+/*
+ * 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);
+ }
+ }
+
+ /* Restore original watermark levels. */
+ __update_cma_watermarks(zone, -count);
+
+ return count;
+}
+