linux-kernel - Re: [PATCH v18 2/3] mm: memory-failure: move return value documentation to function declaration

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Message-ID: <0c93542f-4521-41bc-a030-5b2d8621aa6a@linux.alibaba.com>
Date: Fri, 28 Feb 2025 09:46:30 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: yazen.ghannam@....com, mark.rutland@....com, mingo@...hat.com,
 robin.murphy@....com, Jonathan.Cameron@...wei.com, bp@...en8.de,
 rafael@...nel.org, linux-arm-kernel@...ts.infradead.org,
 wangkefeng.wang@...wei.com, tanxiaofei@...wei.com, mawupeng1@...wei.com,
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 james.morse@....com, tongtiangen@...wei.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@...ux.alibaba.com, ashish.kalra@....com,
 baolin.wang@...ux.alibaba.com, tglx@...utronix.de,
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 robert.moore@...el.com, lvying6@...wei.com, xiexiuqi@...wei.com,
 zhuo.song@...ux.alibaba.com
Subject: Re: [PATCH v18 2/3] mm: memory-failure: move return value
 documentation to function declaration



在 2025/2/27 20:31, Catalin Marinas 写道:
> (going through patches in my inbox)
> 
> On Tue, Jan 07, 2025 at 04:17:34PM +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
> 
> s/declaration/definition/

Thanks, will fix.

> 
>> 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>
>> Reviewed-by: Yazen Ghannam <yazen.ghannam@....com>
>> Reviewed-by: Jane Chu <jane.chu@...cle.com>
>> ---
>>   arch/x86/kernel/cpu/mce/core.c |  7 -------
>>   mm/memory-failure.c            | 10 +++++++---
>>   2 files changed, 7 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>> index 7fb5556a0b53..d1dd7f892514 100644
>> --- a/arch/x86/kernel/cpu/mce/core.c
>> +++ b/arch/x86/kernel/cpu/mce/core.c
>> @@ -1398,13 +1398,6 @@ 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 a7b8ccd29b6f..14c316d7d38d 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -2211,9 +2211,13 @@ 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,
>> + *   -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)
>>   {
> 
> Why not keep the comment in both places? One is about the x86 decisions,
> the other is about what memory_failure() can return.
> 

Ok, will keep x86 path.

By the way, could arm maintainers help to ack patch 1 and 3 if there
is no objection?

Thanks.
Shuai