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

[Gregory Price <gourry@gourry.net>]

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.

> 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

~Gregory