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Tue, 13 Jan 2026 08:33:54 -0800 (PST) MIME-Version: 1.0 References: <20260113032735.161838-1-ranxiaokai627@163.com> In-Reply-To: From: Suren Baghdasaryan Date: Tue, 13 Jan 2026 08:33:43 -0800 X-Gm-Features: AZwV_QhF2LNh9b5y9XH-3TUKdD9SDJ16RHoFzZRc-qtc8Hdy1LAoshy7iJbvlXE Message-ID: Subject: Re: [PATCH] alloc_tag: remove sysctl prefix from mem_profiling boot parameter To: Kent Overstreet Cc: ranxiaokai627@163.com, 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, vbabka@suse.cz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 6wqk86hnnf8t63c7gkdgdzqcxn8ka4pe X-Rspamd-Queue-Id: DA997100016 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1768322035-217707 X-HE-Meta: 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 zrQXoonN 1jPGbK2kJ+lr47ooGSlTnbaY7TPguTiPVXNdLKo4kpHZuW7y2eYk2ZT01xSBGFOIE5GRNXrD3PSBgv4LU2HAXsOaMk/hRUI2Ou4/AXQZSJPgzkzWDjHWlbpaRj/Zr3xpVJlk68u4PYfhT395Lr43V+QAgbyMzRSsk2TGqvxlj3qZm3RSn/pmTGO3v6D0BQ2lqr4TEHjfkHCzXrMnzFjDtLyDhdT66gQ7c2mhPvaADxUoJuvKf/39iejGgxnWgdeyjIy6ys+A2AvvBDMELG+Rio0ADMHsQTc06smnnsq9zsn70CQmRFKhjJ2qjOo0Vgj+APEAJ/t0reS5lHZK+Z0A2V4SFvFNHGnegZKIRr4bElZypgRl7EfP2sOAqtA== 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, Jan 12, 2026 at 7:50=E2=80=AFPM Kent Overstreet wrote: > > 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_profilin= g, > > >> 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. I was able to reproduce the warning by enabling CONFIG_MEM_ALLOC_PROFILING, CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, CONFIG_MEM_ALLOC_PROFILING_DEBUG, CONFIG_SYSCTL and setting CONFIG_CMDLINE=3D"1". The fix I posted eliminates that warning. Ran, you can post my suggestion yourself with me as Suggested-by or I can post it with you as Reported-by. Let me know your preference. > > 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... :)