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Tue, 13 Feb 2024 07:32:26 +0100 (CET) Date: Tue, 13 Feb 2024 07:32:26 +0100 From: Lukas Wunner To: Mathieu Desnoyers Cc: Dan Williams , Arnd Bergmann , Dave Chinner , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds , Vishal Verma , Dave Jiang , Matthew Wilcox , Russell King , linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, dm-devel@lists.linux.dev, nvdimm@lists.linux.dev, linux-s390@vger.kernel.org Subject: Re: [PATCH v5 1/8] dax: alloc_dax() return ERR_PTR(-EOPNOTSUPP) for CONFIG_DAX=n Message-ID: <20240213063226.GA4740@wunner.de> References: <20240212163101.19614-1-mathieu.desnoyers@efficios.com> <20240212163101.19614-2-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240212163101.19614-2-mathieu.desnoyers@efficios.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: 9rog4ri6yw5guernf84fr6bosqacx5bs X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 39EEF120008 X-Rspam-User: X-HE-Tag: 1707805947-720526 X-HE-Meta: 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 gM/mpHby CSOCCjNZKFVBBcMetFcG0PWRUffXe116Ut0spM17T/tuYgQd9QtJwILmuvp1cnEBKed2JgotdKbmWRLuvPAIzaa9hvdJFFSUcSr9qbV2tS3D7GWOSKXMy2WIgMmJJiEII3qtLg2CUfzedKcwKD+RunZYC6sVmX7uPKUAV+WsKBk8cvesnkYzlDXjBAn4HlqU3UMFVZy12XDqKFx3G1zFk6Gu0CiraXHDHJMn/xcoVmuMeQ5CJQs5DWNhFLpaAlPk7t4pZ09B34VnIPSgrefrhcTZr7C4CcfRWh4YQ 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: List-Subscribe: List-Unsubscribe: On Mon, Feb 12, 2024 at 11:30:54AM -0500, Mathieu Desnoyers wrote: > Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for > CONFIG_DAX=n to be consistent with the fact that CONFIG_DAX=y > never returns NULL. All the callers of alloc_dax() only check for IS_ERR(). Doesn't this result in a change of behavior in all the callers? Previously they'd ignore the NULL return value and continue, now they'll error out. Given that, seems dangerous to add a Fixes tag with a v4.0 commit and thus risk regressing all stable kernels. Thanks, Lukas