[RFC PATCH 6/7] mm: Make /proc/pid/numa_maps use the new generic pagewalk API

[Oscar Salvador]

Have /proc/pid/numa_maps make use of the new generic API, and remove
the code which was using the old one

Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
---
 fs/proc/task_mmu.c | 136 +++++++++++----------------------------------
 1 file changed, 32 insertions(+), 104 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index afbcdb11ad80..776e7a6baf00 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -3048,108 +3048,6 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
 	return page;
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static struct page *can_gather_numa_stats_pmd(pmd_t pmd,
-					      struct vm_area_struct *vma,
-					      unsigned long addr)
-{
-	struct page *page;
-	int nid;
-
-	if (!pmd_present(pmd))
-		return NULL;
-
-	page = vm_normal_page_pmd(vma, addr, pmd);
-	if (!page)
-		return NULL;
-
-	if (PageReserved(page))
-		return NULL;
-
-	nid = page_to_nid(page);
-	if (!node_isset(nid, node_states[N_MEMORY]))
-		return NULL;
-
-	return page;
-}
-#endif
-
-static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
-		unsigned long end, struct mm_walk *walk)
-{
-	struct numa_maps *md = walk->private;
-	struct vm_area_struct *vma = walk->vma;
-	spinlock_t *ptl;
-	pte_t *orig_pte;
-	pte_t *pte;
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	ptl = pmd_trans_huge_lock(pmd, vma);
-	if (ptl) {
-		struct page *page;
-
-		page = can_gather_numa_stats_pmd(*pmd, vma, addr);
-		if (page)
-			gather_stats(page, md, pmd_dirty(*pmd),
-				     HPAGE_PMD_SIZE/PAGE_SIZE);
-		spin_unlock(ptl);
-		return 0;
-	}
-#endif
-	orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
-	if (!pte) {
-		walk->action = ACTION_AGAIN;
-		return 0;
-	}
-	do {
-		pte_t ptent = ptep_get(pte);
-		struct page *page = can_gather_numa_stats(ptent, vma, addr);
-		if (!page)
-			continue;
-		gather_stats(page, md, pte_dirty(ptent), 1);
-
-	} while (pte++, addr += PAGE_SIZE, addr != end);
-	pte_unmap_unlock(orig_pte, ptl);
-	cond_resched();
-	return 0;
-}
-#ifdef CONFIG_HUGETLB_PAGE
-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;
-	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))
-		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;
-}
-
-#else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
-{
-	return 0;
-}
-#endif
-
-static const struct mm_walk_ops show_numa_ops = {
-	.hugetlb_entry = gather_hugetlb_stats,
-	.pmd_entry = gather_pte_stats,
-	.walk_lock = PGWALK_RDLOCK,
-};
-
 /*
  * Display pages allocated per node and memory policy via /proc.
  */
@@ -3161,9 +3059,15 @@ static int show_numa_map(struct seq_file *m, void *v)
 	struct numa_maps *md = &numa_priv->md;
 	struct file *file = vma->vm_file;
 	struct mm_struct *mm = vma->vm_mm;
+	struct pt_range_walk ptw = {
+		.mm = mm
+	};
+	enum pt_range_walk_type type;
+	pt_type_flags_t flags;
 	char buffer[64];
 	struct mempolicy *pol;
 	pgoff_t ilx;
+	int nr_pages;
 	int nid;
 
 	if (!mm)
@@ -3194,8 +3098,32 @@ static int show_numa_map(struct seq_file *m, void *v)
 	if (is_vm_hugetlb_page(vma))
 		seq_puts(m, " huge");
 
-	/* mmap_lock is held by m_start */
-	walk_page_vma(vma, &show_numa_ops, md);
+	flags = PT_TYPE_FOLIO;
+	type = pt_range_walk_start(&ptw, vma, vma->vm_start, vma->vm_end, flags);
+	while (type != PTW_DONE) {
+
+		if (!ptw.folio || !ptw.page || PageReserved(ptw.page))
+			goto not_found;
+
+		nid = page_to_nid(ptw.page);
+		if (!node_isset(nid, node_states[N_MEMORY]))
+			goto not_found;
+
+		if (is_vm_hugetlb_page(vma))
+			/*
+			 * As opposed to THP, HugeTLB counts the entire huge
+			 * page as one unit size.
+			 */
+			nr_pages = ptw.nr_entries;
+		else
+			nr_pages = ptw.size / PAGE_SIZE;
+
+		gather_stats(ptw.page, md, ptw.dirty, nr_pages);
+not_found:
+		type = pt_range_walk_next(&ptw, vma, vma->vm_start, vma->vm_end, flags);
+
+	}
+	pt_range_walk_done(&ptw);
 
 	if (!md->pages)
 		goto out;
-- 
2.35.3