Re: [PATCH] mm/vma: check retry_merge only for new vma case

[Wei Yang <richard.weiyang@gmail.com>]

On Sun, Nov 17, 2024 at 10:56:55PM -0500, Liam R. Howlett wrote:
>* Wei Yang <richard.weiyang@gmail.com> [241117 21:21]:
>> Current code logic looks like this:
>> 
>> __mmap_region()
>>   vma = vma_merge_new_range(&vmg)
>>   if (!vma)
>>     __mmap_new_vma(&map, &vma)
>>       __mmap_new_file_vma(map, vma)
>>         map->retry_merge = xxx               --- (1)
>>   if (map.retry_merge)
>>     vma_merge_existing_range(vmg, &map, vma)
>
>Please don't quote code in your commit log.  We can see the code in the
>diff section.
>

Sure, maybe I misunderstand Lorenzo's suggestion in pre-previous review.

Will not add these in change log in the future.

>> 
>> Location (1) is the only place where map.retry_merge is set, this means
>> it is not necessary to check it if already merged with adjacent vma.
>> 
>> Let's move the check and following operation into new vma case.
>
>This makes sense, but this is a complex block of code.
>
>I'm all for optimisations, but there is already a bug in the code that
>you relocated in your patch, and the backport of these changes isn't
>even complete.
>
>Maybe we can give the existing code some time to soak before optimising?
>

Sure, when is a proper time to re-send it if everything is fine?


-- 
Wei Yang
Help you, Help me