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[209.85.220.65]) by mx.google.com with SMTPS id g11sor9892301jao.13.2019.06.04.01.50.50 for (Google Transport Security); Tue, 04 Jun 2019 01:50:50 -0700 (PDT) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=s+BZYPLT; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=T3hHFGqrMn1+Csc7ogJAJELfMmtCK4b/mNGsWqPXMSs=; b=s+BZYPLTRv9v6rWK+5uRT0LvtuHd27GSQqarKWyjG4BSEOqHjud5FUNVi/8iI3dkem 9Drf+GABFNUsxGyrX+qJXJWnu/vozq02OmSZ1BqWSkOcGYhR/roexxgha4TMNMFN1zYM VaFgUnwre/5yA0nUzztImy0YlNyFGjXOQPgWh25UqIjKz+XRbjHig/+sxfaP/NSrhIUO CRUJhlPJ2y0QEOm4de4tNcGrXeYX3diaMyzQcIDusACY4/IB7o6U1cHfAdwJDfart49j 3w0dS2vtWAZu0qsYojxtpJUZr0SrVK9caR49lxGzFz7ekq4VDcmmoTu9Fl5ALhw3GcoQ j4xQ== X-Google-Smtp-Source: APXvYqw2d+Pigp+yuoJfD957oHtsC9aPSPUuB2VxrEocEVkZT5Yq3MSS4N88NNppLN6LiDVtF65M6ErW0QGe0lmhFo4= X-Received: by 2002:a02:5489:: with SMTP id t131mr18326627jaa.70.1559638250407; Tue, 04 Jun 2019 01:50:50 -0700 (PDT) MIME-Version: 1.0 References: <1559633160-14809-1-git-send-email-kernelfans@gmail.com> In-Reply-To: From: Pingfan Liu Date: Tue, 4 Jun 2019 16:50:39 +0800 Message-ID: Subject: Re: [PATCH] mm/gup: remove unnecessary check against CMA in __gup_longterm_locked() To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, Andrew Morton , Ira Weiny , Dan Williams , Thomas Gleixner , Mike Rapoport , John Hubbard , Keith Busch , LKML 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 Tue, Jun 4, 2019 at 4:30 PM Aneesh Kumar K.V wrote: > > On 6/4/19 12:56 PM, Pingfan Liu wrote: > > The PF_MEMALLOC_NOCMA is set by memalloc_nocma_save(), which is finally > > cast to ~_GFP_MOVABLE. So __get_user_pages_locked() will get pages from > > non CMA area and pin them. There is no need to > > check_and_migrate_cma_pages(). > > > That is not completely correct. We can fault in that pages outside > get_user_pages_longterm at which point those pages can get allocated > from CMA region. memalloc_nocma_save() as added as an optimization to > avoid unnecessary page migration. Yes, you are right. Thanks, Pingfan