damon: Convert __damon_va_three_regions to use the VMA iterator

This rather specialised walk can use the VMA iterator.  If this proves
to be too slow, we can write a custom routine to find the two largest
gaps, but it will be somewhat complicated, so let's see if we need it
first.

Update the kunit test case to use the maple tree.  This also fixes an
issue with the kunit testcase not adding the last VMA to the list.

Fixes: 17ccae8bb5c9 (mm/damon: add kunit tests)
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/mm/damon/vaddr-test.h b/mm/damon/vaddr-test.h
index 6a1b9272ea123a1f2991ad632daf17ef0b173c76..ed94dbffd82fb06ebe04a417419294357b233542 100644 (file)
--- a/mm/damon/vaddr-test.h
+++ b/mm/damon/vaddr-test.h
@@ -13,34 +13,21 @@
 #define _DAMON_VADDR_TEST_H
 
 #include <kunit/test.h>
+#include "../../mm/internal.h"
 
-static void __link_vmas(struct vm_area_struct *vmas, ssize_t nr_vmas)
+static void __link_vmas(struct maple_tree *mt, struct vm_area_struct *vmas,
+                       ssize_t nr_vmas)
 {
-       int i, j;
-       unsigned long largest_gap, gap;
+       int i;
+       MA_STATE(mas, mt, 0, 0);
 
        if (!nr_vmas)
                return;
 
-       for (i = 0; i < nr_vmas - 1; i++) {
-               vmas[i].vm_next = &vmas[i + 1];
-
-               vmas[i].vm_rb.rb_left = NULL;
-               vmas[i].vm_rb.rb_right = &vmas[i + 1].vm_rb;
-
-               largest_gap = 0;
-               for (j = i; j < nr_vmas; j++) {
-                       if (j == 0)
-                               continue;
-                       gap = vmas[j].vm_start - vmas[j - 1].vm_end;
-                       if (gap > largest_gap)
-                               largest_gap = gap;
-               }
-               vmas[i].rb_subtree_gap = largest_gap;
-       }
-       vmas[i].vm_next = NULL;
-       vmas[i].vm_rb.rb_right = NULL;
-       vmas[i].rb_subtree_gap = 0;
+       mas_lock(&mas);
+       for (i = 0; i < nr_vmas; i++)
+               vma_mas_store(&vmas[i], &mas);
+       mas_unlock(&mas);
 }
 
 /*
@@ -72,6 +59,7 @@ static void __link_vmas(struct vm_area_struct *vmas, ssize_t nr_vmas)
  */
 static void damon_test_three_regions_in_vmas(struct kunit *test)
 {
+       static struct mm_struct mm;
        struct damon_addr_range regions[3] = {0,};
        /* 10-20-25, 200-210-220, 300-305, 307-330 */
        struct vm_area_struct vmas[] = {
@@ -83,9 +71,10 @@ static void damon_test_three_regions_in_vmas(struct kunit *test)
                (struct vm_area_struct) {.vm_start = 307, .vm_end = 330},
        };
 
-       __link_vmas(vmas, 6);
+       mt_init_flags(&mm.mm_mt, MM_MT_FLAGS);
+       __link_vmas(&mm.mm_mt, vmas, ARRAY_SIZE(vmas));
 
-       __damon_va_three_regions(&vmas[0], regions);
+       __damon_va_three_regions(&mm, regions);
 
        KUNIT_EXPECT_EQ(test, 10ul, regions[0].start);
        KUNIT_EXPECT_EQ(test, 25ul, regions[0].end);

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 89b6468da2b9b0d595a34bbcf4ded9231f80c2ad..7f06422d542cd97c35cebdd747cff31873371667 100644 (file)
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -113,37 +113,38 @@ static unsigned long sz_range(struct damon_addr_range *r)
  *
  * Returns 0 if success, or negative error code otherwise.
  */
-static int __damon_va_three_regions(struct vm_area_struct *vma,
+static int __damon_va_three_regions(struct mm_struct *mm,
                                       struct damon_addr_range regions[3])
 {
-       struct damon_addr_range gap = {0}, first_gap = {0}, second_gap = {0};
-       struct vm_area_struct *last_vma = NULL;
-       unsigned long start = 0;
-       struct rb_root rbroot;
-
-       /* Find two biggest gaps so that first_gap > second_gap > others */
-       for (; vma; vma = vma->vm_next) {
-               if (!last_vma) {
-                       start = vma->vm_start;
-                       goto next;
-               }
+       struct damon_addr_range first_gap = {0}, second_gap = {0};
+       VMA_ITERATOR(vmi, mm, 0);
+       struct vm_area_struct *vma, *prev = NULL;
+       unsigned long start;
 
-               if (vma->rb_subtree_gap <= sz_range(&second_gap)) {
-                       rbroot.rb_node = &vma->vm_rb;
-                       vma = rb_entry(rb_last(&rbroot),
-                                       struct vm_area_struct, vm_rb);
+       /*
+        * Find the two biggest gaps so that first_gap > second_gap > others.
+        * If this is too slow, it can be optimised to examine the maple
+        * tree gaps.
+        */
+       for_each_vma(vmi, vma) {
+               unsigned long gap;
+
+               if (!prev) {
+                       start = vma->vm_start;
                        goto next;
                }
-
-               gap.start = last_vma->vm_end;
-               gap.end = vma->vm_start;
-               if (sz_range(&gap) > sz_range(&second_gap)) {
-                       swap(gap, second_gap);
-                       if (sz_range(&second_gap) > sz_range(&first_gap))
-                               swap(second_gap, first_gap);
+               gap = vma->vm_start - prev->vm_end;
+
+               if (gap > sz_range(&first_gap)) {
+                       second_gap = first_gap;
+                       first_gap.start = prev->vm_end;
+                       first_gap.end = vma->vm_start;
+               } else if (gap > sz_range(&second_gap)) {
+                       second_gap.start = prev->vm_end;
+                       second_gap.end = vma->vm_start;
                }
 next:
-               last_vma = vma;
+               prev = vma;
        }
 
        if (!sz_range(&second_gap) || !sz_range(&first_gap))
@@ -159,7 +160,7 @@ next:
        regions[1].start = ALIGN(first_gap.end, DAMON_MIN_REGION);
        regions[1].end = ALIGN(second_gap.start, DAMON_MIN_REGION);
        regions[2].start = ALIGN(second_gap.end, DAMON_MIN_REGION);
-       regions[2].end = ALIGN(last_vma->vm_end, DAMON_MIN_REGION);
+       regions[2].end = ALIGN(prev->vm_end, DAMON_MIN_REGION);
 
        return 0;
 }
@@ -180,7 +181,7 @@ static int damon_va_three_regions(struct damon_target *t,
                return -EINVAL;
 
        mmap_read_lock(mm);
-       rc = __damon_va_three_regions(mm->mmap, regions);
+       rc = __damon_va_three_regions(mm, regions);
        mmap_read_unlock(mm);
 
        mmput(mm);