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From: Michal Hocko <mhocko@suse.com>
To: Li Xinhai <lixinhai.lxh@gmail.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	akpm <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH v4] mm/mempolicy,hugetlb: Checking hstate for hugetlbfs page in vma_migratable
Date: Thu, 16 Jan 2020 16:18:03 +0100	[thread overview]
Message-ID: <20200116151803.GV19428@dhcp22.suse.cz> (raw)
In-Reply-To: <20200116215032206994102@gmail.com>

On Thu 16-01-20 21:50:34, Li Xinhai wrote:
> On 2020-01-16 at 17:56 Michal Hocko wrote:
> >On Thu 16-01-20 04:11:25, Li Xinhai wrote:
> >> Checking hstate at early phase when isolating page, instead of during
> >> unmap and move phase, to avoid useless isolation.
> >
> >Could you be more specific what you mean by isolation and why does it
> >matter? The patch description should really explain _why_ the change is
> >needed or desirable. 
> 
> The changelog can be improved:
> 
> vma_migratable() is called to check if pages in vma can be migrated
> before go ahead to isolate, unmap and move pages. For hugetlb pages,
> hugepage_migration_supported(struct hstate *h) is one factor which
> decide if migration is supported. In current code, this function is called
> from unmap_and_move_huge_page(), after isolating page has
> completed.
> This patch checks hstate from vma_migratable() and avoids isolating pages
> which are not supported.

This still explains what but not why this is relevant. If by isolating
pages you mean isolate_lru_page then this really a noop for hugetlb
pages. Or do I still misread your changelog?
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-01-16 15:18 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16  4:11 [PATCH v4] mm/mempolicy,hugetlb: Checking hstate for hugetlbfs page in vma_migratable Li Xinhai
2020-01-16  9:56 ` Michal Hocko
2020-01-16 13:50   ` Li Xinhai
2020-01-16 15:18     ` Michal Hocko [this message]
2020-01-16 15:38       ` Li Xinhai
2020-01-17  3:16         ` Li Xinhai
2020-01-18  3:11           ` Li Xinhai
2020-01-18 15:27             ` Li Xinhai
2020-01-20 10:12             ` Michal Hocko
2020-01-20 15:37               ` Li Xinhai
2020-01-20 16:05                 ` Michal Hocko
2020-01-21  3:42                   ` Anshuman Khandual
2020-01-21 13:08                     ` Li Xinhai
2020-01-21 12:44                   ` Li Xinhai
2020-01-20  9:21       ` Anshuman Khandual
2020-01-20 11:32         ` Michal Hocko
2020-01-21  3:22           ` Anshuman Khandual
2020-01-20 14:19         ` Li Xinhai
2020-01-22  6:05 ` Anshuman Khandual
2020-01-22 13:21   ` Li Xinhai
2020-01-23  7:48     ` Anshuman Khandual

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