Re: [REGRESSION] mremap() fails VMA expansion when VM_MIXEDMAP is set

[Lorenzo Stoakes (ARM)]

On Fri, Oct 23, 2026 at 09:16:12AM +0200, Vlastimil Babka (SUSE) wrote:
> On 10/23/26 04:31, Luiz Capitulino wrote:

> > This regression was introduced in v6.1 by commit ca3d76b0aa80 ("mm: add merging
> > after mremap resize"). This commit changed mremap() to use vma_merge() instead
> > of vma_adjust() for the expansion case. However, vma_merge() returns NULL for
> > a VMA that has any of the VM_SPECIAL flags set.
>
> Hi,
>
> 6.1 was a rather long time ago. How was it discovered just now? I.e. what
> use case broke by the change and prompted creating the reproducer?
>
> Vlastimil
> Thanks,

Thanks, I have the same questions :)

Do always include that kind of information and whether it was an LLM-discovered
thing or whether you had an actual workload that was impacted, etc.

--
Cheers, Lorenzo