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

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Date:   Mon, 24 Oct 2022 16:14:35 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Baoquan He <bhe@...hat.com>, Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>
Subject: [PATCH 8/8] mm/slub, percpu: correct the calculation of early percpu allocation size

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@...hat.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Pekka Enberg <penberg@...nel.org>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@...il.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