Re: [PATCH v7 03/14] mm: Introduce memfile_notifier

David Hildenbrand
2022-08-10T10:05:52Z

On 10.08.22 11:22, Chao Peng wrote:
> On Fri, Aug 05, 2022 at 03:22:58PM +0200, David Hildenbrand wrote:
>> On 06.07.22 10:20, Chao Peng wrote:
>>> This patch introduces memfile_notifier facility so existing memory file
>>> subsystems (e.g. tmpfs/hugetlbfs) can provide memory pages to allow a
>>> third kernel component to make use of memory bookmarked in the memory
>>> file and gets notified when the pages in the memory file become
>>> invalidated.
>>
>> Stupid question, but why is this called "memfile_notifier" and not
>> "memfd_notifier". We're only dealing with memfd's after all ... which
>> are anonymous files essentially. Or what am I missing? Are there any
>> other plans for fs than plain memfd support that I am not aware of?
>
> There were some discussions on this in v3.
> https://lkml.org/lkml/2021/12/28/484
> Sean commented it's OK to abstract it from memfd but he also wants the
> kAPI (name) should not bind to memfd to make room for future non-memfd
> usages.

Sorry, but how is "memfile" any better? memfd abstracted to memfile?! :)

I understand Sean's suggestion about abstracting, but if the new name
makes it harder to grasp and there isn't really an alternative to memfd
in sight, I'm not so sure I enjoy the tried abstraction here.

Otherwise we'd have to get creative now and discuss something like
"file_population_notifer" or "mapping_population_notifer" and I am not
sure that our time is well spent doing so right now.

... as this is kernel-internal, we can always adjust the name as we
please later, once we *actually* now what the abstraction should be.
Until then I'd suggest to KIS and soft-glue this to memfd.

Or am I missing something important?

--
Thanks,

David / dhildenb