linux-kernel - Re: [PATCH v2 7/7] mm, page_alloc: disable pcplists during memory offline

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Date:   Thu, 8 Oct 2020 19:46:18 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Michal Hocko <mhocko@...e.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 7/7] mm, page_alloc: disable pcplists during memory
 offline

On 10/8/20 2:45 PM, Michal Hocko wrote:
> On Thu 08-10-20 13:42:01, Vlastimil Babka wrote:
>> Memory offline relies on page isolation can race with process freeing pages to
>> pcplists in a way that a page from isolated pageblock can end up on pcplist.
> 
> "Memory offlining relies on page isolation to guarantee a forward
> progress because pages cannot be reused while they are isolated. But the
> page isolation itself doesn't prevent from races while freed pages are
> stored on pcp lists and thus can be reused.
> "

Much better, thanks.