linux-kernel - Re: [PATCH 8/9] mm, page_alloc: drain all pcplists during memory offline

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Message-ID: <20201005140330.GD4555@dhcp22.suse.cz>
Date:   Mon, 5 Oct 2020 16:03:30 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Oscar Salvador <osalvador@...e.de>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 8/9] mm, page_alloc: drain all pcplists during memory
 offline

On Fri 25-09-20 12:46:27, David Hildenbrand wrote:
> On 22.09.20 16:37, Vlastimil Babka wrote:
[...]
> > +/*
> > + * Spill all the per-cpu pages from all CPUs back into the buddy allocator.
> > + *
> > + * When zone parameter is non-NULL, spill just the single zone's pages.
> > + *
> > + * Note that this can be extremely slow as the draining happens in a workqueue.
> > + */
> > +void drain_all_pages(struct zone *zone)
> > +{
> > +	__drain_all_pages(zone, false);
> > +}
> > +
> >  #ifdef CONFIG_HIBERNATION
> >  
> >  /*
> > 
> 
> Interesting race. Instead of this ugly __drain_all_pages() with a
> boolean parameter, can we have two properly named functions to be used
> in !page_alloc.c code without scratching your head what the difference is?

I tend to agree here. I would even fold this into the next patch because
disable/enable interface is much more manageable.

-- 
Michal Hocko
SUSE Labs