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-rw-r--r--include/linux/mm.h2
-rw-r--r--include/linux/mman.h4
-rw-r--r--kernel/sysctl.c2
-rw-r--r--mm/mm_init.c22
-rw-r--r--mm/util.c41
5 files changed, 64 insertions, 7 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2830f1c0fdc3..1c3470550395 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -206,6 +206,8 @@ int overcommit_ratio_handler(struct ctl_table *, int, void *, size_t *,
loff_t *);
int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *,
loff_t *);
+int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *,
+ loff_t *);
#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 4b08e9c9c538..6f34c33075f9 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -57,8 +57,12 @@ extern struct percpu_counter vm_committed_as;
#ifdef CONFIG_SMP
extern s32 vm_committed_as_batch;
+extern void mm_compute_batch(int overcommit_policy);
#else
#define vm_committed_as_batch 0
+static inline void mm_compute_batch(int overcommit_policy)
+{
+}
#endif
unsigned long vm_memory_committed(void);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 1b4d2dc270a5..f785de3caac0 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2671,7 +2671,7 @@ static struct ctl_table vm_table[] = {
.data = &sysctl_overcommit_memory,
.maxlen = sizeof(sysctl_overcommit_memory),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = overcommit_policy_handler,
.extra1 = SYSCTL_ZERO,
.extra2 = &two,
},
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 435e5f794b3b..b06a30fbedff 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -13,6 +13,7 @@
#include <linux/memory.h>
#include <linux/notifier.h>
#include <linux/sched.h>
+#include <linux/mman.h>
#include "internal.h"
#ifdef CONFIG_DEBUG_MEMORY_INIT
@@ -144,14 +145,23 @@ EXPORT_SYMBOL_GPL(mm_kobj);
#ifdef CONFIG_SMP
s32 vm_committed_as_batch = 32;
-static void __meminit mm_compute_batch(void)
+void mm_compute_batch(int overcommit_policy)
{
u64 memsized_batch;
s32 nr = num_present_cpus();
s32 batch = max_t(s32, nr*2, 32);
-
- /* batch size set to 0.4% of (total memory/#cpus), or max int32 */
- memsized_batch = min_t(u64, (totalram_pages()/nr)/256, 0x7fffffff);
+ unsigned long ram_pages = totalram_pages();
+
+ /*
+ * For policy OVERCOMMIT_NEVER, set batch size to 0.4% of
+ * (total memory/#cpus), and lift it to 25% for other policies
+ * to easy the possible lock contention for percpu_counter
+ * vm_committed_as, while the max limit is INT_MAX
+ */
+ if (overcommit_policy == OVERCOMMIT_NEVER)
+ memsized_batch = min_t(u64, ram_pages/nr/256, INT_MAX);
+ else
+ memsized_batch = min_t(u64, ram_pages/nr/4, INT_MAX);
vm_committed_as_batch = max_t(s32, memsized_batch, batch);
}
@@ -162,7 +172,7 @@ static int __meminit mm_compute_batch_notifier(struct notifier_block *self,
switch (action) {
case MEM_ONLINE:
case MEM_OFFLINE:
- mm_compute_batch();
+ mm_compute_batch(sysctl_overcommit_memory);
default:
break;
}
@@ -176,7 +186,7 @@ static struct notifier_block compute_batch_nb __meminitdata = {
static int __init mm_compute_batch_init(void)
{
- mm_compute_batch();
+ mm_compute_batch(sysctl_overcommit_memory);
register_hotmemory_notifier(&compute_batch_nb);
return 0;
diff --git a/mm/util.c b/mm/util.c
index 1c9d097d7e48..8d6280c05238 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -746,6 +746,47 @@ int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer,
return ret;
}
+static void sync_overcommit_as(struct work_struct *dummy)
+{
+ percpu_counter_sync(&vm_committed_as);
+}
+
+int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table t;
+ int new_policy;
+ int ret;
+
+ /*
+ * The deviation of sync_overcommit_as could be big with loose policy
+ * like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to
+ * strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply
+ * with the strict "NEVER", and to avoid possible race condtion (even
+ * though user usually won't too frequently do the switching to policy
+ * OVERCOMMIT_NEVER), the switch is done in the following order:
+ * 1. changing the batch
+ * 2. sync percpu count on each CPU
+ * 3. switch the policy
+ */
+ if (write) {
+ t = *table;
+ t.data = &new_policy;
+ ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+ if (ret)
+ return ret;
+
+ mm_compute_batch(new_policy);
+ if (new_policy == OVERCOMMIT_NEVER)
+ schedule_on_each_cpu(sync_overcommit_as);
+ sysctl_overcommit_memory = new_policy;
+ } else {
+ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+ }
+
+ return ret;
+}
+
int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer,
size_t *lenp, loff_t *ppos)
{