ipc: scale msgmni to the number of ipc namespaces

Since all the namespaces see the same amount of memory (the total one) this
patch introduces a new variable that counts the ipc namespaces and divides
msg_ctlmni by this counter.

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 9e72111..be8449d 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -81,24 +81,28 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
 /*
  * Scale msgmni with the available lowmem size: the memory dedicated to msg
  * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
- * This should be done staying within the (MSGMNI , IPCMNI) range.
+ * Also take into account the number of nsproxies created so far.
+ * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
  */
 static void recompute_msgmni(struct ipc_namespace *ns)
 {
 	struct sysinfo i;
 	unsigned long allowed;
+	int nb_ns;
 
 	si_meminfo(&i);
 	allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
 		/ MSGMNB;
+	nb_ns = atomic_read(&nr_ipc_ns);
+	allowed /= nb_ns;
 
 	if (allowed < MSGMNI) {
 		ns->msg_ctlmni = MSGMNI;
 		goto out_callback;
 	}
 
-	if (allowed > IPCMNI) {
-		ns->msg_ctlmni = IPCMNI;
+	if (allowed > IPCMNI / nb_ns) {
+		ns->msg_ctlmni = IPCMNI / nb_ns;
 		goto out_callback;
 	}