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 9e7211122e27..be8449d48a8e 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;
         }