3 files changed, 36 insertions, 2 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 834b2d785f1e..39552de6e1db 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -86,6 +86,7 @@ EXPORT_SYMBOL(vm_get_page_prot);
 
 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
+unsigned long sysctl_overcommit_kbytes __read_mostly;
 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
diff --git a/mm/nommu.c b/mm/nommu.c
index fec093adad9c..8740213b1647 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -60,6 +60,7 @@ unsigned long highest_memmap_pfn;
 struct percpu_counter vm_committed_as;
 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
 int sysctl_overcommit_ratio = 50; /* default is 50% */
+unsigned long sysctl_overcommit_kbytes __read_mostly;
 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
diff --git a/mm/util.c b/mm/util.c
index 808f375648e7..a24aa22f2473 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -404,13 +404,45 @@ struct address_space *page_mapping(struct page *page)
         return mapping;
 }
 
+int overcommit_ratio_handler(struct ctl_table *table, int write,
+                             void __user *buffer, size_t *lenp,
+                             loff_t *ppos)
+{
+        int ret;
+
+        ret = proc_dointvec(table, write, buffer, lenp, ppos);
+        if (ret == 0 && write)
+                sysctl_overcommit_kbytes = 0;
+        return ret;
+}
+
+int overcommit_kbytes_handler(struct ctl_table *table, int write,
+                             void __user *buffer, size_t *lenp,
+                             loff_t *ppos)
+{
+        int ret;
+
+        ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+        if (ret == 0 && write)
+                sysctl_overcommit_ratio = 0;
+        return ret;
+}
+
 /*
  * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
  */
 unsigned long vm_commit_limit(void)
 {
-        return ((totalram_pages - hugetlb_total_pages())
-                * sysctl_overcommit_ratio / 100) + total_swap_pages;
+        unsigned long allowed;
+
+        if (sysctl_overcommit_kbytes)
+                allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
+        else
+                allowed = ((totalram_pages - hugetlb_total_pages())
+                           * sysctl_overcommit_ratio / 100);
+        allowed += total_swap_pages;
+
+        return allowed;
 }