mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]()

Let's convert it like we converted all the other rmap functions.  Don't
introduce folio_try_share_anon_rmap_ptes() for now, as we don't have a
user that wants rmap batching in sight.  Pretty easy to add later.

All users are easy to convert -- only ksm.c doesn't use folios yet but
that is left for future work -- so let's just do it in a single shot.

While at it, turn the BUG_ON into a WARN_ON_ONCE.

Note that page_try_share_anon_rmap() so far didn't care about pte/pmd
mappings (no compound parameter).  We're changing that so we can perform
better sanity checks and make the code actually more readable/consistent. 
For example, __folio_rmap_sanity_checks() will make sure that a PMD range
actually falls completely into the folio.

Link: https://lkml.kernel.org/r/20231220224504.646757-39-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 716e2f87dd79..8c001819cf10 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1331,8 +1331,9 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 			goto out_unlock;
 		}
 
-		/* See page_try_share_anon_rmap(): clear PTE first. */
-		if (anon_exclusive && page_try_share_anon_rmap(page)) {
+		/* See folio_try_share_anon_rmap_pte(): clear PTE first. */
+		if (anon_exclusive &&
+		    folio_try_share_anon_rmap_pte(page_folio(page), page)) {
 			set_pte_at(mm, pvmw.address, pvmw.pte, entry);
 			goto out_unlock;
 		}