Subject: linux-next: manual merge of the random tree with the mm-stable tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 2 Jul 2024 16:40:41 +1000

Hi all,

Today's linux-next merge of the random tree got a conflict in:

  mm/rmap.c

between commits:

  a2a1b9f670f3 ("mm/rmap: remove duplicated exit code in pagewalk loop")
  92493c3b92b1 ("mm: extend rmap flags arguments for folio_add_new_anon_rmap")
  db4fb1039a19 ("mm: use folio_add_new_anon_rmap() if folio_test_anon(folio)==false")

from the mm-stable tree and commit:

  e788371a45ac ("mm: add VM_DROPPABLE for designating always lazily freeable mappings")

from the random tree.

I fixed it up (I think - see below) and can carry the fix as
necessary. This is now fixed as far as linux-next is concerned, but any
non trivial conflicts should be mentioned to your upstream maintainer
when your tree is submitted for merging.  You may also want to consider
cooperating with the maintainer of the conflicting tree to minimise any
particularly complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc mm/rmap.c
index 8616308610b9,d873a3f06506..000000000000
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@@ -1394,27 -1384,22 +1394,27 @@@ void folio_add_anon_rmap_pmd(struct fol
   *
   * Like folio_add_anon_rmap_*() but must only be called on *new* folios.
   * This means the inc-and-test can be bypassed.
 - * The folio does not have to be locked.
 + * The folio doesn't necessarily need to be locked while it's exclusive
 + * unless two threads map it concurrently. However, the folio must be
 + * locked if it's shared.
   *
 - * If the folio is pmd-mappable, it is accounted as a THP.  As the folio
 - * is new, it's assumed to be mapped exclusively by a single process.
 + * If the folio is pmd-mappable, it is accounted as a THP.
   */
  void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 -		unsigned long address)
 +		unsigned long address, rmap_t flags)
  {
 -	int nr = folio_nr_pages(folio);
 +	const int nr = folio_nr_pages(folio);
 +	const bool exclusive = flags & RMAP_EXCLUSIVE;
 +	int nr_pmdmapped = 0;
  
  	VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
 +	VM_WARN_ON_FOLIO(!exclusive && !folio_test_locked(folio), folio);
  	VM_BUG_ON_VMA(address < vma->vm_start ||
  			address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
 -	if (!(vma->vm_flags & VM_DROPPABLE))
 +
- 	if (!folio_test_swapbacked(folio))
++	if (!folio_test_swapbacked(folio) && !(vma->vm_flags & VM_DROPPABLE))
  		__folio_set_swapbacked(folio);
 -	__folio_set_anon(folio, vma, address, true);
 +	__folio_set_anon(folio, vma, address, exclusive);
  
  	if (likely(!folio_test_large(folio))) {
  		/* increment count (starts at -1) */
@@@ -1858,8 -1852,11 +1858,9 @@@ static bool try_to_unmap_one(struct fol
  				 * discarded. Remap the page to page table.
  				 */
  				set_pte_at(mm, address, pvmw.pte, pteval);
- 				folio_set_swapbacked(folio);
+ 				if (!(vma->vm_flags & VM_DROPPABLE))
+ 					folio_set_swapbacked(folio);
 -				ret = false;
 -				page_vma_mapped_walk_done(&pvmw);
 -				break;
 +				goto walk_abort;
  			}
  
  			if (swap_duplicate(entry) < 0) {