[PATCH] mm/thp: Make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS

From: Anshuman Khandual
Date: Sun May 09 2021 - 23:46:00 EST


Split ptlocks need not be defined and allocated unless they are being used.
ALLOC_SPLIT_PTLOCKS is inherently dependent on USE_SPLIT_PTE_PTLOCKS. This
just makes it explicit and clear.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
include/linux/mm_types_task.h | 5 +++++
mm/memory.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm_types_task.h b/include/linux/mm_types_task.h
index c1bc6731125c..1b222f8039d1 100644
--- a/include/linux/mm_types_task.h
+++ b/include/linux/mm_types_task.h
@@ -22,7 +22,12 @@
#define USE_SPLIT_PTE_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
#define USE_SPLIT_PMD_PTLOCKS (USE_SPLIT_PTE_PTLOCKS && \
IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
+
+#if USE_SPLIT_PTE_PTLOCKS
#define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
+#else
+#define ALLOC_SPLIT_PTLOCKS 0
+#endif

/*
* The per task VMA cache array:
diff --git a/mm/memory.c b/mm/memory.c
index 730daa00952b..9c3b63f11aee 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5250,7 +5250,7 @@ long copy_huge_page_from_user(struct page *dst_page,
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */

-#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
+#if ALLOC_SPLIT_PTLOCKS

static struct kmem_cache *page_ptl_cachep;

--
2.20.1