linux-kernel - [PATCH v1 1/2] fs/proc/task_mmu: convert pagemap_hugetlb

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Date: Wed, 17 Apr 2024 11:23:12 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>
Subject: [PATCH v1 1/2] fs/proc/task_mmu: convert pagemap_hugetlb_range() to work on folios

Let's get rid of another page_mapcount() check and simply use
folio_likely_mapped_shared(), which is precise for hugetlb folios.

While at it, also check for PMD table sharing, like we do in
smaps_hugetlb_range().

No functional change intended, except that we would now detect hugetlb
folios shared via PMD table sharing correctly.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 fs/proc/task_mmu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8ff79bd427ec6..cd6e45e0cde8e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1578,12 +1578,13 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 
 	pte = huge_ptep_get(ptep);
 	if (pte_present(pte)) {
-		struct page *page = pte_page(pte);
+		struct folio *folio = page_folio(pte_page(pte));
 
-		if (!PageAnon(page))
+		if (!folio_test_anon(folio))
 			flags |= PM_FILE;
 
-		if (page_mapcount(page) == 1)
+		if (!folio_likely_mapped_shared(folio) &&
+		    !hugetlb_pmd_shared(ptep))
 			flags |= PM_MMAP_EXCLUSIVE;
 
 		if (huge_pte_uffd_wp(pte))
-- 
2.44.0