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[209.85.220.41]) by mx.google.com with SMTPS id d16sor1524431edj.5.2019.04.20.09.30.26 for (Google Transport Security); Sat, 20 Apr 2019 09:30:26 -0700 (PDT) Received-SPF: pass (google.com: domain of pasha.tatashin@soleen.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@soleen.com header.s=google header.b=M1iwu9ox; spf=pass (google.com: domain of pasha.tatashin@soleen.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=RZD2TOJdguYske3XdmnLmIq3XfcXZwBSYG0QJWjhaWk=; b=M1iwu9oxwvEKXc+QWcLRm6hRiQ5kUxXpfVx34XcRBUZhoRcClhsh0JUyIwC1Ht03If 8a3G+pXgKZ9eavm0LjqGnf1JevmNy/hEoTi1kNvr/hT7CU/N9lh/wstJca1903j3q879 zWvJI/IPpJUKqLRCxvH5qRHYbnBDUKQy+AlS8GyhCyUN0nTH4Fd/1S7KmPnCYG9mSn28 2gQna42o0dUnhv0WrZf4ZmljAB7Iz/0ANS5d32EYaSbcFqdniC2v+w89Yc+/qAuk6ELQ gBYuclDgpS0azcJCu6eTr5cKRx2t41QOMFBfPxhgW4g9bkAA2N/pCgS01Ui1P8Lw52Gu bixQ== X-Google-Smtp-Source: APXvYqyvovu6cFSV63PCP8G4i0thnTzgWZNHajiZGvrLh8glESaAwS8yzV/gVTNrN+wbgH9aZrQzqv2Ey0SevBe6Nm8= X-Received: by 2002:a50:a4e4:: with SMTP id x33mr6290803edb.61.1555777825844; Sat, 20 Apr 2019 09:30:25 -0700 (PDT) MIME-Version: 1.0 References: <20190420153148.21548-1-pasha.tatashin@soleen.com> <20190420153148.21548-3-pasha.tatashin@soleen.com> In-Reply-To: From: Pavel Tatashin Date: Sat, 20 Apr 2019 12:30:14 -0400 Message-ID: Subject: Re: [v1 2/2] device-dax: "Hotremove" persistent memory that is used like normal RAM To: Dan Williams Cc: James Morris , Sasha Levin , Linux Kernel Mailing List , Linux MM , linux-nvdimm , Andrew Morton , Michal Hocko , Dave Hansen , Keith Busch , Vishal L Verma , Dave Jiang , Ross Zwisler , Tom Lendacky , "Huang, Ying" , Fengguang Wu , Borislav Petkov , Bjorn Helgaas , Yaowei Bai , Takashi Iwai , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= 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: > > + > > + /* Walk and offline every singe memory_block of the dax region. */ > > + lock_device_hotplug(); > > + rc = walk_memory_range(start_pfn, end_pfn, dev, offline_memblock_cb); > > + unlock_device_hotplug(); > > + if (rc) > > + return rc; > > This potential early return is the reason why memory hotremove is not > reliable vs the driver-core. If this walk fails to offline the memory > it will still be online, but the driver-core has no consideration for > device-unbind failing. The ubind will proceed while the memory stays > pinned. Hi Dan, Thank you for looking at this. Are you saying, that if drv.remove() returns a failure it is simply ignored, and unbind proceeds? Pasha