linux-kernel - Re: [PATCH RFC 3/4] mm/page_alloc: always move pages to the tail of the freelist in unset_migratetype

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Date:   Fri, 25 Sep 2020 15:57:44 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-acpi@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Michal Hocko <mhocko@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Mike Rapoport <rppt@...nel.org>,
        Scott Cheloha <cheloha@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH RFC 3/4] mm/page_alloc: always move pages to the tail of
 the freelist in unset_migratetype_isolate()

On Wed, Sep 16, 2020 at 08:34:10PM +0200, David Hildenbrand wrote:
> Page isolation doesn't actually touch the pages, it simply isolates
> pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist.
> 
> We already place pages to the tail of the freelists when undoing
> isolation via __putback_isolated_page(), let's do it in any case
> (e.g., if order == pageblock_order) and document the behavior.
> 
> This change results in all pages getting onlined via online_pages() to
> be placed to the tail of the freelist.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
> Cc: Mel Gorman <mgorman@...hsingularity.net>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Dave Hansen <dave.hansen@...el.com>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: Mike Rapoport <rppt@...nel.org>
> Cc: Scott Cheloha <cheloha@...ux.ibm.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Signed-off-by: David Hildenbrand <david@...hat.com>

LGTM.
Feel the same way about move_freepages_block_tail/move_freepages_block_tail
wrappers, I think we are better off without them.

Reviewed-by: Oscar Salvador <osalvador@...e.de>

Thanks

-- 
Oscar Salvador
SUSE L3