From: Simon Jeons <simon.jeons@gmail.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Lin Feng <linfeng@cn.fujitsu.com>,
bcrl@kvack.org, viro@zeniv.linux.org.uk, khlebnikov@openvz.org,
walken@google.com, kamezawa.hiroyu@jp.fujitsu.com,
minchan@kernel.org, riel@redhat.com, rientjes@google.com,
isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com,
laijs@cn.fujitsu.com, jiang.liu@huawei.com, mhocko@suse.cz,
linux-mm@kvack.org, linux-aio@kvack.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: hotplug: implement non-movable version of get_user_pages() called get_user_pages_non_movable()
Date: Wed, 20 Feb 2013 17:58:22 +0800 [thread overview]
Message-ID: <51249E3E.9070909@gmail.com> (raw)
In-Reply-To: <20130205133244.GH21389@suse.de>
On 02/05/2013 09:32 PM, Mel Gorman wrote:
> On Tue, Feb 05, 2013 at 11:57:22AM +0000, Mel Gorman wrote:
>>>> + migrate_pre_flag = 1;
>>>> + }
>>>> +
>>>> + if (!isolate_lru_page(pages[i])) {
>>>> + inc_zone_page_state(pages[i], NR_ISOLATED_ANON +
>>>> + page_is_file_cache(pages[i]));
>>>> + list_add_tail(&pages[i]->lru, &pagelist);
>>>> + } else {
>>>> + isolate_err = 1;
>>>> + goto put_page;
>>>> + }
>> isolate_lru_page() takes the LRU lock every time.
> Credit to Michal Hocko for bringing this up but with the number of
> other issues I missed that this is also broken with respect to huge page
> handling. hugetlbfs pages will not be on the LRU so the isolation will mess
> up and the migration has to be handled differently. Ordinarily hugetlbfs
> pages cannot be allocated from ZONE_MOVABLE but it is possible to configure
> it to be allowed via /proc/sys/vm/hugepages_treat_as_movable. If this
> encounters a hugetlbfs page, it'll just blow up.
As you said, hugetlbfs pages are not in LRU list, then how can encounter
a hugetlbfs page and blow up?
>
> The other is that this almost certainly broken for transhuge page
> handling. gup returns the head and tail pages and ordinarily this is ok
When need gup thp? in kvm case?
> because the caller only cares about the physical address. Migration will
> also split a hugepage if it receives it but you are potentially adding
> tail pages to a list here and then migrating them. The split of the first
> page will get very confused. I'm not exactly sure what the result will be
> but it won't be pretty.
>
> Was THP enabled when this was tested? Was CONFIG_DEBUG_LIST enabled
> during testing?
>
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next prev parent reply other threads:[~2013-02-20 9:58 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-04 10:04 [PATCH 0/2] mm: hotplug: implement non-movable version of get_user_pages() to kill long-time pin pages Lin Feng
2013-02-04 10:04 ` [PATCH 1/2] mm: hotplug: implement non-movable version of get_user_pages() called get_user_pages_non_movable() Lin Feng
2013-02-05 0:06 ` Andrew Morton
2013-02-05 0:18 ` Andrew Morton
2013-02-05 3:09 ` Lin Feng
2013-02-05 21:13 ` Andrew Morton
2013-02-05 11:57 ` Mel Gorman
2013-02-05 13:32 ` Mel Gorman
2013-02-19 13:37 ` Lin Feng
2013-02-20 2:34 ` Lin Feng
2013-02-20 2:44 ` Wanpeng Li
2013-02-20 2:44 ` Wanpeng Li
[not found] ` <20130220024435.GA30208@hacker.(null)>
2013-02-20 2:59 ` Lin Feng
2013-02-20 9:58 ` Simon Jeons [this message]
2013-02-20 10:23 ` Lin Feng
2013-02-20 11:31 ` Simon Jeons
2013-02-20 11:54 ` Lin Feng
2013-02-06 2:26 ` Michel Lespinasse
2013-02-06 10:41 ` Mel Gorman
2013-02-18 10:34 ` Lin Feng
2013-02-18 15:17 ` Mel Gorman
2013-02-19 9:55 ` Lin Feng
2013-02-19 10:34 ` Mel Gorman
2013-02-04 10:04 ` [PATCH 2/2] fs/aio.c: use get_user_pages_non_movable() to pin ring pages when support memory hotremove Lin Feng
2013-02-04 15:18 ` Jeff Moyer
2013-02-04 23:02 ` Zach Brown
2013-02-05 5:35 ` Lin Feng
2013-02-05 5:06 ` Lin Feng
2013-02-05 0:58 ` [PATCH 0/2] mm: hotplug: implement non-movable version of get_user_pages() to kill long-time pin pages Minchan Kim
2013-02-05 4:42 ` Lin Feng
2013-02-05 5:25 ` Minchan Kim
2013-02-05 6:18 ` Lin Feng
2013-02-05 7:45 ` Minchan Kim
2013-02-05 8:27 ` Lin Feng
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