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From: Kent Overstreet To: ranxiaokai627@163.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, corbet@lwn.net, david@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, mhocko@suse.com, ran.xiaokai@zte.com.cn, rppt@kernel.org, surenb@google.com, vbabka@suse.cz Subject: Re: [PATCH] alloc_tag: remove sysctl prefix from mem_profiling boot parameter Message-ID: References: <20260113032735.161838-1-ranxiaokai627@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260113032735.161838-1-ranxiaokai627@163.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: A32CE180005 X-Rspamd-Server: rspam06 X-Stat-Signature: 9wogaodugd5gp6i89onxht1d7a9p9tpi X-Rspam-User: X-HE-Tag: 1768276216-846749 X-HE-Meta: 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 yYbieCBA VGZZpLhOFp0ZjFnPqx1tFtLnQXbiuSnw9nj0vCyCBlGPON+vRdst+gg++qmnqa1KcDr4pGChcg0ya1kLyFLKw579tg8et9dfUuLCr2kFdV7BXRO5TBvNouOmudvNRd1BwEjxxfpBgstojkIv2mcEgptH9JLwjkeGt9w9UkQ/JK62d2Y299JPIHVxtkSvSa4DKWIarYV41ipDrBbFzSgjakshJPbmjfvCvCn5F2G8Xwrb7EYjOsd4MH6SftpaUqlnisbsjIhk/WjncPOnXUOikaL0Vvb7vYiE9kPflrM2phWd0d8w= 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 Tue, Jan 13, 2026 at 03:27:35AM +0000, ranxiaokai627@163.com wrote: > >On Fri, Jan 09, 2026 at 06:24:19AM +0000, ranxiaokai627@163.com wrote: > >> From: Ran Xiaokai > >> > >> Boot parameters prefixed with "sysctl." are processed separately > >> during the final stage of system initialization via kernel_init()-> > >> do_sysctl_args(). Since mem_profiling support should be parsed > >> in early boot stage, it is unsuitable for centralized handling > >> in do_sysctl_args(). > >> Also, when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, > >> the sysctl.vm.mem_profiling entry is not writable and will cause > >> a warning. To prevent duplicate processing of sysctl.vm.mem_profiling, > >> rename the boot parameter to "mem_profiling". > >> > >> Signed-off-by: Ran Xiaokai > > > >How was this observed/detected? > > Actually no kernel bug or funtional defect was observed through testing. > Via code reading, i found after commit [1], > boot parameters prefixed with sysctl is processed redundantly. When bcachefs was in the kernel, I spent an inordinate amount of time in code reviews trying to convince people that yes, they really do need to be testing their code. Strangely enough, I have never had this issue with project contributors who did not come to the project by way of the kernel community... :)