Re: [PATCH] mm: shmem: fix too little space for tmpfs only fallback 4KB

[Vernon Yang]

> On Sep 9, 2025, at 07:22, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> On Mon,  8 Sep 2025 20:31:28 +0800 Vernon Yang <vernon2gm@xxxxxxxxx> wrote:
> 
>> From: Vernon Yang <yanglincheng@xxxxxxxxxx>
>> 
>> When the system memory is sufficient, allocating memory is always
>> successful, but when tmpfs size is low (e.g. 1MB), it falls back
>> directly from 2MB to 4KB, and other small granularity (8KB ~ 1024KB)
>> will not be tried.
>> 
>> Therefore add check whether the remaining space of tmpfs is sufficient
>> for allocation. If there is too little space left, try smaller large
>> folio.
> 
> Thanks.
> 
> What are the effects of this change?  I'm assuming it's an
> *improvement*, rather than a fix for some misbehavior?
> 

When we use tmpfs and the tmpfs space is getting smaller and smaller 
(e.g. less than 2MB), it can still allocate 8KB~1MB large folio.

Thank you for your feedback.