linux-kernel - Re: [PATCH] mm/memory_hotplug: Make unpopulated zones PCP structures unreachable during hot remove

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Message-ID: <YHFS5OXrbyN68KSO@dhcp22.suse.cz>
Date:   Sat, 10 Apr 2021 09:25:52 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Oscar Salvador <osalvador@...e.de>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH] mm/memory_hotplug: Make unpopulated zones PCP structures
 unreachable during hot remove

On Fri 09-04-21 16:12:59, Mel Gorman wrote:
[...]
> If anything, the minimal "fix" is to simply delete IRQ disable/enable on
> the grounds that IRQs protect nothing and assume the existing hotplug
> paths guarantees the PCP cannot be used after zone_pcp_enable(). That
> should be the case already because all the pages have been freed and
> there is nothing to even put into the PCPs but I worried that the PCP
> structure itself might still be reachable even if it's useless which is
> why I freed the structure once they could not be reached via zonelists.

OK. Let's do that for now and I will put a follow up on my todo list.

Thanks!
-- 
Michal Hocko
SUSE Labs