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[142.162.115.133]) by smtp.gmail.com with ESMTPSA id m64sm12086816qkb.90.2021.01.25.06.28.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 06:28:20 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l42qp-006Vxe-HI; Mon, 25 Jan 2021 10:28:19 -0400 Date: Mon, 25 Jan 2021 10:28:19 -0400 From: Jason Gunthorpe To: Pavel Tatashin Cc: LKML , linux-mm , Andrew Morton , Vlastimil Babka , Michal Hocko , David Hildenbrand , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List , Ira Weiny , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v6 08/14] mm/gup: do not migrate zero page Message-ID: <20210125142819.GU4605@ziepe.ca> References: <20210120014333.222547-1-pasha.tatashin@soleen.com> <20210120014333.222547-9-pasha.tatashin@soleen.com> <20210120131400.GF4605@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jan 20, 2021 at 09:26:41AM -0500, Pavel Tatashin wrote: > I thought about this, and it would code a little cleaner. But, the > reason I did not is because zero_page is perfectly pinnable, it is not > pinnable only when it is in a movable zone (and it should not be in a > movable zones for other reasons as well), but that is another bug that > needs to be resolved, and once that bug is resolved this condition can > be removed from gup migration. My point is you've defined the zero page to be pinnable no matter what zone it is in, so is_pinnable(zero_page) == true Jason