Re: [PATCH 01/10] selftests/mm: exercise MADV_COLD and MADV_PAGEOUT

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

On Wed, Sep 23, 2026 at 10:44:17AM -0400, Gregory Price wrote:
> On Wed, Sep 23, 2026 at 03:26:05PM +0100, Lorenzo Stoakes (ARM) wrote:
> >
> > I think in general we want to avoid putting stress tests as part of the
> > selftests in general? Or at least if they might take a long time to run or
> > excessive memory usage, etc.
> >
> > Though that might be benchmarks, as we have the THP stress tests so maybe it's
> > OK?
> >
> > >
> > > Assisted-by: LLM
> > > Signed-off-by: Gregory Price (Meta) <gourry@gourry.net>
> >
> > In any case I really do think this should be split out into smaller parts, this
> > is a _gigantic_ change :)
> >
>
> Absolutely, but alas my poor email hosting throttles me if i send too
> many emails - and sending a 38-part series where the important part is
> the endpoint of the refactor moreso than the individual tests...
> instant 24-hour timeout.
>
> I'm working on a solution.  Need better hosting.

Thanks! But yeah damn indeed you do! :)

Though larger series can scare people off so maybe better to send the tests
separately?

>
> > Since you list a whole bunch of different test areas and you're exercising
> > different things you should be able to split this out logically across those I
> > think?
>
> As mentioned, this was originally ~28 patches split out, but i think
> ultimately only the contractual tests should be shipped.
>
> Maybe there's an argument for keeping some of the implementation
> details - they're fairly easy to find in the code below for individual
> inspection.
>
> Examples
>
> contractual: These tests won't change behavior based on implementation
>  - authorized file PAGEOUT evicts a clean file page;
>  - unauthorized shared-file PAGEOUT leaves the page resident; and
>  - private-file PAGEOUT reclaims a COW page but preserves a file page.
>
> implementation detail: behavior can change without breaking a contract
>  - full and partial MADV_COLD on a PTE-mapped THP

Yeah doesn't sound unreasonable.

>
> ~Gregory

--
Cheers, Lorenzo