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[209.85.220.65]) by mx.google.com with SMTPS id c17sor1622880otk.82.2019.06.28.11.59.30 for (Google Transport Security); Fri, 28 Jun 2019 11:59:30 -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=w73nxePK; 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=xZKi8dPs5bce5TA+lDYDR67LZgo76bXK/epIzKFvivc=; b=w73nxePK59nSfEruxrF1M0kHpQTfXV+T0BR3rvgPNUWzxDsJQPeaM7uFD7eKRrxE9Y 9ImwGmBtt6yXJ6nlctHx0FbYi1ua/8g/5ZblEqYZrPEU8IkQx9AAwyacMH73KkUPSZW4 2CnxLw8FBn5LZR6QuLzXXkPegk+n9WnVTkvOy7EQwUeDTJ/KqrjyTyioxg0mlKF5l5Fl pBgbtoepm7/tvV+XTP8uNL6F6V5682w/nGp9yu+fmrqAAOl3CXi6A8E63DaUmygnIHBK Lo3TxfO9CsdVEHmVkApvqnki+XHSFnPPV047Ep963nO0SUi6VwELdrivAHXWP8JUXEYH XM8g== X-Google-Smtp-Source: APXvYqxUAlE0PhQVf+kI2qGh3xwcV/BdcPGn6HCqEnYJmqo0MIx4gI+EfnCAuColBmsblnHh366HyPqaX1Z8NdWYLok= X-Received: by 2002:a9d:7a8b:: with SMTP id l11mr8858325otn.247.1561748370285; Fri, 28 Jun 2019 11:59:30 -0700 (PDT) MIME-Version: 1.0 References: <20190626122724.13313-1-hch@lst.de> <20190626122724.13313-17-hch@lst.de> <20190628153827.GA5373@mellanox.com> <20190628170219.GA3608@mellanox.com> <20190628182922.GA15242@mellanox.com> <20190628185152.GA9117@lst.de> In-Reply-To: <20190628185152.GA9117@lst.de> From: Dan Williams Date: Fri, 28 Jun 2019 11:59:19 -0700 Message-ID: Subject: Re: [PATCH 16/25] device-dax: use the dev_pagemap internal refcount To: Christoph Hellwig Cc: Jason Gunthorpe , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Ben Skeggs , "linux-mm@kvack.org" , "nouveau@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" , "linux-nvdimm@lists.01.org" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Andrew Morton 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 Fri, Jun 28, 2019 at 11:52 AM Christoph Hellwig wrote: > > On Fri, Jun 28, 2019 at 11:44:35AM -0700, Dan Williams wrote: > > There is a problem with the series in CH's tree. It removes the > > ->page_free() callback from the release_pages() path because it goes > > too far and removes the put_devmap_managed_page() call. > > release_pages only called put_devmap_managed_page for device public > pages. So I can't see how that is in any way a problem. It's a bug that the call to put_devmap_managed_page() was gated by MEMORY_DEVICE_PUBLIC in release_pages(). That path is also applicable to MEMORY_DEVICE_FSDAX because it needs to trigger the ->page_free() callback to wake up wait_on_var() via fsdax_pagefree(). So I guess you could argue that the MEMORY_DEVICE_PUBLIC removal patch left the original bug in place. In that sense we're no worse off, but since we know about the bug, the fix and the patches have not been applied yet, why not fix it now?