mlx4_core: Allow large mlx4_buddy bitmaps

mlx4_buddy_init uses kmalloc() to allocate bitmaps, which fails when
the required size is beyond the max supported value (or when memory is
too fragmented to handle a huge allocation).  Extend this to use use
vmalloc() if kmalloc() fails, and take that into account when freeing
the bitmaps as well.

This fixes a driver load failure when log num mtt is 26 or higher, and
is a step in the direction of allowing to register huge amounts of
memory on large memory systems.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/net/ethernet/mellanox/mlx4/mr.c

@@ -37,6 +37,7 @@
 #include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/kernel.h>
+#include <linux/vmalloc.h>
 
 #include <linux/mlx4/cmd.h>
 
@@ -130,8 +131,11 @@ static int mlx4_buddy_init(struct mlx4_buddy *buddy, int max_order)
 	for (i = 0; i <= buddy->max_order; ++i) {
 		s = BITS_TO_LONGS(1 << (buddy->max_order - i));
 		buddy->bits[i] = kmalloc(s * sizeof (long), GFP_KERNEL);
-		if (!buddy->bits[i])
-			goto err_out_free;
+		if (!buddy->bits[i]) {
+			buddy->bits[i] = vmalloc(s * sizeof(long));
+			if (!buddy->bits[i])
+				goto err_out_free;
+		}
 		bitmap_zero(buddy->bits[i], 1 << (buddy->max_order - i));
 	}
 
@@ -142,7 +146,10 @@ static int mlx4_buddy_init(struct mlx4_buddy *buddy, int max_order)
 
 err_out_free:
 	for (i = 0; i <= buddy->max_order; ++i)
-		kfree(buddy->bits[i]);
+		if (buddy->bits[i] && is_vmalloc_addr(buddy->bits[i]))
+			vfree(buddy->bits[i]);
+		else
+			kfree(buddy->bits[i]);
 
 err_out:
 	kfree(buddy->bits);
@@ -156,7 +163,10 @@ static void mlx4_buddy_cleanup(struct mlx4_buddy *buddy)
 	int i;
 
 	for (i = 0; i <= buddy->max_order; ++i)
-		kfree(buddy->bits[i]);
+		if (is_vmalloc_addr(buddy->bits[i]))
+			vfree(buddy->bits[i]);
+		else
+			kfree(buddy->bits[i]);
 
 	kfree(buddy->bits);
 	kfree(buddy->num_free);