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[195.135.220.15]) by mx.google.com with ESMTPS id a17si11085826ejt.123.2019.07.26.01.44.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Jul 2019 01:44:09 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 40DBAAD5E; Fri, 26 Jul 2019 08:44:09 +0000 (UTC) Date: Fri, 26 Jul 2019 10:44:08 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org, "Rafael J. Wysocki" , Andrew Morton , Oscar Salvador Subject: Re: [PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init() Message-ID: <20190726084408.GK6142@dhcp22.suse.cz> References: <20190725125636.GA3582@dhcp22.suse.cz> <6dc566c2-faf6-565d-4ef1-2ac3a366bc76@redhat.com> <20190725135747.GB3582@dhcp22.suse.cz> <447b74ca-f7c7-0835-fd50-a9f7191fe47c@redhat.com> <20190725191943.GA6142@dhcp22.suse.cz> <20190726075729.GG6142@dhcp22.suse.cz> <20190726083117.GJ6142@dhcp22.suse.cz> <38d76051-504e-c81a-293a-0b0839e829d3@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <38d76051-504e-c81a-293a-0b0839e829d3@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 26-07-19 10:36:42, David Hildenbrand wrote: > On 26.07.19 10:31, Michal Hocko wrote: [...] > > Anyway, my dislike of the device_hotplug_lock persists. I would really > > love to see it go rather than grow even more to the hotplug code. We > > should be really striving for mem hotplug internal and ideally range > > defined locking longterm. > > Yes, and that is a different story, because it will require major > changes to all add_memory() users. (esp, due to the documented race > conditions). Having that said, memory hotplug locking is not ideal yet. I am really happy to hear that we are on the same page here. Do we have any document (I am sorry but I am lacking behind recent development in this area) that describes roadblocks to remove device_hotplug_lock? -- Michal Hocko SUSE Labs