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-rw-r--r--include/linux/mmzone.h6
-rw-r--r--include/linux/swap.h1
-rw-r--r--mm/page-writeback.c5
-rw-r--r--mm/page_alloc.c19
4 files changed, 29 insertions, 2 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3ac040f19369..ca6ca92418a6 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -317,6 +317,12 @@ struct zone {
*/
unsigned long lowmem_reserve[MAX_NR_ZONES];
+ /*
+ * This is a per-zone reserve of pages that should not be
+ * considered dirtyable memory.
+ */
+ unsigned long dirty_balance_reserve;
+
#ifdef CONFIG_NUMA
int node;
/*
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1e22e126d2ac..06061a7f8e69 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -207,6 +207,7 @@ struct swap_list_t {
/* linux/mm/page_alloc.c */
extern unsigned long totalram_pages;
extern unsigned long totalreserve_pages;
+extern unsigned long dirty_balance_reserve;
extern unsigned int nr_free_buffer_pages(void);
extern unsigned int nr_free_pagecache_pages(void);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index c081bf62202b..9ab6de82d8e6 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -157,7 +157,7 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
&NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
x += zone_page_state(z, NR_FREE_PAGES) +
- zone_reclaimable_pages(z);
+ zone_reclaimable_pages(z) - z->dirty_balance_reserve;
}
/*
* Make sure that the number of highmem pages is never larger
@@ -181,7 +181,8 @@ static unsigned long determine_dirtyable_memory(void)
{
unsigned long x;
- x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
+ x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages() -
+ dirty_balance_reserve;
if (!vm_highmem_is_dirtyable)
x -= highmem_dirtyable_memory(x);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 93baebcc06f3..2cb9eb71e282 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -97,6 +97,14 @@ EXPORT_SYMBOL(node_states);
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
+/*
+ * When calculating the number of globally allowed dirty pages, there
+ * is a certain number of per-zone reserves that should not be
+ * considered dirtyable memory. This is the sum of those reserves
+ * over all existing zones that contribute dirtyable memory.
+ */
+unsigned long dirty_balance_reserve __read_mostly;
+
int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
@@ -4822,8 +4830,19 @@ static void calculate_totalreserve_pages(void)
if (max > zone->present_pages)
max = zone->present_pages;
reserve_pages += max;
+ /*
+ * Lowmem reserves are not available to
+ * GFP_HIGHUSER page cache allocations and
+ * kswapd tries to balance zones to their high
+ * watermark. As a result, neither should be
+ * regarded as dirtyable memory, to prevent a
+ * situation where reclaim has to clean pages
+ * in order to balance the zones.
+ */
+ zone->dirty_balance_reserve = max;
}
}
+ dirty_balance_reserve = reserve_pages;
totalreserve_pages = reserve_pages;
}