linux-kernel - Re: [PATCH v3] x86/resctrl: Annotate get_mem_config() functions as _

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Message-ID: <2deb3b0c-121c-4dfb-9179-e919582f5bb4@intel.com>
Date: Thu, 19 Sep 2024 14:15:34 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Nathan Chancellor <nathan@...nel.org>, Fenghua Yu <fenghua.yu@...el.com>,
	<x86@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar
	<mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>
CC: <linux-kernel@...r.kernel.org>, <llvm@...ts.linux.dev>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v3] x86/resctrl: Annotate get_mem_config() functions as
 __init



On 9/17/24 9:02 AM, Nathan Chancellor wrote:
> After a recent LLVM change [1] that deduces __cold on functions that
> only call cold code (such as __init functions), there is a section
> mismatch warning from __get_mem_config_intel(), which got moved to
> .text.unlikely. as a result of that optimization:
> 
>   WARNING: modpost: vmlinux: section mismatch in reference: __get_mem_config_intel+0x77 (section: .text.unlikely.) -> thread_throttle_mode_init (section: .init.text)
> 
> Mark __get_mem_config_intel() as __init as well since it is only called
> from __init code, which clears up the warning.
> 
> While __rdt_get_mem_config_amd() does not exhibit a warning because it
> does not call any __init code, it is a similar function that is only
> called from __init code like __get_mem_config_intel(), so mark it __init
> as well to keep the code symmetrical.
> 
> Link: https://github.com/llvm/llvm-project/commit/6b11573b8c5e3d36beee099dbe7347c2a007bf53 [1]
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> ---

If there is a re-spin I think appropriate Fixes tags can be added:
Fixes: 05b93417ce5b ("x86/intel_rdt/mba: Add primary support for Memory Bandwidth Allocation (MBA)")
Fixes: 4d05bf71f157 ("x86/resctrl: Introduce AMD QOS feature") 

I am not familiar with stable rules related to compiler impact but
this may fall into the "it bothers people" category of fixes so
a Cc: stable@...r.kernel.org sounds appropriate also.

Reinette