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[140.211.169.12]) by mx.google.com with ESMTPS id u84si4659088pfa.134.2019.03.07.09.46.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Mar 2019 09:46:55 -0800 (PST) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 17DE1C139; Thu, 7 Mar 2019 17:46:55 +0000 (UTC) Date: Thu, 7 Mar 2019 09:46:54 -0800 From: Andrew Morton To: Dan Williams Cc: Jerome Glisse , Linux MM , Linux Kernel Mailing List , Ralph Campbell , John Hubbard , linux-fsdevel Subject: Re: [PATCH 09/10] mm/hmm: allow to mirror vma of a file on a DAX backed filesystem Message-Id: <20190307094654.35391e0066396b204d133927@linux-foundation.org> In-Reply-To: References: <20190129165428.3931-10-jglisse@redhat.com> <20190129193123.GF3176@redhat.com> <20190129212150.GP3176@redhat.com> <20190130030317.GC10462@redhat.com> <20190130183616.GB5061@redhat.com> <20190131041641.GK5061@redhat.com> <20190305141635.8134e310ba7187bc39532cd3@linux-foundation.org> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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, 5 Mar 2019 20:20:10 -0800 Dan Williams wrote: > My hesitation would be drastically reduced if there was a plan to > avoid dangling unconsumed symbols and functionality. Specifically one > or more of the following suggestions: > > * EXPORT_SYMBOL_GPL on all exports to avoid a growing liability > surface for out-of-tree consumers to come grumble at us when we > continue to refactor the kernel as we are wont to do. The existing patches use EXPORT_SYMBOL() so that's a sticking point. Jerome, what would happen is we made these EXPORT_SYMBOL_GPL()? > * A commitment to consume newly exported symbols in the same merge > window, or the following merge window. When that goal is missed revert > the functionality until such time that it can be consumed, or > otherwise abandoned. It sounds like we can tick this box. > * No new symbol exports and functionality while existing symbols go unconsumed. Unsure about this one?