From: Yang Shi <yang.shi@linux.alibaba.com>
To: Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@kernel.org>
Cc: akpm@linux-foundation.org, mgorman@techsingularity.net,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Eric Dumazet <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH] mm: mempolicy: handle vma with unmovable pages mapped correctly in mbind
Date: Wed, 19 Jun 2019 09:21:01 -0700 [thread overview]
Message-ID: <687f4e57-5c50-7900-645e-6ef3a5c1c0c7@linux.alibaba.com> (raw)
In-Reply-To: <21a0b20c-5b62-490e-ad8e-26b4b78ac095@suse.cz>
On 6/19/19 1:22 AM, Vlastimil Babka wrote:
> On 6/19/19 7:21 AM, Michal Hocko wrote:
>> On Tue 18-06-19 14:13:16, Yang Shi wrote:
>> [...]
>>> I used to have !__PageMovable(page), but it was removed since the
>>> aforementioned reason. I could add it back.
>>>
>>> For the temporary off LRU page, I did a quick search, it looks the most
>>> paths have to acquire mmap_sem, so it can't race with us here. Page
>>> reclaim/compaction looks like the only race. But, since the mapping should
>>> be preserved even though the page is off LRU temporarily unless the page is
>>> reclaimed, so we should be able to exclude temporary off LRU pages by
>>> calling page_mapping() and page_anon_vma().
>>>
>>> So, the fix may look like:
>>>
>>> if (!PageLRU(head) && !__PageMovable(page)) {
>>> if (!(page_mapping(page) || page_anon_vma(page)))
>>> return -EIO;
>> This is getting even more muddy TBH. Is there any reason that we have to
>> handle this problem during the isolation phase rather the migration?
> I think it was already said that if pages can't be isolated, then
> migration phase won't process them, so they're just ignored.
Yes，exactly.
> However I think the patch is wrong to abort immediately when
> encountering such page that cannot be isolated (AFAICS). IMHO it should
> still try to migrate everything it can, and only then return -EIO.
It is fine too. I don't see mbind semantics define how to handle such
case other than returning -EIO.
next prev parent reply other threads:[~2019-06-19 16:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1560797290-42267-1-git-send-email-yang.shi@linux.alibaba.com>
2019-06-18 13:02 ` [PATCH] mm: mempolicy: handle vma with unmovable pages mapped correctly in mbind Michal Hocko
2019-06-18 17:06 ` Yang Shi
2019-06-18 18:28 ` Michal Hocko
2019-06-18 21:13 ` Yang Shi
2019-06-19 5:21 ` Michal Hocko
2019-06-19 8:22 ` Vlastimil Babka
2019-06-19 16:21 ` Yang Shi [this message]
2019-06-19 18:19 ` Yang Shi
2019-06-20 7:18 ` Vlastimil Babka
2019-06-20 16:08 ` Yang Shi
2019-06-21 11:33 ` Vlastimil Babka
2019-06-21 18:23 ` Yang Shi
2019-06-19 8:18 ` Vlastimil Babka
2019-06-19 16:39 ` Yang Shi
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