Re: [PATCH 1/1] mm/huge_memory: fix pgtable withdrawal for huge zero PMDs

[Andrew Morton]

On Mon, 14 Sep 2026 16:29:00 +0200 "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:

> On 9/14/26 12:59, Kiryl Shutsemau wrote:
> > On Sun, Sep 13, 2026 at 03:23:12PM +0800, Lance Yang wrote:
> >>
> >> On Sat, Sep 12, 2026 at 11:46:35PM -0700, Andrew Morton wrote:
> >>>
> >>>
> >>> That's the sort of thing we'd prefer to avoid.
> >>>
> >>>
> >>> How real is this?  Is there a reported-by:?  Do you have a reproducer? 
> >>
> >> Yes, I reproduced it on x86 with a small test module. It sets
> >> VM_MIXEDMAP | VM_HUGEPAGE and calls vmf_insert_pfn_pmd() with
> >> huge_zero_pfn, without touching the page tables directly. A full-PMD
> >> munmap() crashes before the split series[1] as well.
> > 
> > Ah. So there's no real bug upstream, right?
> 
> Matches my understanding.

Thanks.  I'll remove cc:stable, move this into mm-unstable as a
next-merge-window thing.