The patch titled Subject: mm/rmap: reject hugetlb folios in folio_make_device_exclusive() has been added to the -mm mm-unstable branch. Its filename is mm-rmap-reject-hugetlb-folios-in-folio_make_device_exclusive.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: David Hildenbrand david@redhat.com Subject: mm/rmap: reject hugetlb folios in folio_make_device_exclusive() Date: Mon, 10 Feb 2025 20:37:44 +0100

Even though FOLL_SPLIT_PMD on hugetlb now always fails with -EOPNOTSUPP, let's add a safety net in case FOLL_SPLIT_PMD usage would ever be reworked.

In particular, before commit 9cb28da54643 ("mm/gup: handle hugetlb in the generic follow_page_mask code"), GUP(FOLL_SPLIT_PMD) would just have returned a page. In particular, hugetlb folios that are not PMD-sized would never have been prone to FOLL_SPLIT_PMD.

hugetlb folios can be anonymous, and page_make_device_exclusive_one() is not really prepared for handling them at all. So let's spell that out.

Link: https://lkml.kernel.org/r/20250210193801.781278-3-david@redhat.com Fixes: b756a3b5e7ea ("mm: device exclusive memory access") Signed-off-by: David Hildenbrand david@redhat.com Reviewed-by: Alistair Popple apopple@nvidia.com Cc: Alex Shi alexs@kernel.org Cc: Danilo Krummrich dakr@kernel.org Cc: Dave Airlie airlied@gmail.com Cc: Jann Horn jannh@google.com Cc: Jason Gunthorpe jgg@nvidia.com Cc: Jerome Glisse jglisse@redhat.com Cc: John Hubbard jhubbard@nvidia.com Cc: Jonathan Corbet corbet@lwn.net Cc: Karol Herbst kherbst@redhat.com Cc: Liam Howlett liam.howlett@oracle.com Cc: Lorenzo Stoakes lorenzo.stoakes@oracle.com Cc: Lyude lyude@redhat.com Cc: "Masami Hiramatsu (Google)" mhiramat@kernel.org Cc: Oleg Nesterov oleg@redhat.com Cc: Pasha Tatashin pasha.tatashin@soleen.com Cc: Peter Xu peterx@redhat.com Cc: Peter Zijlstra (Intel) peterz@infradead.org Cc: SeongJae Park sj@kernel.org Cc: Simona Vetter simona.vetter@ffwll.ch Cc: Vlastimil Babka vbabka@suse.cz Cc: Yanteng Si si.yanteng@linux.dev Cc: Barry Song v-songbaohua@oppo.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/rmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/rmap.c~mm-rmap-reject-hugetlb-folios-in-folio_make_device_exclusive +++ a/mm/rmap.c @@ -2499,7 +2499,7 @@ static bool folio_make_device_exclusive( * Restrict to anonymous folios for now to avoid potential writeback * issues. */ - if (!folio_test_anon(folio)) + if (!folio_test_anon(folio) || folio_test_hugetlb(folio)) return false;

rmap_walk(folio, &rwc); _

Patches currently in -mm which might be from david@redhat.com are

mm-gup-reject-foll_split_pmd-with-hugetlb-vmas.patch mm-rmap-reject-hugetlb-folios-in-folio_make_device_exclusive.patch mm-rmap-convert-make_device_exclusive_range-to-make_device_exclusive.patch mm-rmap-implement-make_device_exclusive-using-folio_walk-instead-of-rmap-walk.patch mm-memory-detect-writability-in-restore_exclusive_pte-through-can_change_pte_writable.patch mm-use-single-swp_device_exclusive-entry-type.patch mm-page_vma_mapped-device-exclusive-entries-are-not-migration-entries.patch kernel-events-uprobes-handle-device-exclusive-entries-correctly-in-__replace_page.patch mm-ksm-handle-device-exclusive-entries-correctly-in-write_protect_page.patch mm-rmap-handle-device-exclusive-entries-correctly-in-try_to_unmap_one.patch mm-rmap-handle-device-exclusive-entries-correctly-in-try_to_migrate_one.patch mm-rmap-handle-device-exclusive-entries-correctly-in-page_vma_mkclean_one.patch mm-page_idle-handle-device-exclusive-entries-correctly-in-page_idle_clear_pte_refs_one.patch mm-damon-handle-device-exclusive-entries-correctly-in-damon_folio_young_one.patch mm-damon-handle-device-exclusive-entries-correctly-in-damon_folio_mkold_one.patch mm-rmap-keep-mapcount-untouched-for-device-exclusive-entries.patch mm-rmap-avoid-ebusy-from-make_device_exclusive.patch