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 --- mm/slab_common.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'mm/slab_common.c') diff --git a/mm/slab_common.c b/mm/slab_common.c index 0042fb2730d1..af0f370fe7a2 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -143,8 +143,10 @@ int slab_unmergeable(struct kmem_cache *s) if (s->ctor) return 1; +#ifdef CONFIG_HARDENED_USERCOPY if (s->usersize) return 1; +#endif /* * We may have set a slab to be unmergeable during bootstrap. @@ -223,8 +225,10 @@ static struct kmem_cache *create_cache(const char *name, s->size = s->object_size = object_size; s->align = align; s->ctor = ctor; +#ifdef CONFIG_HARDENED_USERCOPY s->useroffset = useroffset; s->usersize = usersize; +#endif err = __kmem_cache_create(s, flags); if (err) @@ -317,7 +321,8 @@ kmem_cache_create_usercopy(const char *name, flags &= CACHE_CREATE_MASK; /* Fail closed on bad usersize of useroffset values. */ - if (WARN_ON(!usersize && useroffset) || + if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || + WARN_ON(!usersize && useroffset) || WARN_ON(size < usersize || size - usersize < useroffset)) usersize = useroffset = 0; @@ -595,8 +600,8 @@ void kmem_dump_obj(void *object) ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; pr_cont(" pointer offset %lu", ptroffset); } - if (kp.kp_slab_cache && kp.kp_slab_cache->usersize) - pr_cont(" size %u", kp.kp_slab_cache->usersize); + if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) + pr_cont(" size %u", kp.kp_slab_cache->object_size); if (kp.kp_ret) pr_cont(" allocated at %pS\n", kp.kp_ret); else @@ -640,8 +645,10 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name, align = max(align, size); s->align = calculate_alignment(flags, align, size); +#ifdef CONFIG_HARDENED_USERCOPY s->useroffset = useroffset; s->usersize = usersize; +#endif err = __kmem_cache_create(s, flags); -- cgit v1.2.3 From 2f7c1c1396b587e8cfe18a1f0d628cedaae56b6a Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 15 Nov 2022 18:19:28 +0100 Subject: 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 Acked-by: Mike Rapoport Reviewed-by: Christoph Lameter --- include/linux/slab.h | 9 +++++++-- mm/slab_common.c | 10 ++++++++-- 2 files changed, 15 insertions(+), 4 deletions(-) (limited to 'mm/slab_common.c') diff --git a/include/linux/slab.h b/include/linux/slab.h index 45efc6c553b8..ae2d19ec8467 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -336,12 +336,17 @@ enum kmalloc_cache_type { #endif #ifndef CONFIG_MEMCG_KMEM KMALLOC_CGROUP = KMALLOC_NORMAL, -#else - KMALLOC_CGROUP, #endif +#ifdef CONFIG_SLUB_TINY + KMALLOC_RECLAIM = KMALLOC_NORMAL, +#else KMALLOC_RECLAIM, +#endif #ifdef CONFIG_ZONE_DMA KMALLOC_DMA, +#endif +#ifdef CONFIG_MEMCG_KMEM + KMALLOC_CGROUP, #endif NR_KMALLOC_TYPES }; diff --git a/mm/slab_common.c b/mm/slab_common.c index af0f370fe7a2..012fc75d3ffa 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -773,10 +773,16 @@ 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, \ @@ -862,7 +868,7 @@ 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()) { -- cgit v1.2.3