From: Oscar Salvador <osalvador@xxxxxxx>
check_for_memory looks a bit confusing.
First of all, we have this:
if (N_MEMORY == N_NORMAL_MEMORY)
return;
Checking the ENUM declaration, looks like N_MEMORY canot be equal to
N_NORMAL_MEMORY.
I could not find where N_MEMORY is set to N_NORMAL_MEMORY, or the other
way around either, so unless I am missing something, this condition
will never evaluate to true.
It makes sense to get rid of it.
Moving forward, the operations whithin the loop look a bit confusing
as well.
We set N_HIGH_MEMORY unconditionally, and then we set N_NORMAL_MEMORY
in case we have CONFIG_HIGHMEM (N_NORMAL_MEMORY != N_HIGH_MEMORY)
and zone <= ZONE_NORMAL.
(N_HIGH_MEMORY falls back to N_NORMAL_MEMORY on !CONFIG_HIGHMEM systems,
and that is why we can just go ahead and set N_HIGH_MEMORY unconditionally)
Although this works, it is a bit subtle.
I think that this could be easier to follow:
First, we should only set N_HIGH_MEMORY in case we have
CONFIG_HIGHMEM.
And then we should set N_NORMAL_MEMORY in case zone <= ZONE_NORMAL,
without further checking whether we have CONFIG_HIGHMEM or not.
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
---
mm/page_alloc.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 839e0cc17f2c..6aa947f9e614 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6819,15 +6819,12 @@ static void check_for_memory(pg_data_t *pgdat, int nid)
{
enum zone_type zone_type;
- if (N_MEMORY == N_NORMAL_MEMORY)
- return;
-
for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
struct zone *zone = &pgdat->node_zones[zone_type];
if (populated_zone(zone)) {
- node_set_state(nid, N_HIGH_MEMORY);
- if (N_NORMAL_MEMORY != N_HIGH_MEMORY &&
- zone_type <= ZONE_NORMAL)
+ if (IS_ENABLED(CONFIG_HIGHMEM))
+ node_set_state(nid, N_HIGH_MEMORY);
+ if (zone_type <= ZONE_NORMAL)
node_set_state(nid, N_NORMAL_MEMORY);
break;
}
--
2.13.6
