linux-kernel - [PATCH 10/45] fs/proc: Create smaps_pud_range to handle PUD-mapped hugetlb vmas

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Message-ID: <20240704043132.28501-11-osalvador@suse.de>
Date: Thu,  4 Jul 2024 06:30:57 +0200
From: Oscar Salvador <osalvador@...e.de>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Peter Xu <peterx@...hat.com>,
	Muchun Song <muchun.song@...ux.dev>,
	David Hildenbrand <david@...hat.com>,
	SeongJae Park <sj@...nel.org>,
	Miaohe Lin <linmiaohe@...wei.com>,
	Michal Hocko <mhocko@...e.com>,
	Matthew Wilcox <willy@...radead.org>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Oscar Salvador <osalvador@...e.de>
Subject: [PATCH 10/45] fs/proc: Create smaps_pud_range to handle PUD-mapped hugetlb vmas

Normal THP cannot be PUD-mapped (besides devmap), but hugetlb can, so create
smaps_pud_range in order to handle PUD-mapped hugetlb vmas.

Signed-off-by: Oscar Salvador <osalvador@...e.de>
---
 fs/proc/task_mmu.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 78d84d7e2353..3f3460ff03b0 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -912,6 +912,40 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
 }
 #endif
 
+#ifdef CONFIG_HUGETLB_PAGE
+static int smaps_pud_range(pud_t *pudp, unsigned long addr, unsigned long end,
+			   struct mm_walk *walk)
+{
+	spinlock_t *ptl;
+	struct folio *folio;
+	struct vm_area_struct *vma = walk->vma;
+	struct mem_size_stats *mss = walk->private;
+
+	ptl = pud_huge_lock(pudp, vma);
+	if (!ptl)
+		return 0;
+
+	if (pud_present(*pudp)) {
+		folio = vm_normal_folio_pud(vma, addr, *pudp);
+	} else if (is_swap_pud(*pudp)) {
+		/* PUD-hugetlbs can have swap entries */
+		swp_entry_t swpent = pud_to_swp_entry(*pudp);
+
+		if (is_pfn_swap_entry(swpent))
+			folio = pfn_swap_entry_folio(swpent);
+	}
+
+	if (folio)
+		/* Only for now hugetlb pages can end up here */
+		mss_hugetlb_update(mss, folio, vma, (pte_t *)pudp);
+
+	spin_unlock(ptl);
+	return 0;
+}
+#else
+#define smaps_pud_range NULL
+#endif
+
 static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 			   struct mm_walk *walk)
 {
@@ -1061,12 +1095,14 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
 #endif /* HUGETLB_PAGE */
 
 static const struct mm_walk_ops smaps_walk_ops = {
+	.pud_entry              = smaps_pud_range,
 	.pmd_entry		= smaps_pte_range,
 	.hugetlb_entry		= smaps_hugetlb_range,
 	.walk_lock		= PGWALK_RDLOCK,
 };
 
 static const struct mm_walk_ops smaps_shmem_walk_ops = {
+	.pud_entry              = smaps_pud_range,
 	.pmd_entry		= smaps_pte_range,
 	.hugetlb_entry		= smaps_hugetlb_range,
 	.pte_hole		= smaps_pte_hole,
-- 
2.26.2