[083/192] mm: memcg/slab: disable cache merging for KMALLOC_NORMAL caches

Commit Message

Andrew Morton June 29, 2021, 2:37 a.m. UTC

From: Waiman Long <[e-mail]>
Subject: mm: memcg/slab: disable cache merging for KMALLOC_NORMAL caches

The KMALLOC_NORMAL (kmalloc-<n>) caches are for unaccounted objects only
when CONFIG_MEMCG_KMEM is enabled.  To make sure that this condition
remains true, we will have to prevent KMALOC_NORMAL caches to merge with
other kmem caches.  This is now done by setting its refcount to -1 right
after its creation.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Waiman Long <[e-mail]>
Suggested-by: Roman Gushchin <[e-mail]>
Acked-by: Roman Gushchin <[e-mail]>
Reviewed-by: Shakeel Butt <[e-mail]>
Reviewed-by: Vlastimil Babka <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Pekka Enberg <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/slab_common.c |    7 +++++++
 1 file changed, 7 insertions(+)

Patch

--- a/mm/slab_common.c~mm-memcg-slab-disable-cache-merging-for-kmalloc_normal-caches
+++ a/mm/slab_common.c
@@ -856,6 +856,13 @@  new_kmalloc_cache(int idx, enum kmalloc_
 					kmalloc_info[idx].name[type],
 					kmalloc_info[idx].size, flags, 0,
 					kmalloc_info[idx].size);
+
+	/*
+	 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
+	 * KMALLOC_NORMAL caches.
+	 */
+	if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_NORMAL))
+		kmalloc_caches[type][idx]->refcount = -1;
 }
 
 /*