linux-kernel - Re: [PATCH v16 2/3] mm: memory-failure: move return value documentation to function declaration

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Message-ID: <20241105151847.GF916505@yaz-khff2.amd.com>
Date: Tue, 5 Nov 2024 10:18:47 -0500
From: Yazen Ghannam <yazen.ghannam@....com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>
Cc: mark.rutland@....com, catalin.marinas@....com, mingo@...hat.com,
	robin.murphy@....com, Jonathan.Cameron@...wei.com, bp@...en8.de,
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	zhuo.song@...ux.alibaba.com
Subject: Re: [PATCH v16 2/3] mm: memory-failure: move return value
 documentation to function declaration

On Mon, Nov 04, 2024 at 09:54:29AM +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>
> Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
>  arch/x86/kernel/cpu/mce/core.c | 7 -------
>  mm/memory-failure.c            | 9 ++++++---
>  2 files changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 2a938f429c4d..c90d8fcd246a 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1373,13 +1373,6 @@ 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;
>  
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 96ce31e5a203..1c5098f32d48 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2209,9 +2209,12 @@ static void kill_procs_now(struct page *p, 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:
> + *   0             - success,

One more obvious one from this function:

	-ENXIO        - memory not managed by the kernel

> + *   -EOPNOTSUPP   - hwpoison_filter() filtered the error event,
> + *   -EHWPOISON    - the page was already poisoned, potentially
> + *                   kill process,
> + *   other negative values - failure.
>   */
>  int memory_failure(unsigned long pfn, int flags)
>  {
> -- 

Reviewed-by: Yazen Ghannam <yazen.ghannam@....com>

Thanks,
Yazen