mm: use walk_page_range() instead of custom page table walking code

Converting show_numa_map() to use the generic routine decouples the
function from mempolicy.c, allowing it to be moved out of the mm subsystem
and into fs/proc.

Also, include KSM pages in /proc/pid/numa_maps statistics.  The pagewalk
logic implemented by check_pte_range() failed to account for such pages as
they were not applicable to the page migration case.

Signed-off-by: Stephen Wilson <wilsons@start.ca>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 68 insertions, 7 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5bfb03ef3cb..945e85de2d4 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2531,6 +2531,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
 }
 
 struct numa_maps {
+        struct vm_area_struct *vma;
         unsigned long pages;
         unsigned long anon;
         unsigned long active;
@@ -2568,6 +2569,41 @@ static void gather_stats(struct page *page, void *private, int pte_dirty)
         md->node[page_to_nid(page)]++;
 }
 
+static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
+                unsigned long end, struct mm_walk *walk)
+{
+        struct numa_maps *md;
+        spinlock_t *ptl;
+        pte_t *orig_pte;
+        pte_t *pte;
+
+        md = walk->private;
+        orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+        do {
+                struct page *page;
+                int nid;
+
+                if (!pte_present(*pte))
+                        continue;
+
+                page = vm_normal_page(md->vma, addr, *pte);
+                if (!page)
+                        continue;
+
+                if (PageReserved(page))
+                        continue;
+
+                nid = page_to_nid(page);
+                if (!node_isset(nid, node_states[N_HIGH_MEMORY]))
+                        continue;
+
+                gather_stats(page, md, pte_dirty(*pte));
+
+        } while (pte++, addr += PAGE_SIZE, addr != end);
+        pte_unmap_unlock(orig_pte, ptl);
+        return 0;
+}
+
 #ifdef CONFIG_HUGETLB_PAGE
 static void check_huge_range(struct vm_area_struct *vma,
                 unsigned long start, unsigned long end,
@@ -2597,12 +2633,35 @@ static void check_huge_range(struct vm_area_struct *vma,
                 gather_stats(page, md, pte_dirty(*ptep));
         }
 }
+
+static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
+                unsigned long addr, unsigned long end, struct mm_walk *walk)
+{
+        struct page *page;
+
+        if (pte_none(*pte))
+                return 0;
+
+        page = pte_page(*pte);
+        if (!page)
+                return 0;
+
+        gather_stats(page, walk->private, pte_dirty(*pte));
+        return 0;
+}
+
 #else
 static inline void check_huge_range(struct vm_area_struct *vma,
                 unsigned long start, unsigned long end,
                 struct numa_maps *md)
 {
 }
+
+static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
+                unsigned long addr, unsigned long end, struct mm_walk *walk)
+{
+        return 0;
+}
 #endif
 
 /*
@@ -2615,6 +2674,7 @@ int show_numa_map(struct seq_file *m, void *v)
         struct numa_maps *md;
         struct file *file = vma->vm_file;
         struct mm_struct *mm = vma->vm_mm;
+        struct mm_walk walk = {};
         struct mempolicy *pol;
         int n;
         char buffer[50];
@@ -2626,6 +2686,13 @@ int show_numa_map(struct seq_file *m, void *v)
         if (!md)
                 return 0;
 
+        md->vma = vma;
+
+        walk.hugetlb_entry = gather_hugetbl_stats;
+        walk.pmd_entry = gather_pte_stats;
+        walk.private = md;
+        walk.mm = mm;
+
         pol = get_vma_policy(priv->task, vma, vma->vm_start);
         mpol_to_str(buffer, sizeof(buffer), pol, 0);
         mpol_cond_put(pol);
@@ -2642,13 +2709,7 @@ int show_numa_map(struct seq_file *m, void *v)
                 seq_printf(m, " stack");
         }
 
-        if (is_vm_hugetlb_page(vma)) {
-                check_huge_range(vma, vma->vm_start, vma->vm_end, md);
-                seq_printf(m, " huge");
-        } else {
-                check_pgd_range(vma, vma->vm_start, vma->vm_end,
-                        &node_states[N_HIGH_MEMORY], MPOL_MF_STATS, md);
-        }
+        walk_page_range(vma->vm_start, vma->vm_end, &walk);
 
         if (!md->pages)
                 goto out;