From 40f9fb8cffc6a20ae269e3b43dfba7a4f65d7f50 Mon Sep 17 00:00:00 2001 From: Mahendran Ganesh Date: Fri, 12 Dec 2014 16:57:01 -0800 Subject: [PATCH] mm/zsmalloc: support allocating obj with size of ZS_MAX_ALLOC_SIZE I sent a patch [1] for unnecessary check in zsmalloc. And Minchan Kim found zsmalloc even does not support allocating an obj with the size of ZS_MAX_ALLOC_SIZE in some situations. For example: In system with 64KB PAGE_SIZE and 32 bit of physical addr. Then: ZS_MIN_ALLOC_SIZE is 32 bytes which is calculated by: MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) ZS_MAX_ALLOC_SIZE is 64KB(in current code, is PAGE_SIZE) ZS_SIZE_CLASS_DELTA is 256 bytes So, ZS_SIZE_CLASSES = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1 = 256 In zs_create_pool(), the max size obj which can be allocated will be: ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA = 32 + 255*256 = 65312 We can see that 65312 < 65536 (ZS_MAX_ALLOC_SIZE). So we can NOT allocate objs with size ZS_MAX_ALLOC_SIZE(65536) which we promise upper users we can do. [1] http://lkml.iu.edu/hypermail/linux/kernel/1411.2/03835.html [2] http://lkml.iu.edu/hypermail/linux/kernel/1411.2/04534.html This patch fixes this issue by dynamiclly calculating zs_size_classes when module is loaded, allocates buffer with size ZS_MAX_ALLOC_SIZE. Then the max obj(size is ZS_MAX_ALLOC_SIZE) can be stored in it. [akpm@linux-foundation.org: restore ZS_SIZE_CLASSES to fix bisectability] Signed-off-by: Mahendran Ganesh Suggested-by: Minchan Kim Cc: Nitin Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/zsmalloc.c | 38 ++++++++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 6 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 83ecdb675c40..61e180931ca8 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -170,6 +170,11 @@ enum fullness_group { ZS_FULL }; +/* + * number of size_classes + */ +static int zs_size_classes; + /* * We assign a page to ZS_ALMOST_EMPTY fullness group when: * n <= N / f, where @@ -214,7 +219,7 @@ struct link_free { }; struct zs_pool { - struct size_class *size_class[ZS_SIZE_CLASSES]; + struct size_class **size_class; gfp_t flags; /* allocation flags used when growing pool */ atomic_long_t pages_allocated; @@ -785,7 +790,7 @@ static inline int __zs_cpu_up(struct mapping_area *area) */ if (area->vm_buf) return 0; - area->vm_buf = (char *)__get_free_page(GFP_KERNEL); + area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL); if (!area->vm_buf) return -ENOMEM; return 0; @@ -793,8 +798,7 @@ static inline int __zs_cpu_up(struct mapping_area *area) static inline void __zs_cpu_down(struct mapping_area *area) { - if (area->vm_buf) - free_page((unsigned long)area->vm_buf); + kfree(area->vm_buf); area->vm_buf = NULL; } @@ -912,6 +916,17 @@ static int zs_register_cpu_notifier(void) return notifier_to_errno(ret); } +static void init_zs_size_classes(void) +{ + int nr; + + nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1; + if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA) + nr += 1; + + zs_size_classes = nr; +} + static void __exit zs_exit(void) { #ifdef CONFIG_ZPOOL @@ -929,6 +944,8 @@ static int __init zs_init(void) return ret; } + init_zs_size_classes(); + #ifdef CONFIG_ZPOOL zpool_register_driver(&zs_zpool_driver); #endif @@ -972,11 +989,18 @@ struct zs_pool *zs_create_pool(gfp_t flags) if (!pool) return NULL; + pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *), + GFP_KERNEL); + if (!pool->size_class) { + kfree(pool); + return NULL; + } + /* * Iterate reversly, because, size of size_class that we want to use * for merging should be larger or equal to current size. */ - for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { + for (i = zs_size_classes - 1; i >= 0; i--) { int size; int pages_per_zspage; struct size_class *class; @@ -1029,7 +1053,7 @@ void zs_destroy_pool(struct zs_pool *pool) { int i; - for (i = 0; i < ZS_SIZE_CLASSES; i++) { + for (i = 0; i < zs_size_classes; i++) { int fg; struct size_class *class = pool->size_class[i]; @@ -1047,6 +1071,8 @@ void zs_destroy_pool(struct zs_pool *pool) } kfree(class); } + + kfree(pool->size_class); kfree(pool); } EXPORT_SYMBOL_GPL(zs_destroy_pool); -- 2.20.1