Minimally, node_load[] entries just need to be able to hold the maximum
value of HPAGE_PMD_NR, which is compile-time defined per-arch based on
PMD_SHIFT and PAGE_SHIFT. node_load[] is only written either via memset(),
or with via post-increment. struct collapse_control may be allocated
via kmalloc() in other collapse contexts, and MAX_NUMNODES may be
arbitrarily large. #define the underlying type of node_load[] based off
HPAGE_PMD_NR to avoid excessive memory allocated for this struct.
Fixes: 3b07f3bb225a ("mm/khugepaged: add struct collapse_control")
Link: https://lore.kernel.org/linux-mm/Ys2CeIm%2FQmQwWh9a@xxxxxxxxxx/
Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>
---
mm/khugepaged.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 69990dacde14..ecd28bfeab60 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -92,8 +92,11 @@ struct collapse_control {
bool is_khugepaged;
/* Num pages scanned per node */
- int node_load[MAX_NUMNODES];
-
+#if HPAGE_PMD_ORDER < 16
+ u16 node_load[MAX_NUMNODES];
+#else
+ u32 node_load[MAX_NUMNODES];
+#endif
/* Last target selected in hpage_collapse_find_target_node() */
int last_target_node;
};
--
2.37.0.170.g444d1eabd0-goog
