linux-kernel - Re: [PATCH v11 2/3] mm: memory-failure: move return value documentation to function declaration

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Date: Mon, 26 Feb 2024 11:46:11 +0100
From: Borislav Petkov <bp@...en8.de>
To: Shuai Xue <xueshuai@...ux.alibaba.com>
Cc: rafael@...nel.org, wangkefeng.wang@...wei.com, tanxiaofei@...wei.com,
	mawupeng1@...wei.com, tony.luck@...el.com, linmiaohe@...wei.com,
	naoya.horiguchi@....com, james.morse@....com,
	gregkh@...uxfoundation.org, will@...nel.org, jarkko@...nel.org,
	linux-acpi@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	linux-edac@...r.kernel.org, x86@...nel.org, justin.he@....com,
	ardb@...nel.org, ying.huang@...el.com, ashish.kalra@....com,
	baolin.wang@...ux.alibaba.com, tglx@...utronix.de, mingo@...hat.com,
	dave.hansen@...ux.intel.com, lenb@...nel.org, hpa@...or.com,
	robert.moore@...el.com, lvying6@...wei.com, xiexiuqi@...wei.com,
	zhuo.song@...ux.alibaba.com
Subject: Re: [PATCH v11 2/3] mm: memory-failure: move return value
 documentation to function declaration

On Sun, Feb 04, 2024 at 04:01:43PM +0800, Shuai Xue wrote:
> Part of return value comments for memory_failure() were originally
> documented at the call site. Move those comments to the function
> declaration to improve code readability and to provide developers with
> immediate access to function usage and return information.
> 
> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
> ---
>  arch/x86/kernel/cpu/mce/core.c | 9 +--------
>  mm/memory-failure.c            | 9 ++++++---
>  2 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index bc39252bc54f..822b21eb48ad 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1365,17 +1365,10 @@ static void kill_me_maybe(struct callback_head *cb)
>  		return;
>  	}
>  
> -	/*
> -	 * -EHWPOISON from memory_failure() means that it already sent SIGBUS
> -	 * to the current process with the proper error info,
> -	 * -EOPNOTSUPP means hwpoison_filter() filtered the error event,
> -	 *
> -	 * In both cases, no further processing is required.
> -	 */
>  	if (ret == -EHWPOISON || ret == -EOPNOTSUPP)
>  		return;
>  
> -	pr_err("Memory error not recovered");
> +	pr_err("Sending SIGBUS to current task due to memory error not recovered");

Unrelated change.

>  	kill_me_now(cb);
>  }
>  
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 636280d04008..d33729c48eff 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2175,9 +2175,12 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
>   * Must run in process context (e.g. a work queue) with interrupts
>   * enabled and no spinlocks held.
>   *
> - * Return: 0 for successfully handled the memory error,
> - *         -EOPNOTSUPP for hwpoison_filter() filtered the error event,
> - *         < 0(except -EOPNOTSUPP) on failure.
> + * Return values:
> + *   0             - success
> + *   -EOPNOTSUPP   - hwpoison_filter() filtered the error event.
> + *   -EHWPOISON    - sent SIGBUS to the current process with the proper
> + *                   error info by kill_accessing_process().

kill_accessing_process() is not the only one returning -EHWPOISON.

And if you look at the code, it should be:

	-EHWPOISON	- the page was already poisoned, potentially
			kill process

or so.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette