linux-kernel - Re: [RFC PATCH v3 5/8] mm: page_isolation: check specified range for unmovable pages during isolation.

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Message-ID: <ead90b32-da2b-4d66-f103-6fbec0937e93@redhat.com>
Date:   Fri, 14 Jan 2022 14:38:30 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Zi Yan <ziy@...dia.com>, linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org,
        iommu@...ts.linux-foundation.org, Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Eric Ren <renzhengeek@...il.com>
Subject: Re: [RFC PATCH v3 5/8] mm: page_isolation: check specified range for
 unmovable pages during isolation.

On 05.01.22 22:47, Zi Yan wrote:
> From: Zi Yan <ziy@...dia.com>
> 
> Enable set_migratetype_isolate() to check specified sub-range for
> unmovable pages during isolation. Page isolation is done
> at max(MAX_ORDER_NR_PAEGS, pageblock_nr_pages) granularity, but not all
> pages within that granularity are intended to be isolated. For example,
> alloc_contig_range(), which uses page isolation, allows ranges without
> alignment. This commit makes unmovable page check only look for
> interesting pages, so that page isolation can succeed for any
> non-overlapping ranges.

Are you handling if we start checking in the middle of a compound page
and actually have to lookup the head to figure out if movable or not?

> 
> has_unmovable_pages() is moved to mm/page_isolation.c since it is only
> used by page isolation.

Please move that into a separate patch upfront, makes this patch much
easier to review.

-- 
Thanks,

David / dhildenb