linux-kernel - Re: [PATCH] alloc_tag: remove sysctl prefix from mem

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Message-ID: <aWXAaiLXn2tXr8nU@moria.home.lan>
Date: Mon, 12 Jan 2026 22:50:06 -0500
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: ranxiaokai627@....com
Cc: Liam.Howlett@...cle.com, akpm@...ux-foundation.org, corbet@....net, 
	david@...nel.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, lorenzo.stoakes@...cle.com, mhocko@...e.com, 
	ran.xiaokai@....com.cn, rppt@...nel.org, surenb@...gle.com, vbabka@...e.cz
Subject: Re: [PATCH] alloc_tag: remove sysctl prefix from mem_profiling boot
 parameter

On Tue, Jan 13, 2026 at 03:27:35AM +0000, ranxiaokai627@....com wrote:
> >On Fri, Jan 09, 2026 at 06:24:19AM +0000, ranxiaokai627@....com wrote:
> >> From: Ran Xiaokai <ran.xiaokai@....com.cn>
> >> 
> >> 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 <ran.xiaokai@....com.cn>
> >
> >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... :)