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From: Kent Overstreet <kent.overstreet@linux.dev>
To: ranxiaokai627@163.com
Cc: surenb@google.com, vbabka@suse.cz, akpm@linux-foundation.org, 
	david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, 
	rppt@kernel.org, mhocko@suse.com, corbet@lwn.net, linux-mm@kvack.org, 
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, ran.xiaokai@zte.com.cn
Subject: Re: [PATCH] alloc_tag: remove sysctl prefix from mem_profiling boot
 parameter
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References: <20260109062419.157284-1-ranxiaokai627@163.com>
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On Fri, Jan 09, 2026 at 06:24:19AM +0000, ranxiaokai627@163.com wrote:
> From: Ran Xiaokai <ran.xiaokai@zte.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@zte.com.cn>

How was this observed/detected?

My reading of early_param() would seem to indicate that
setup_early_mem_profiling() is getting called at the appropriate time -
and then additionally a second time by do_sysctl_args(), which then
becomes a noop.

So the only bug would seem to be that the sysctl is not writeable in
debug mode? There's an easier fix for that one...