mm: trigger page reclaim in alloc_contig_range() to stabilise watermarks

alloc_contig_range() performs memory allocation so it also should keep
track on keeping the correct level of memory watermarks. This commit adds
a call to *_slowpath style reclaim to grab enough pages to make sure that
the final collection of contiguous pages from freelists will not starve
the system.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4615531dcf66..22348ae1005d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5079,6 +5079,11 @@ static void __setup_per_zone_wmarks(void)
 
                 zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) + (tmp >> 2);
                 zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1);
+
+                zone->watermark[WMARK_MIN] += cma_wmark_pages(zone);
+                zone->watermark[WMARK_LOW] += cma_wmark_pages(zone);
+                zone->watermark[WMARK_HIGH] += cma_wmark_pages(zone);
+
                 setup_zone_migrate_reserve(zone);
                 spin_unlock_irqrestore(&zone->lock, flags);
         }
@@ -5684,6 +5689,54 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
         return ret > 0 ? 0 : ret;
 }
 
+/*
+ * Update zone's cma pages counter used for watermark level calculation.
+ */
+static inline void __update_cma_watermarks(struct zone *zone, int count)
+{
+        unsigned long flags;
+        spin_lock_irqsave(&zone->lock, flags);
+        zone->min_cma_pages += count;
+        spin_unlock_irqrestore(&zone->lock, flags);
+        setup_per_zone_wmarks();
+}
+
+/*
+ * Trigger memory pressure bump to reclaim some pages in order to be able to
+ * allocate 'count' pages in single page units. Does similar work as
+ *__alloc_pages_slowpath() function.
+ */
+static int __reclaim_pages(struct zone *zone, gfp_t gfp_mask, int count)
+{
+        enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+        struct zonelist *zonelist = node_zonelist(0, gfp_mask);
+        int did_some_progress = 0;
+        int order = 1;
+
+        /*
+         * Increase level of watermarks to force kswapd do his job
+         * to stabilise at new watermark level.
+         */
+        __update_cma_watermarks(zone, count);
+
+        /* Obey watermarks as if the page was being allocated */
+        while (!zone_watermark_ok(zone, 0, low_wmark_pages(zone), 0, 0)) {
+                wake_all_kswapd(order, zonelist, high_zoneidx, zone_idx(zone));
+
+                did_some_progress = __perform_reclaim(gfp_mask, order, zonelist,
+                                                      NULL);
+                if (!did_some_progress) {
+                        /* Exhausted what can be done so it's blamo time */
+                        out_of_memory(zonelist, gfp_mask, order, NULL, false);
+                }
+        }
+
+        /* Restore original watermark levels. */
+        __update_cma_watermarks(zone, -count);
+
+        return count;
+}
+
 /**
  * alloc_contig_range() -- tries to allocate given range of pages
  * @start:      start PFN to allocate
@@ -5782,6 +5835,13 @@ int alloc_contig_range(unsigned long start, unsigned long end,
                 goto done;
         }
 
+        /*
+         * Reclaim enough pages to make sure that contiguous allocation
+         * will not starve the system.
+         */
+        __reclaim_pages(zone, GFP_HIGHUSER_MOVABLE, end-start);
+
+        /* Grab isolated pages from freelists. */
         outer_end = isolate_freepages_range(outer_start, end);
         if (!outer_end) {
                 ret = -EBUSY;