[PATCH] mm: compaction: fix echo 1 > compact_memory return error issue

[Jason Liu]

when run the folloing command under shell, it will return error
sh/$ echo 1 > /proc/sys/vm/compact_memory
sh/$ sh: write error: Bad address

After strace, I found the following log:
...
write(1, "1\n", 2)               = 3
write(1, "", 4294967295)         = -1 EFAULT (Bad address)
write(2, "echo: write error: Bad address\n", 31echo: write error: Bad address
) = 31

This tells system return 3(COMPACT_COMPLETE) after write data to compact_memory.

The fix is to make the system just return 0 instead 3(COMPACT_COMPLETE) from
sysctl_compaction_handler after compaction_nodes finished.

Suggested-by:David Rientjes <rientjes@xxxxxxxxxx>
Cc:Mel Gorman <mgorman@xxxxxxx>
Cc:Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc:Rik van Riel <riel@xxxxxxxxxx>
Cc:Minchan Kim <minchan@xxxxxxxxxx>
Cc:KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Jason Liu <r64343@xxxxxxxxxxxxx>
---
 mm/compaction.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 6b807e4..f8f5c11 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1210,7 +1210,7 @@ static int compact_node(int nid)
 }
 
 /* Compact all nodes in the system */
-static int compact_nodes(void)
+static void compact_nodes(void)
 {
 	int nid;
 
@@ -1219,8 +1219,6 @@ static int compact_nodes(void)
 
 	for_each_online_node(nid)
 		compact_node(nid);
-
-	return COMPACT_COMPLETE;
 }
 
 /* The written value is actually unused, all memory is compacted */
@@ -1231,7 +1229,7 @@ int sysctl_compaction_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *length, loff_t *ppos)
 {
 	if (write)
-		return compact_nodes();
+		compact_nodes();
 
 	return 0;
 }
-- 
1.7.5.4


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/