Re: [PATCH 0/8] Stop special-casing hugetlb mappings in get_unmapped_area

[Andrew Morton]

On Sat,  6 Jun 2026 05:49:55 +0200 Oscar Salvador <osalvador@xxxxxxx> wrote:

> A regression was reported on AMD 15h Family for hugetlb mappings when 'align_va_addr'
> is set [1].

It would be helpful to say right here that this regression results in a
runtime BUG().  Helps get attention ;)

> Historically, for hugetlb mappings we always ignored 'align_offset' in get_unmapped_area
> functions, but after commit 7bd3f1e1a9ae ("mm: make hugetlb mappings go through
> mm_get_unmapped_area_vmflags") that was no longer the case for x86.
> 
> While we could fix that by work it around in x86 code, the truth is that the current
> functioning of hugetlb mappings with get_unmapped_area functions is a bit clumsy, and
> we can do better.
> This patchset aims at two things:
> 
> 1) Fix regression reported in [1]
> 2) Stop special-casing hugetlb mappings in get_unmapped_area functions

OK, so the offending commit was about 1.5 years ago.

Do we want to fix -stable kernels?  If so, can we start out with
something minimal for backporting?  And narrow down its Fixes:?

The series was sent at an awkward time in the -rc cycle, which perhaps
explains the lack of feedback.  I suggest a refresh/retest/resend to
help bring people up to speed.

Sashiko has quite a lot to say - I hope some of it is useful?
	https://sashiko.dev/#/patchset/20260606035003.529685-1-osalvador@xxxxxxx