Commit 6654d289 authored Jul 10, 2024 by David Hildenbrand Committed by Andrew Morton Sep 01, 2024

mm/rmap: cleanup partially-mapped handling in __folio_remove_rmap()

Let's simplify and reduce code indentation.  In the RMAP_LEVEL_PTE case,
we already check for nr when computing partially_mapped.

For RMAP_LEVEL_PMD, it's a bit more confusing.  Likely, we don't need the
"nr" check, but we could have "nr < nr_pmdmapped" also if we stumbled into
the "/* Raced ahead of another remove and an add?  */" case.  So let's
simply move the nr check in there.

Note that partially_mapped is always false for small folios.

No functional change intended.

Link: https://lkml.kernel.org/r/20240710214350.147864-1-david@redhat.com


Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 94ccd21e

mm/rmap.c

+10 −13

Original line number	Diff line number	Diff line
		@@ -1568,22 +1568,19 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
		}
		}

		partially_mapped = nr < nr_pmdmapped;
		partially_mapped = nr && nr < nr_pmdmapped;
		break;
		}

		if (nr) {
		/*
		* Queue anon large folio for deferred split if at least one
		* page of the folio is unmapped and at least one page
		* is still mapped.
		* Queue anon large folio for deferred split if at least one page of
		* the folio is unmapped and at least one page is still mapped.
		*
		* Check partially_mapped first to ensure it is a large folio.
		*/
		if (folio_test_anon(folio) && partially_mapped &&
		if (partially_mapped && folio_test_anon(folio) &&
		list_empty(&folio->_deferred_list))
		deferred_split_folio(folio);
		}
		__folio_mod_stat(folio, -nr, -nr_pmdmapped);

		/*