From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Michal Hocko <mhocko@suse.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
David Hildenbrand <david@redhat.com>,
Oscar Salvador <osalvador@suse.de>,
Dan Williams <dan.j.williams@intel.com>,
Sasha Levin <sashal@kernel.org>,
Tyler Hicks <tyhicks@linux.microsoft.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
mike.kravetz@oracle.com, Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Jason Gunthorpe <jgg@ziepe.ca>,
Peter Zijlstra <peterz@infradead.org>,
Mel Gorman <mgorman@suse.de>,
Matthew Wilcox <willy@infradead.org>,
David Rientjes <rientjes@google.com>,
John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH 4/6] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_NOMOVABLE
Date: Thu, 3 Dec 2020 10:02:01 -0500 [thread overview]
Message-ID: <CA+CK2bAqXcMjxo9F5_0HP8kPbDjnewxcTpVNBbaVZZjhM4FMEg@mail.gmail.com> (raw)
In-Reply-To: <20201203085744.GZ17338@dhcp22.suse.cz>
On Thu, Dec 3, 2020 at 3:57 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Wed 02-12-20 00:23:28, Pavel Tatashin wrote:
> > PF_MEMALLOC_NOCMA is used for longterm pinning and has an effect of
> > clearing _GFP_MOVABLE or prohibiting allocations from ZONE_MOVABLE.
>
> This is not precise. You are mixing the implementation and the intention
> here. I would say "PF_MEMALLOC_NOCMA is used ot guarantee that the
> allocator will not return pages that might belong to CMA region. This is
> currently used for long term gup to make sure that such pins are not
> going to be done on any CMA pages."
>
> > We will prohibit allocating any pages that are getting
> > longterm pinned from ZONE_MOVABLE, and we would want to unify and re-use
> > this flag. So, rename it to generic PF_MEMALLOC_NOMOVABLE.
> > Also re-name:
> > memalloc_nocma_save()/memalloc_nocma_restore
> > to
> > memalloc_nomovable_save()/memalloc_nomovable_restore()
> > and make the new functions common.
>
> This is hard to parse for me. I would go with something like:
> "
> When PF_MEMALLOC_NOCMA has been introduced we haven't realized that it
> is focusing on CMA pages too much and that there is larger class of
> pages that need the same treatment. MOVABLE zone cannot contain
> any long term pins as well so it makes sense to reuse and redefine this
> flag for that usecase as well. Rename the flag to PF_MEMALLOC_NOMOVABLE
> which defines an allocation context which can only get pages suitable
> for long-term pins.
> "
I will address the above with your suggested wording.
>
> Btw. the naming is hard but PF_MEMALLOC_NOMOVABLE is a bit misnomer. CMA
> pages are not implicitly movable. So in fact we do care more about
> pinning than movability. PF_MEMALLOC_PIN or something similar would be
> better fit for the overal intention.
Sounds good, I will rename with PF_MEMALLOC_PIN
>
> Other than that looks good to me. Thanks!
Thank you,
Pasha
next prev parent reply other threads:[~2020-12-03 15:03 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 5:23 [PATCH 0/6] prohibit pinning pages in ZONE_MOVABLE Pavel Tatashin
2020-12-02 5:23 ` [PATCH 1/6] mm/gup: perform check_dax_vmas only when FS_DAX is enabled Pavel Tatashin
2020-12-02 16:22 ` Ira Weiny
2020-12-02 18:15 ` Pavel Tatashin
2020-12-02 16:29 ` Jason Gunthorpe
2020-12-02 18:16 ` Pavel Tatashin
2020-12-03 7:59 ` John Hubbard
2020-12-03 14:52 ` Pavel Tatashin
2020-12-02 5:23 ` [PATCH 2/6] mm/gup: don't pin migrated cma pages in movable zone Pavel Tatashin
2020-12-02 16:31 ` David Hildenbrand
2020-12-02 18:17 ` Pavel Tatashin
2020-12-03 8:01 ` John Hubbard
2020-12-03 8:46 ` Michal Hocko
2020-12-03 14:58 ` Pavel Tatashin
2020-12-02 5:23 ` [PATCH 3/6] mm/gup: make __gup_longterm_locked common Pavel Tatashin
2020-12-02 16:31 ` Ira Weiny
2020-12-02 16:33 ` Ira Weiny
2020-12-02 18:19 ` Pavel Tatashin
2020-12-03 0:03 ` Pavel Tatashin
2020-12-03 8:03 ` John Hubbard
2020-12-03 15:02 ` Pavel Tatashin
2020-12-02 5:23 ` [PATCH 4/6] mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_NOMOVABLE Pavel Tatashin
2020-12-03 8:04 ` John Hubbard
2020-12-03 15:02 ` Pavel Tatashin
2020-12-03 8:57 ` Michal Hocko
2020-12-03 15:02 ` Pavel Tatashin [this message]
2020-12-02 5:23 ` [PATCH 5/6] mm: honor PF_MEMALLOC_NOMOVABLE for all allocations Pavel Tatashin
2020-12-03 8:17 ` John Hubbard
2020-12-03 15:06 ` Pavel Tatashin
2020-12-03 16:51 ` John Hubbard
2020-12-03 9:17 ` Michal Hocko
2020-12-03 15:15 ` Pavel Tatashin
2020-12-04 8:43 ` Michal Hocko
2020-12-04 8:54 ` Michal Hocko
2020-12-04 16:07 ` Pavel Tatashin
2020-12-02 5:23 ` [PATCH 6/6] mm/gup: migrate pinned pages out of movable zone Pavel Tatashin
2020-12-02 16:35 ` Jason Gunthorpe
2020-12-03 0:19 ` Pavel Tatashin
2020-12-03 1:08 ` Jason Gunthorpe
2020-12-03 1:34 ` Pavel Tatashin
2020-12-03 14:17 ` Jason Gunthorpe
2020-12-03 16:40 ` Pavel Tatashin
2020-12-03 16:59 ` Jason Gunthorpe
2020-12-03 17:14 ` Pavel Tatashin
2020-12-03 19:15 ` Pavel Tatashin
2020-12-03 19:36 ` Jason Gunthorpe
2020-12-04 16:24 ` Pavel Tatashin
2020-12-04 17:06 ` Jason Gunthorpe
2020-12-04 20:05 ` Daniel Jordan
2020-12-04 20:16 ` Pavel Tatashin
2020-12-08 2:27 ` Daniel Jordan
2020-12-04 20:52 ` Jason Gunthorpe
2020-12-08 2:48 ` Daniel Jordan
2020-12-08 13:24 ` Jason Gunthorpe
2020-12-03 8:22 ` John Hubbard
2020-12-03 15:55 ` Pavel Tatashin
2020-12-04 4:13 ` Joonsoo Kim
2020-12-04 17:43 ` Pavel Tatashin
2020-12-07 7:13 ` Joonsoo Kim
2020-12-04 4:02 ` [PATCH 0/6] prohibit pinning pages in ZONE_MOVABLE Joonsoo Kim
2020-12-04 15:55 ` Pavel Tatashin
2020-12-04 16:10 ` Jason Gunthorpe
2020-12-04 17:50 ` Pavel Tatashin
2020-12-04 18:01 ` David Hildenbrand
2020-12-04 18:10 ` Pavel Tatashin
2020-12-07 7:12 ` Joonsoo Kim
2020-12-07 12:13 ` Michal Hocko
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