[PATCH v2 2/3] fs/proc/task_mmu: hold PTL in pagemap_hugetlb_range and gather_hugetlb_stats

[Jinjiang Tu <tujinjiang@huawei.com>]

Hold PTL in pagemap_hugetlb_range() and gather_hugetlb_stats() to avoid
operating on stale page, as pagemap_pmd_range() and gather_pte_stats() have
done.

Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
 fs/proc/task_mmu.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 0102ab3aaec1..68077aef6c5b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1893,12 +1893,14 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 	struct pagemapread *pm = walk->private;
 	struct vm_area_struct *vma = walk->vma;
 	u64 flags = 0, frame = 0;
+	spinlock_t *ptl;
 	int err = 0;
 	pte_t pte;
 
 	if (vma->vm_flags & VM_SOFTDIRTY)
 		flags |= PM_SOFT_DIRTY;
 
+	ptl = huge_pte_lock(hstate_vma(vma), walk->mm, ptep);
 	pte = huge_ptep_get(walk->mm, addr, ptep);
 	if (pte_present(pte)) {
 		struct folio *folio = page_folio(pte_page(pte));
@@ -1926,11 +1928,12 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 
 		err = add_to_pagemap(&pme, pm);
 		if (err)
-			return err;
+			break;
 		if (pm->show_pfn && (flags & PM_PRESENT))
 			frame++;
 	}
 
+	spin_unlock(ptl);
 	cond_resched();
 
 	return err;
@@ -3004,17 +3007,22 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
 static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 		unsigned long addr, unsigned long end, struct mm_walk *walk)
 {
-	pte_t huge_pte = huge_ptep_get(walk->mm, addr, pte);
+	pte_t huge_pte;
 	struct numa_maps *md;
 	struct page *page;
+	spinlock_t *ptl;
 
+	ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
+	huge_pte = huge_ptep_get(walk->mm, addr, pte);
 	if (!pte_present(huge_pte))
-		return 0;
+		goto out;
 
 	page = pte_page(huge_pte);
 
 	md = walk->private;
 	gather_stats(page, md, pte_dirty(huge_pte), 1);
+out:
+	spin_unlock(ptl);
 	return 0;
 }
 
-- 
2.43.0