Re: [PATCH 2/2] fuse: Adjust readdir() buffer to requesting buffer size.

[Bernd Schubert]

On 4/2/25 10:52, Jaco Kroon wrote:
> Hi,
> 
> On 2025/04/02 10:18, Miklos Szeredi wrote:
>> On Wed, 2 Apr 2025 at 09:55, Jaco Kroon <jaco@xxxxxxxxx> wrote:
>>> Hi,
>>>
>>> I can definitely build on that, thank you.
>>>
>>> What's the advantage of kvmalloc over folio's here, why should it be
>>> preferred?
>> It offers the best of both worlds: first tries plain malloc (which
>> just does a folio alloc internally for size > PAGE_SIZE) and if that
>> fails, falls back to vmalloc, which should always succeed since it
>> uses order 0 pages.
> 
> So basically assigns the space, but doesn't commit physical pages for
> the allocation, meaning first access will cause a page fault, and single
> page allocation at that point in time?  Or is it merely the fact that
> vmalloc may return a virtual contiguous block that's not physically
> contiguous?


Yes vmalloc return buffers might not be physically contiguous - not
suitable for hardware DMA. And AFAIK it is also a blocking allocation.


Bernd