linux-kernel - [PATCH 06/12] mm, slub: don't create kmalloc-rcl caches with CONFIG_SLUB

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Date:   Mon, 21 Nov 2022 18:11:56 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Pekka Enberg <penberg@...nel.org>
Cc:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>, patches@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 06/12] mm, slub: don't create kmalloc-rcl caches with CONFIG_SLUB_TINY

Distinguishing kmalloc(__GFP_RECLAIMABLE) can help against fragmentation
by grouping pages by mobility, but on tiny systems the extra memory
overhead of separate set of kmalloc-rcl caches will probably be worse,
and mobility grouping likely disabled anyway.

Thus with CONFIG_SLUB_TINY, don't create kmalloc-rcl caches and use the
regular ones.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 include/linux/slab.h |  4 ++++
 mm/slab_common.c     | 10 ++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 45efc6c553b8..3ce9474c90ab 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -339,7 +339,11 @@ enum kmalloc_cache_type {
 #else
 	KMALLOC_CGROUP,
 #endif
+#ifndef CONFIG_SLUB_TINY
 	KMALLOC_RECLAIM,
+#else
+	KMALLOC_RECLAIM = KMALLOC_NORMAL,
+#endif
 #ifdef CONFIG_ZONE_DMA
 	KMALLOC_DMA,
 #endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a8cb5de255fc..907d52963806 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -770,10 +770,16 @@ EXPORT_SYMBOL(kmalloc_size_roundup);
 #define KMALLOC_CGROUP_NAME(sz)
 #endif
 
+#ifndef CONFIG_SLUB_TINY
+#define KMALLOC_RCL_NAME(sz)	.name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
+#else
+#define KMALLOC_RCL_NAME(sz)
+#endif
+
 #define INIT_KMALLOC_INFO(__size, __short_size)			\
 {								\
 	.name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,	\
-	.name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size,	\
+	KMALLOC_RCL_NAME(__short_size)				\
 	KMALLOC_CGROUP_NAME(__short_size)			\
 	KMALLOC_DMA_NAME(__short_size)				\
 	.size = __size,						\
@@ -859,7 +865,7 @@ void __init setup_kmalloc_cache_index_table(void)
 static void __init
 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
 {
-	if (type == KMALLOC_RECLAIM) {
+	if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
 		flags |= SLAB_RECLAIM_ACCOUNT;
 	} else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
 		if (mem_cgroup_kmem_disabled()) {
-- 
2.38.1