Re: [PATCH v4 3/9] mm: pagewalk: Don't split transhuge pmds when a pmd_entry is present

From: Thomas HellstrÃm (VMware)
Date: Wed Oct 09 2019 - 13:03:31 EST

On 10/9/19 6:21 PM, Linus Torvalds wrote:
On Wed, Oct 9, 2019 at 8:27 AM Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote:
Do we have any current user that expect split_huge_pmd() in this scenario.
No. There are no current users of the pmd callback and the pte
callback at all, that I could find.

But it looks like the new drm use does want a "I can't handle the
hugepage, please split it and I'll fo the ptes instead".

Nope, it handles the hugepages by ignoring them, since they should be read-only, but if pmd_entry() was called with something else than a hugepage, then it requests the fallback, but never a split.