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. While here drop the spinlock_t element from the struct page when USE_SPLIT_PTE_PTLOCKS is not enabled. Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> # build-tested Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> --- This applies on v5.13-rc2. Changes in V2: - Dropped spinlock_t element from struct page Changes in V1: https://lore.kernel.org/linux-mm/1620618390-9999-1-git-send-email-anshuman.khandual@xxxxxxx/ include/linux/mm_types.h | 2 ++ include/linux/mm_types_task.h | 5 +++++ mm/memory.c | 2 +- 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 5aacc1c10a45..a0fd851c0a0c 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -152,10 +152,12 @@ struct page { struct mm_struct *pt_mm; /* x86 pgds only */ atomic_t pt_frag_refcount; /* powerpc */ }; +#if USE_SPLIT_PTE_PTLOCKS #if ALLOC_SPLIT_PTLOCKS spinlock_t *ptl; #else spinlock_t ptl; +#endif #endif }; struct { /* ZONE_DEVICE pages */ 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
