Re: [PATCH v8 11/15] khugepaged: allow madvise_collapse to check all anonymous mTHP orders

[Andrew Morton]

On Fri, 4 Jul 2025 14:11:13 +0800 Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> wrote:

> On 2025/7/2 13:57, Nico Pache wrote:
> > Allow madvise_collapse to scan/collapse all mTHP orders without the
> > strict requirement of needing the PMD-order enabled.
> > 
> > Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
> 
> I am afraid we should drop this patch from the series, since Hugh 
> explicitly opposed my modification of the madvise_collapse control logic 
> in this thread[1].

Well it drops easily enough.  I don't know if it compiles yet.

Nico, can you confirm that you're OK with the droppage and that the
series is still good without this patch?

> Moreover, since we have not yet clarified how to handle the conflict 
> between the semantics of madvise_collapse and the THP interfaces, we 
> should keep the current logic[2] (means madvise_collapse still only 
> allows PMD collapse).
> 
> If madvise_collapse is to support mTHP collapse, there will be more 
> semantic conflicts to discuss.
> 
> [1] 
> https://lore.kernel.org/all/cover.1750815384.git.baolin.wang@xxxxxxxxxxxxxxxxx/
> [2] 
> https://lore.kernel.org/all/23b8ad10-cd1f-45df-a25c-78d01c8af44f@xxxxxxxxxx/