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mm/rmap: reject hugetlb folios in folio_make_device_exclusive()

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commit bc3fe6805cf09a25a086573a17d40e525208c5d8 upstream.

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 9cb28da546 ("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: b756a3b5e7 ("mm: device exclusive memory access")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Tested-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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Hildenbrand 2025-02-10 20:37:44 +01:00 committed by Greg Kroah-Hartman
parent 36106d1c27
commit aa82be5125
1 changed files with 1 additions and 1 deletions
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2
mm/rmap.c
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@ -2306,7 +2306,7 @@ static bool folio_make_device_exclusive(struct folio *folio,
* 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);