From e8753e416c7ec39812cf92608aa95640caca70fa Mon Sep 17 00:00:00 2001 From: Baoquan He Date: Sun, 13 Nov 2022 18:08:27 +0800 Subject: [PATCH] percpu: adjust the value of PERCPU_DYNAMIC_EARLY_SIZE LKP reported a build failure as below on the following patch "mm/slub, percpu: correct the calculation of early percpu allocation size" ~~~~~~ In file included from : In function 'alloc_kmem_cache_cpus', inlined from 'kmem_cache_open' at mm/slub.c:4340:6: >> >> include/linux/compiler_types.h:357:45: error: call to '__compiletime_assert_474' declared with attribute error: BUILD_BUG_ON failed: PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu) 357 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ~~~~~~ From the kernel config file provided by LKP, the building was made on arm64 with below Kconfig item enabled: CONFIG_ZONE_DMA=y CONFIG_SLUB_CPU_PARTIAL=y CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_SLUB_STATS=y CONFIG_ARM64_PAGE_SHIFT=16 CONFIG_ARM64_64K_PAGES=y Then we will have: NR_KMALLOC_TYPES:4 KMALLOC_SHIFT_HIGH:17 sizeof(struct kmem_cache_cpu):184 The product of them is 12512, which is bigger than PERCPU_DYNAMIC_EARLY_SIZE, 12K. Hence, the BUILD_BUG_ON in alloc_kmem_cache_cpus() is triggered. Earlier, in commit 099a19d91ca4 ("percpu: allow limited allocation before slab is online"), PERCPU_DYNAMIC_EARLY_SIZE was introduced and set to 12K which is equal to the then PERPCU_DYNAMIC_RESERVE. Later, in commit 1a4d76076cda ("percpu: implement asynchronous chunk population"), PERPCU_DYNAMIC_RESERVE was increased by 8K, while PERCPU_DYNAMIC_EARLY_SIZE was kept unchanged. So, here increase PERCPU_DYNAMIC_EARLY_SIZE by 8K too to accommodate to the slub's requirement. Reported-by: kernel test robot Signed-off-by: Baoquan He Acked-by: Dennis Zhou Signed-off-by: Vlastimil Babka --- include/linux/percpu.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/percpu.h b/include/linux/percpu.h index f1ec5ad..3dbb6fb 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -42,7 +42,7 @@ * larger than PERCPU_DYNAMIC_EARLY_SIZE. */ #define PERCPU_DYNAMIC_EARLY_SLOTS 128 -#define PERCPU_DYNAMIC_EARLY_SIZE (12 << 10) +#define PERCPU_DYNAMIC_EARLY_SIZE (20 << 10) /* * PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy -- 2.7.4