mm/gup: remove no longer used gup_fast_undo_dev_pagemap

This helper is no longer used after commit fd2825b0760a ("mm/gup: remove
pXX_devmap usage from get_user_pages()").

Link: https://lkml.kernel.org/r/20251219-gup-cleanup-v1-1-348a70d9eecb@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 0 insertions, 11 deletions

diff --git a/mm/gup.c b/mm/gup.c
index 95d948c8e86c..8e7dc2c6ee73 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2806,17 +2806,6 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags)
 	return !reject_file_backed || shmem_mapping(mapping);
 }
 
-static void __maybe_unused gup_fast_undo_dev_pagemap(int *nr, int nr_start,
-		unsigned int flags, struct page **pages)
-{
-	while ((*nr) - nr_start) {
-		struct folio *folio = page_folio(pages[--(*nr)]);
-
-		folio_clear_referenced(folio);
-		gup_put_folio(folio, 1, flags);
-	}
-}
-
 #ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
 /*
  * GUP-fast relies on pte change detection to avoid concurrent pgtable