[PATCH 8/8] mm/slub, percpu: correct the calculation of early percpu allocation size

Baoquan He
2022-10-24T08:15:32Z

SLUB allocator relies on percpu allocator to initialize its ->cpu_slab
during early boot. For that, the dynamic chunk of percpu which serves
the early allocation need be large enough to satisfy the kmalloc
creation.

However, the current BUILD_BUG_ON() in alloc_kmem_cache_cpus() doesn't
consider the kmalloc array with NR_KMALLOC_TYPES length. Fix that
with correct calculation.

Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
mm/slub.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 157527d7101b..8ac3bb9a122a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4017,7 +4017,8 @@ init_kmem_cache_node(struct kmem_cache_node *n)
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
- KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
+ NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH *
+ sizeof(struct kmem_cache_cpu));

/*
* Must align to double word boundary for the double cmpxchg
--
2.34.1