From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
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>,
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 6/6] mm/gup: migrate pinned pages out of movable zone
Date: Fri, 4 Dec 2020 11:24:56 -0500 [thread overview]
Message-ID: <CA+CK2bA18wXtETPpz4eeX02oagg1fyW=yNuN4UZVpBW0V4A1CQ@mail.gmail.com> (raw)
In-Reply-To: <20201203193607.GV5487@ziepe.ca>
On Thu, Dec 3, 2020 at 2:36 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Thu, Dec 03, 2020 at 02:15:36PM -0500, Pavel Tatashin wrote:
>
> > I studied some more, and I think this is not a race:
> > list_add_tail(&head->lru, &cma_page_list) is called only when
> > isolate_lru_page(head) succeeds.
> > isolate_lru_page(head) succeeds only when PageLRU(head) is true.
> > However, in this function we also clear LRU flag before returning
> > success.
> > This means, that if we race with another thread, the other thread
> > won't get to unprotected list_add_tail(&head->lru, &cma_page_list)
> > until head is is back on LRU list.
>
> Oh interesting, I totally didn't see how that LRU stuff is
> working. So.. this creates a ridiculously expensive spin lock? Not
> broken, but yikes :|
Not really a spin lock, the second thread won't be able to isolate
this page, and will skip migration of this page.
>
> Jason
next prev parent reply other threads:[~2020-12-04 16:25 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
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 [this message]
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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