mqueue: don't use kmalloc with KMALLOC_MAX_SIZE

KMALLOC_MAX_SIZE is not a good threshold.  It is extremely high and
problematic.  Unfortunately, some silly drivers depend on this and we
can't change it.  But any new code needn't use such extreme ugly high
order allocations.  It brings us awful fragmentation issues and system
slowdown.

Signed-off-by: KOSAKI Motohiro <[email protected]>
Acked-by: Doug Ledford <[email protected]>
Acked-by: Joe Korty <[email protected]>
Cc: Amerigo Wang <[email protected]>
Cc: Serge E. Hallyn <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Joe Korty <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

ipc/mqueue.c

@@ -153,7 +153,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 			info->attr.mq_msgsize = attr->mq_msgsize;
 		}
 		mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
-		if (mq_msg_tblsz > KMALLOC_MAX_SIZE)
+		if (mq_msg_tblsz > PAGE_SIZE)
 			info->messages = vmalloc(mq_msg_tblsz);
 		else
 			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
@@ -266,7 +266,7 @@ static void mqueue_evict_inode(struct inode *inode)
 	spin_lock(&info->lock);
 	for (i = 0; i < info->attr.mq_curmsgs; i++)
 		free_msg(info->messages[i]);
-	if (info->attr.mq_maxmsg * sizeof(struct msg_msg *) > KMALLOC_MAX_SIZE)
+	if (is_vmalloc_addr(info->messages))
 		vfree(info->messages);
 	else
 		kfree(info->messages);