linux-kernel - Re: [PATCH v1 04/18] mm: track mapcount of large folios in single value

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Date: Thu, 18 Apr 2024 22:50:03 +0800
From: Lance Yang <ioworker0@...il.com>
To: david@...hat.com
Cc: akpm@...ux-foundation.org,
	cgroups@...r.kernel.org,
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Subject: Re: [PATCH v1 04/18] mm: track mapcount of large folios in single value

Hey David,

FWIW, just a nit below.

diff --git a/mm/rmap.c b/mm/rmap.c
index 2608c40dffad..08bb6834cf72 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1143,7 +1143,6 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio,
 		int *nr_pmdmapped)
 {
 	atomic_t *mapped = &folio->_nr_pages_mapped;
-	const int orig_nr_pages = nr_pages;
 	int first, nr = 0;
 
 	__folio_rmap_sanity_checks(folio, page, nr_pages, level);
@@ -1155,6 +1154,7 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio,
 			break;
 		}
 
+		atomic_add(nr_pages, &folio->_large_mapcount);
 		do {
 			first = atomic_inc_and_test(&page->_mapcount);
 			if (first) {
@@ -1163,7 +1163,6 @@ static __always_inline unsigned int __folio_add_rmap(struct folio *folio,
 					nr++;
 			}
 		} while (page++, --nr_pages > 0);
-		atomic_add(orig_nr_pages, &folio->_large_mapcount);
 		break;
 	case RMAP_LEVEL_PMD:
 		first = atomic_inc_and_test(&folio->_entire_mapcount);

Thanks,
Lance