[PATCH -mm] fixes & cleanups for "add extra free kbytes tunable"

[Rik van Riel <riel@redhat.com>]

All the fixes suggested by Andrew Morton.   Not much of a changelog
since the patch should probably be folded into
mm-add-extra-free-kbytes-tunable.patch

Thank you for pointing these out, Andrew.

Signed-off-by: Rik van Riel <riel@redhat.com>
---
 include/linux/mmzone.h |    2 +-
 include/linux/swap.h   |    2 ++
 kernel/sysctl.c        |    6 ++----
 mm/page_alloc.c        |   13 +++++++------
 4 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index be1ac8d..7013bab 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -772,7 +772,7 @@ static inline int is_dma(struct zone *zone)
 
 /* These two functions are used to setup the per zone pages min values */
 struct ctl_table;
-int min_free_kbytes_sysctl_handler(struct ctl_table *, int,
+int free_kbytes_sysctl_handler(struct ctl_table *, int,
 					void __user *, size_t *, loff_t *);
 extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int,
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 14d6249..0679ed5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -207,6 +207,8 @@ struct swap_list_t {
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
 extern unsigned long totalreserve_pages;
+extern int min_free_kbytes;
+extern int extra_free_kbytes;
 extern unsigned int nr_free_buffer_pages(void);
 extern unsigned int nr_free_pagecache_pages(void);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 01a9acd..a3a015c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -95,8 +95,6 @@ extern int suid_dumpable;
 extern char core_pattern[];
 extern unsigned int core_pipe_limit;
 extern int pid_max;
-extern int min_free_kbytes;
-extern int extra_free_kbytes;
 extern int pid_max_min, pid_max_max;
 extern int sysctl_drop_caches;
 extern int percpu_pagelist_fraction;
@@ -1186,7 +1184,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &min_free_kbytes,
 		.maxlen		= sizeof(min_free_kbytes),
 		.mode		= 0644,
-		.proc_handler	= min_free_kbytes_sysctl_handler,
+		.proc_handler	= free_kbytes_sysctl_handler,
 		.extra1		= &zero,
 	},
 	{
@@ -1194,7 +1192,7 @@ static struct ctl_table vm_table[] = {
 		.data		= &extra_free_kbytes,
 		.maxlen		= sizeof(extra_free_kbytes),
 		.mode		= 0644,
-		.proc_handler	= min_free_kbytes_sysctl_handler,
+		.proc_handler	= free_kbytes_sysctl_handler,
 		.extra1		= &zero,
 	},
 	{
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 47d185c..14fc9e9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -183,11 +183,12 @@ static char * const zone_names[MAX_NR_ZONES] = {
 int min_free_kbytes = 1024;
 
 /*
- * 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.
+ * Extra memory for the system to try freeing between the min and
+ * low watermarks.  Useful for workloads that require low latency
+ * memory allocations in bursts larger than the normal gap between
+ * low and min.
  */
-int extra_free_kbytes = 0;
+int extra_free_kbytes;
 
 static unsigned long __meminitdata nr_kernel_pages;
 static unsigned long __meminitdata nr_all_pages;
@@ -5280,11 +5281,11 @@ int __meminit init_per_zone_wmark_min(void)
 module_init(init_per_zone_wmark_min)
 
 /*
- * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so 
+ * free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so 
  *	that we can call two helper functions whenever min_free_kbytes
  *	or extra_free_kbytes changes.
  */
-int min_free_kbytes_sysctl_handler(ctl_table *table, int write, 
+int free_kbytes_sysctl_handler(ctl_table *table, int write, 
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
 	proc_dointvec(table, write, buffer, length, ppos);