On Thu, Sep 01, 2022 at 09:21:19AM +0200, David Hildenbrand wrote: > commit 4b471e8898c3 ("mm, thp: remove infrastructure for handling splitting > PMDs") didn't remove all details about the THP split requirements for > RCU GUP-fast. > > IPI broeadcasts on THP split are no longer required. > > Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Sasha Levin <sasha.levin@xxxxxxxxxx> > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > Cc: Vlastimil Babka <vbabka@xxxxxxx> > Cc: Jerome Marchand <jmarchan@xxxxxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Cc: Hugh Dickins <hughd@xxxxxxxxxx> > Cc: Jason Gunthorpe <jgg@xxxxxxxxxx> > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > Cc: Peter Xu <peterx@xxxxxxxxxx> > Cc: Yang Shi <shy828301@xxxxxxxxx> > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> > --- > mm/gup.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) The comment a bit above seems to need touching to: * protected from page table pages being freed from under it, and should * block any THP splits. What is the current situation for THP splits anyhow? Is there are comment in the fast pmd code explaining it? But this seems OK too Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason