diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index ff234d229cbbc581ec53a41dcc7725565d0747d4..17256f2ad919aa99cd2271eb8b05d09d5c8e2b62 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -312,8 +312,6 @@ The lowmem_reserve_ratio is an array. You can see them by reading this file.
% cat /proc/sys/vm/lowmem_reserve_ratio
256 256 32
-
-Note: # of this elements is one fewer than number of zones. Because the highest
- zone's value is not necessary for following calculation.
But, these values are not used directly. The kernel calculates # of protection
pages for each zones from them. These are shown as array of protection pages
@@ -364,7 +362,8 @@ As above expression, they are reciprocal number of ratio.
pages of higher zones on the node.
If you would like to protect more pages, smaller values are effective.
-The minimum value is 1 (1/1 -> 100%).
+The minimum value is 1 (1/1 -> 100%). The value less than 1 completely
+disables protection of the pages.
==============================================================
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index a0c9e45a859a7ca364cbe43adafc27710455642c..32699b2dc52a1f8bece62d3ae7d35d67cbe1e88f 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -885,7 +885,7 @@ int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
int watermark_scale_factor_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
-extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
+extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES];
int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b046678483750ff8f235dfc1881417248977d645..34a4c12d267587911a48d7eac0f70fc9ee789447 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -205,17 +205,18 @@ static void __free_pages_ok(struct page *page, unsigned int order);
* TBD: should special case ZONE_DMA32 machines here - in those we normally
* don't need any ZONE_NORMAL reservation
*/
-int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = {
#ifdef CONFIG_ZONE_DMA
- 256,
+ [ZONE_DMA] = 256,
#endif
#ifdef CONFIG_ZONE_DMA32
- 256,
+ [ZONE_DMA32] = 256,
#endif
+ [ZONE_NORMAL] = 32,
#ifdef CONFIG_HIGHMEM
- 32,
+ [ZONE_HIGHMEM] = 0,
#endif
- 32,
+ [ZONE_MOVABLE] = 0,
};
EXPORT_SYMBOL(totalram_pages);
@@ -7132,13 +7133,15 @@ static void setup_per_zone_lowmem_reserve(void)
struct zone *lower_zone;
idx--;
-
- if (sysctl_lowmem_reserve_ratio[idx] < 1)
- sysctl_lowmem_reserve_ratio[idx] = 1;
-
lower_zone = pgdat->node_zones + idx;
- lower_zone->lowmem_reserve[j] = managed_pages /
- sysctl_lowmem_reserve_ratio[idx];
+
+ if (sysctl_lowmem_reserve_ratio[idx] < 1) {
+ sysctl_lowmem_reserve_ratio[idx] = 0;
+ lower_zone->lowmem_reserve[j] = 0;
+ } else {
+ lower_zone->lowmem_reserve[j] =
+ managed_pages / sysctl_lowmem_reserve_ratio[idx];
+ }
managed_pages += lower_zone->managed_pages;
}
}