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[209.85.220.65]) by mx.google.com with SMTPS id n17sor13634539qta.70.2019.03.25.09.45.23 for (Google Transport Security); Mon, 25 Mar 2019 09:45:23 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=ZDbQf6wF; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=azszLIWADnCz8AeAgm8+58HpL8DqZnCAWctdIVFE5Zo=; b=ZDbQf6wFJU+EYUfgK208d7q5xgEAsedfDWsH7HcS+TgxZe1Tssa2BPdsAG2/hwMAys rsvWpbV2F4p94YwmKTFIuX4ZYCNds18YVeb5XKR3N/q/IwU3EkNwJcTVzYn6EDh7fZln 2OZxPHIHWfFGj7YZXdyCqHS05W2dh7149lXSg4/ukEQUMHL7D7Y6NtaabG2aYj9KasxM PHuOzwzg4iM4288xlpCX0Y7+myHdwiQDA5aQ9iytY8LSSCnI+uBbm/mNp75vQ71uvTOh 1u0QcVedoEpv2k/lmslIikFO/JBL2Dw9XFQLEa1MLkr1UZsADEa008jT8NGlhOraW5UW A0zQ== X-Google-Smtp-Source: APXvYqwyqN1SmdoxO8BNg708b3bvqvBy5e7BsLNFvrI9L6R6ElZeTlrOFSa7GssTU28fSAH0U/YXsNRayrnRchybewU= X-Received: by 2002:ac8:2396:: with SMTP id q22mr22096706qtq.382.1553532323693; Mon, 25 Mar 2019 09:45:23 -0700 (PDT) MIME-Version: 1.0 References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-2-ira.weiny@intel.com> <20190325061941.GA16366@iweiny-DESK2.sc.intel.com> In-Reply-To: <20190325061941.GA16366@iweiny-DESK2.sc.intel.com> From: Dan Williams Date: Mon, 25 Mar 2019 09:45:12 -0700 Message-ID: Subject: Re: [RESEND 1/7] mm/gup: Replace get_user_pages_longterm() with FOLL_LONGTERM To: Ira Weiny Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , "Aneesh Kumar K . V" , Michal Hocko , linux-mm , Linux Kernel Mailing List , linux-mips@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , sparclinux@vger.kernel.org, linux-rdma , "netdev@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" 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 Mon, Mar 25, 2019 at 7:21 AM Ira Weiny wrote: [..] > > > @@ -1268,10 +1246,14 @@ static long check_and_migrate_cma_pages(unsigned long start, long nr_pages, > > > putback_movable_pages(&cma_page_list); > > > } > > > /* > > > - * We did migrate all the pages, Try to get the page references again > > > - * migrating any new CMA pages which we failed to isolate earlier. > > > + * We did migrate all the pages, Try to get the page references > > > + * again migrating any new CMA pages which we failed to isolate > > > + * earlier. > > > */ > > > - nr_pages = get_user_pages(start, nr_pages, gup_flags, pages, vmas); > > > + nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages, > > > + pages, vmas, NULL, > > > + gup_flags); > > > + > > > > Why did this need to change to __get_user_pages_locked? > > __get_uer_pages_locked() is now the "internal call" for get_user_pages. > > Technically it did not _have_ to change but there is no need to call > get_user_pages() again because the FOLL_TOUCH flags is already set. Also this > call then matches the __get_user_pages_locked() which was called on the pages > we migrated from. Mostly this keeps the code "symmetrical" in that we called > __get_user_pages_locked() on the pages we are migrating from and the same call > on the pages we migrated to. > > While the change here looks funny I think the final code is better. Agree, but I think that either needs to be noted in the changelog so it's not a surprise, or moved to a follow-on cleanup patch.