Re: [PATCH v2 1/5] prctl: extend PR_SET_THP_DISABLE to optionally exclude VM_HUGEPAGE

[David Hildenbrand]

On 31.07.25 15:12, Usama Arif wrote:
> On 31/07/2025 13:40, Lorenzo Stoakes wrote:
> > On Thu, Jul 31, 2025 at 01:27:18PM +0100, Usama Arif wrote:
> > [snip]
> > > Acked-by: Usama Arif <usamaarif642@xxxxxxxxx>
> > > Tested-by: Usama Arif <usamaarif642@xxxxxxxxx>
> > > Cc: Jonathan Corbet <corbet@xxxxxxx>
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> > > Cc: Zi Yan <ziy@xxxxxxxxxx>
> > > Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> > > Cc: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> > > Cc: Nico Pache <npache@xxxxxxxxxx>
> > > Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
> > > Cc: Dev Jain <dev.jain@xxxxxxx>
> > > Cc: Barry Song <baohua@xxxxxxxxxx>
> > > Cc: Vlastimil Babka <vbabka@xxxxxxx>
> > > Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> > > Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > > Cc: Michal Hocko <mhocko@xxxxxxxx>
> > > Cc: Usama Arif <usamaarif642@xxxxxxxxx>
> > > Cc: SeongJae Park <sj@xxxxxxxxxx>
> > > Cc: Jann Horn <jannh@xxxxxxxxxx>
> > > Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > > Cc: Yafang Shao <laoar.shao@xxxxxxxxx>
> > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> >
> > You don't need to include these Cc's, Andrew will add them for you.
> >
> > > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> > > Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> >
> > Shouldn't this also be signed off by you? 2/5 and 3/5 has S-o-b for both
> > David and yourself?
> >
> > This is inconsistent at the very least.
>
> Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx>
>
> The Ccs were added by David, and I didn't want to remove them.

They were still part of the first submission without cover letter, so 
you should drop them from here now that you are sending it as part of a 
series.

> > > ---
> >
> > Nothing below the --- will be included in the patch, so we can drop the
> > below, it's just noise that people can find easily if needed.
> >
> > > At first, I thought of "why not simply relax PR_SET_THP_DISABLE", but I
> > > think there might be real use cases where we want to disable any THPs --
> > > in particular also around debugging THP-related problems, and
> > > "never" not meaning ... "never" anymore ever since we add MADV_COLLAPSE.
> > > PR_SET_THP_DISABLE will also block MADV_COLLAPSE, which can be very
> > > helpful for debugging purposes. Of course, I thought of having a
> > > system-wide config option to modify PR_SET_THP_DISABLE behavior, but
> > > I just don't like the semantics.
> >
> > [snip]
> >
> > > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> >
> > This S-o-b is weird, it's in a comment essentially. Let's drop that too
> > please.

That just got added automatically while modifying the patch.

> Everything below --- was added by David I believe to provide further explanation that
> doesn't need to be included in the commit message, and I didn't want to remove it
> or his 2nd sign-off, as its discarded anyways. Its useful info that can just be
> ignored.


Best to drop under the "---" I think it was most important for the PoC 
to give more context.


--
Cheers,

David / dhildenb