         ` Xishi Qiu
2016-07-19  6:50         ` Joonsoo Kim
2016-07-19  6:50           ` Joonsoo Kim
2016-07-19  7:18           ` Xishi Qiu
2016-07-19  7:18             ` Xishi Qiu
2016-07-19 19:05             ` David Rientjes
2016-07-19 19:05               ` David Rientjes

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