mm/list_lru.c: replace nr_node_ids for loop with for_each_node()
The functions used in the patch are in slowpath, which gets called
whenever alloc_super is called during mounts.
Though this should not make difference for the architectures with
sequential numa node ids, for the powerpc which can potentially have
sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17 is
common), this patch saves some unnecessary allocations for non existing
numa nodes.
Even without that saving, perhaps patch makes code more readable.
[vdavydov@parallels.com: take memcg_aware check outside for_each loop]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anton Blanchard <anton@samba.org>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Greg Kurz <gkurz@linux.vnet.ibm.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/list_lru.c b/mm/list_lru.c
index e1da19f..2823747 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -42,6 +42,10 @@
#ifdef CONFIG_MEMCG_KMEM
static inline bool list_lru_memcg_aware(struct list_lru *lru)
{
+ /*
+ * This needs node 0 to be always present, even
+ * in the systems supporting sparse numa ids.
+ */
return !!lru->node[0].memcg_lrus;
}
@@ -377,16 +381,20 @@
{
int i;
- for (i = 0; i < nr_node_ids; i++) {
- if (!memcg_aware)
- lru->node[i].memcg_lrus = NULL;
- else if (memcg_init_list_lru_node(&lru->node[i]))
+ if (!memcg_aware)
+ return 0;
+
+ for_each_node(i) {
+ if (memcg_init_list_lru_node(&lru->node[i]))
goto fail;
}
return 0;
fail:
- for (i = i - 1; i >= 0; i--)
+ for (i = i - 1; i >= 0; i--) {
+ if (!lru->node[i].memcg_lrus)
+ continue;
memcg_destroy_list_lru_node(&lru->node[i]);
+ }
return -ENOMEM;
}
@@ -397,7 +405,7 @@
if (!list_lru_memcg_aware(lru))
return;
- for (i = 0; i < nr_node_ids; i++)
+ for_each_node(i)
memcg_destroy_list_lru_node(&lru->node[i]);
}
@@ -409,16 +417,20 @@
if (!list_lru_memcg_aware(lru))
return 0;
- for (i = 0; i < nr_node_ids; i++) {
+ for_each_node(i) {
if (memcg_update_list_lru_node(&lru->node[i],
old_size, new_size))
goto fail;
}
return 0;
fail:
- for (i = i - 1; i >= 0; i--)
+ for (i = i - 1; i >= 0; i--) {
+ if (!lru->node[i].memcg_lrus)
+ continue;
+
memcg_cancel_update_list_lru_node(&lru->node[i],
old_size, new_size);
+ }
return -ENOMEM;
}
@@ -430,7 +442,7 @@
if (!list_lru_memcg_aware(lru))
return;
- for (i = 0; i < nr_node_ids; i++)
+ for_each_node(i)
memcg_cancel_update_list_lru_node(&lru->node[i],
old_size, new_size);
}
@@ -485,7 +497,7 @@
if (!list_lru_memcg_aware(lru))
return;
- for (i = 0; i < nr_node_ids; i++)
+ for_each_node(i)
memcg_drain_list_lru_node(&lru->node[i], src_idx, dst_idx);
}
@@ -522,7 +534,7 @@
if (!lru->node)
goto out;
- for (i = 0; i < nr_node_ids; i++) {
+ for_each_node(i) {
spin_lock_init(&lru->node[i].lock);
if (key)
lockdep_set_class(&lru->node[i].lock, key);