linux-kernel - Re: [PATCH v3 4/6] mm: honor PF_MEMALLOC

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Date:   Tue, 15 Dec 2020 09:27:48 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Pavel Tatashin <pasha.tatashin@...een.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Dan Williams <dan.j.williams@...el.com>,
        Sasha Levin <sashal@...nel.org>,
        Tyler Hicks <tyhicks@...ux.microsoft.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, mike.kravetz@...cle.com,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Peter Zijlstra <peterz@...radead.org>,
        Mel Gorman <mgorman@...e.de>,
        Matthew Wilcox <willy@...radead.org>,
        David Rientjes <rientjes@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v3 4/6] mm: honor PF_MEMALLOC_PIN for all movable pages

On Tue 15-12-20 00:24:30, Pavel Tatashin wrote:
> On Mon, Dec 14, 2020 at 9:17 AM Michal Hocko <mhocko@...e.com> wrote:
> >
> > On Fri 11-12-20 15:21:38, Pavel Tatashin wrote:
> > [...]
> > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > index c2dea9ad0e98..4d8e7f801c66 100644
> > > --- a/mm/page_alloc.c
> > > +++ b/mm/page_alloc.c
> > > @@ -3802,16 +3802,12 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
> > >       return alloc_flags;
> > >  }
> > >
> > > -static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
> > > -                                     unsigned int alloc_flags)
> > > +static inline unsigned int cma_alloc_flags(gfp_t gfp_mask,
> > > +                                        unsigned int alloc_flags)
> >
> > Do you have any strong reason to rename? Even though the current
> 
> Yes :)
> 
> > implementation only does something for cma I do not think this is all
> > that important. The naming nicely fits with current_gfp_context so I
> > would stick with it.
> 
> I am renaming because current->flags is removed from this function,
> therefore keeping the name
> becomes misleading. This function only addresses cma flag check
> without looking at the thread local state now.

Fair enough. I still dislike cma being called out explicitly because
that is slightly misleading as well. gpf_to_alloc_flags would be more
explicit I believe. But I do not want to bikeshed this to death.

-- 
Michal Hocko
SUSE Labs