linux-kernel - Re: [PATCH 6/7] mm,hwpoison: Disable pcplists before grabbing a refcount

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Date:   Fri, 20 Nov 2020 01:33:33 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Oscar Salvador <osalvador@...e.de>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "n-horiguchi@...jp.nec.com" <n-horiguchi@...jp.nec.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/7] mm,hwpoison: Disable pcplists before grabbing a
 refcount

On Thu, Nov 19, 2020 at 11:57:15AM +0100, Oscar Salvador wrote:
> Currently, we have a sort of retry mechanism to make sure pages in
> pcp-lists are spilled to the buddy system, so we can handle those.
> 
> We can save us this extra checks with the new disable-pcplist mechanism
> that is available with [1].
> 
> zone_pcplist_disable makes sure to 1) disable pcplists, so any page
> that is freed up from that point onwards will end up in the buddy
> system and 2) drain pcplists, so those pages that already in pcplists
> are spilled to buddy.
> 
> With that, we can make a common entry point for grabbing a refcount
> from both soft_offline and memory_failure paths that is guarded by
> zone_pcplist_disable/zone_pcplist_enable.

This new mechanism provides a better solution to us.

> 
> [1] https://patchwork.kernel.org/project/linux-mm/cover/20201111092812.11329-1-vbabka@suse.cz/
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>

Thank you very much.

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>