Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android

[firefly-linux-kernel-4.4.55.git] / mm / page_alloc.c

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b0ca09f607b4c6bb6db5c4c54c8b28e455599121..cc99ff2d85c5bca1b12b11f128a66c9ce10f5373 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -231,9 +231,21 @@ compound_page_dtor * const compound_page_dtors[] = {
 #endif
 };
 
+/*
+ * Try to keep at least this much lowmem free.  Do not allow normal
+ * allocations below this point, only high priority ones. Automatically
+ * tuned according to the amount of memory in the system.
+ */
 int min_free_kbytes = 1024;
 int user_min_free_kbytes = -1;
 
+/*
+ * Extra memory for the system to try freeing. Used to temporarily
+ * free memory, to make space for new workloads. Anyone can allocate
+ * down to the min watermarks controlled by min_free_kbytes above.
+ */
+int extra_free_kbytes = 0;
+
 static unsigned long __meminitdata nr_kernel_pages;
 static unsigned long __meminitdata nr_all_pages;
 static unsigned long __meminitdata dma_reserve;
@@ -6022,6 +6034,7 @@ static void setup_per_zone_lowmem_reserve(void)
 static void __setup_per_zone_wmarks(void)
 {
        unsigned long pages_min = min_free_kbytes >> (PAGE_SHIFT - 10);
+       unsigned long pages_low = extra_free_kbytes >> (PAGE_SHIFT - 10);
        unsigned long lowmem_pages = 0;
        struct zone *zone;
        unsigned long flags;
@@ -6033,11 +6046,14 @@ static void __setup_per_zone_wmarks(void)
        }
 
        for_each_zone(zone) {
-               u64 tmp;
+               u64 min, low;
 
                spin_lock_irqsave(&zone->lock, flags);
-               tmp = (u64)pages_min * zone->managed_pages;
-               do_div(tmp, lowmem_pages);
+               min = (u64)pages_min * zone->managed_pages;
+               do_div(min, lowmem_pages);
+               low = (u64)pages_low * zone->managed_pages;
+               do_div(low, vm_total_pages);
+
                if (is_highmem(zone)) {
                        /*
                         * __GFP_HIGH and PF_MEMALLOC allocations usually don't
@@ -6058,11 +6074,13 @@ static void __setup_per_zone_wmarks(void)
                         * If it's a lowmem zone, reserve a number of pages
                         * proportionate to the zone's size.
                         */
-                       zone->watermark[WMARK_MIN] = tmp;
+                       zone->watermark[WMARK_MIN] = min;
                }
 
-               zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) + (tmp >> 2);
-               zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) + (tmp >> 1);
+               zone->watermark[WMARK_LOW]  = min_wmark_pages(zone) +
+                                       low + (min >> 2);
+               zone->watermark[WMARK_HIGH] = min_wmark_pages(zone) +
+                                       low + (min >> 1);
 
                __mod_zone_page_state(zone, NR_ALLOC_BATCH,
                        high_wmark_pages(zone) - low_wmark_pages(zone) -
@@ -6185,7 +6203,7 @@ core_initcall(init_per_zone_wmark_min)
 /*
  * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
  *     that we can call two helper functions whenever min_free_kbytes
- *     changes.
+ *     or extra_free_kbytes changes.
  */
 int min_free_kbytes_sysctl_handler(struct ctl_table *table, int write,
        void __user *buffer, size_t *length, loff_t *ppos)