[v1,1/6] mm/rmap: drop stale comment in page_add_anon_rmap and hugepage_add_anon_rmap()

Commit Message

David Hildenbrand Sept. 13, 2023, 12:51 p.m. UTC

That comment was added in commit 5dbe0af47f8a ("mm: fix kernel BUG at
mm/rmap.c:1017!") to document why we can see vma->vm_end getting
adjusted concurrently due to a VMA split.

However, the optimized locking code was changed again in bf181b9f9d8
("mm anon rmap: replace same_anon_vma linked list with an interval tree.").

... and later, the comment was changed in commit 0503ea8f5ba7 ("mm/mmap:
remove __vma_adjust()") to talk about "vma_merge" although the original
issue was with VMA splitting.

Let's just remove that comment. Nowadays, it's outdated, imprecise and
confusing.

Signed-off-by: David Hildenbrand <[e-mail]>
---
 mm/rmap.c | 2 --
 1 file changed, 2 deletions(-)

Patch

diff --git a/mm/rmap.c b/mm/rmap.c
index ec7f8e6c9e48..ca2787c1fe05 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1245,7 +1245,6 @@  void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
 		__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
 
 	if (likely(!folio_test_ksm(folio))) {
-		/* address might be in next vma when migration races vma_merge */
 		if (first)
 			__page_set_anon_rmap(folio, page, vma, address,
 					     !!(flags & RMAP_EXCLUSIVE));
@@ -2536,7 +2535,6 @@  void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
 
 	BUG_ON(!folio_test_locked(folio));
 	BUG_ON(!anon_vma);
-	/* address might be in next vma when migration races vma_merge */
 	first = atomic_inc_and_test(&folio->_entire_mapcount);
 	VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);
 	VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);