mm/damon/core: avoid holes in newly set monitoring target ranges

When there are two or more non-contiguous regions intersecting with given
new ranges, 'damon_set_regions()' does not fill the holes.  This commit
makes the function to fill the holes with newly created regions.

[sj@kernel.org: handle error from 'damon_fill_regions_holes()']
Link: https://lkml.kernel.org/r/20220913215420.57761-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20220909202901.57977-3-sj@kernel.org
Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Yun Levi <ppbuk5246@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/core.c b/mm/damon/core.c
index bae41990f4227ee8c87472c579a2b6cd7134ba54..5ad31d2feae404f02b87cfeb8585e53adfe6f540 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -168,6 +168,30 @@ static bool damon_intersect(struct damon_region *r,
        return !(r->ar.end <= re->start || re->end <= r->ar.start);
 }
 
+/*
+ * Fill holes in regions with new regions.
+ */
+static int damon_fill_regions_holes(struct damon_region *first,
+               struct damon_region *last, struct damon_target *t)
+{
+       struct damon_region *r = first;
+
+       damon_for_each_region_from(r, t) {
+               struct damon_region *next, *newr;
+
+               if (r == last)
+                       break;
+               next = damon_next_region(r);
+               if (r->ar.end != next->ar.start) {
+                       newr = damon_new_region(r->ar.end, next->ar.start);
+                       if (!newr)
+                               return -ENOMEM;
+                       damon_insert_region(newr, r, next, t);
+               }
+       }
+       return 0;
+}
+
 /*
  * damon_set_regions() - Set regions of a target for given address ranges.
  * @t:         the given target.
@@ -184,6 +208,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 {
        struct damon_region *r, *next;
        unsigned int i;
+       int err;
 
        /* Remove regions which are not in the new ranges */
        damon_for_each_region_safe(r, next, t) {
@@ -226,6 +251,11 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
                        first->ar.start = ALIGN_DOWN(range->start,
                                        DAMON_MIN_REGION);
                        last->ar.end = ALIGN(range->end, DAMON_MIN_REGION);
+
+                       /* fill possible holes in the range */
+                       err = damon_fill_regions_holes(first, last, t);
+                       if (err)
+                               return err;
                }
        }
        return 0;