From 346907ceb9d11b9e22677c142b45ff50dd20a66a Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Wed, 16 Nov 2022 15:56:32 +0100 Subject: mm, slab: ignore hardened usercopy parameters when disabled With CONFIG_HARDENED_USERCOPY not enabled, there are no __check_heap_object() checks happening that would use the struct kmem_cache useroffset and usersize fields. Yet the fields are still initialized, preventing merging of otherwise compatible caches. Also the fields contribute to struct kmem_cache size unnecessarily when unused. Thus #ifdef them out completely when CONFIG_HARDENED_USERCOPY is disabled. In kmem_dump_obj() print object_size instead of usersize, as that's actually the intention. In a quick virtme boot test, this has reduced the number of caches in /proc/slabinfo from 131 to 111. Cc: Kees Cook Signed-off-by: Vlastimil Babka Acked-by: Roman Gushchin Acked-by: Mike Rapoport Reviewed-by: Christoph Lameter --- include/linux/slab_def.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/slab_def.h') diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h index f0ffad6a3365..5834bad8ad78 100644 --- a/include/linux/slab_def.h +++ b/include/linux/slab_def.h @@ -80,8 +80,10 @@ struct kmem_cache { unsigned int *random_seq; #endif +#ifdef CONFIG_HARDENED_USERCOPY unsigned int useroffset; /* Usercopy region offset */ unsigned int usersize; /* Usercopy region size */ +#endif struct kmem_cache_node *node[MAX_NUMNODES]; }; -- cgit v1.2.3