From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slab: combine kmalloc_caches and kmalloc_dma_caches Patch series "kmalloc-reclaimable caches", v4. As discussed at LSF/MM [1] here's a patchset that introduces kmalloc-reclaimable caches (more details in the second patch) and uses them for dcache external names. That allows us to repurpose the NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series. With patch 3/6, dcache external names are allocated from kmalloc-rcl-* caches, eliminating the need for manual accounting. More importantly, it also ensures the reclaimable kmalloc allocations are grouped in pages separate from the regular kmalloc allocations. The need for proper accounting of dcache external names has shown it's easy for misbehaving process to allocate lots of them, causing premature OOMs. Without the added grouping, it's likely that a similar workload can interleave the dcache external names allocations with regular kmalloc allocations (note: I haven't searched myself for an example of such regular kmalloc allocation, but I would be very surprised if there wasn't some). A pathological case would be e.g. one 64byte regular allocations with 63 external dcache names in a page (64x64=4096), which means the page is not freed even after reclaiming after all dcache names, and the process can thus "steal" the whole page with single 64byte allocation. If other kmalloc users similar to dcache external names become identified, they can also benefit from the new functionality simply by adding __GFP_RECLAIMABLE to the kmalloc calls. Side benefits of the patchset (that could be also merged separately) include removed branch for detecting __GFP_DMA kmalloc(), and shortening kmalloc cache names in /proc/slabinfo output. The latter is potentially an ABI break in case there are tools parsing the names and expecting the values to be in bytes. This is how /proc/slabinfo looks like after booting in virtme: ... kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0 ... kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0 kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0 kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0 kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0 kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0 kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0 ... /proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter: ... nr_slab_reclaimable 2817 nr_slab_unreclaimable 1781 ... nr_kernel_misc_reclaimable 0 ... /proc/meminfo with new KReclaimable counter: ... Shmem: 564 kB KReclaimable: 11260 kB Slab: 18368 kB SReclaimable: 11260 kB SUnreclaim: 7108 kB KernelStack: 1248 kB ... This patch (of 6): The kmalloc caches currently mainain separate (optional) array kmalloc_dma_caches for __GFP_DMA allocations. There are tests for __GFP_DMA in the allocation hotpaths. We can avoid the branches by combining kmalloc_caches and kmalloc_dma_caches into a single two-dimensional array where the outer dimension is cache "type". This will also allow to add kmalloc-reclaimable caches as a third type. Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Christoph Lameter <cl@xxxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Laura Abbott <labbott@xxxxxxxxxx> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> Cc: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/slab.h | 42 ++++++++++++++++++++++++++++++----------- mm/slab.c | 4 +-- mm/slab_common.c | 31 +++++++++++------------------- mm/slub.c | 13 ++++++------ 4 files changed, 52 insertions(+), 38 deletions(-) --- a/include/linux/slab.h~mm-slab-combine-kmalloc_caches-and-kmalloc_dma_caches +++ a/include/linux/slab.h @@ -295,12 +295,29 @@ static inline void __check_heap_object(c #define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \ (KMALLOC_MIN_SIZE) : 16) +enum kmalloc_cache_type { + KMALLOC_NORMAL = 0, +#ifdef CONFIG_ZONE_DMA + KMALLOC_DMA, +#endif + NR_KMALLOC_TYPES +}; + #ifndef CONFIG_SLOB -extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; +extern struct kmem_cache * +kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1]; + +static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags) +{ + int is_dma = 0; + #ifdef CONFIG_ZONE_DMA -extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1]; + is_dma = !!(flags & __GFP_DMA); #endif + return is_dma; +} + /* * Figure out which kmalloc slab an allocation of a certain size * belongs to. @@ -501,18 +518,20 @@ static __always_inline void *kmalloc_lar static __always_inline void *kmalloc(size_t size, gfp_t flags) { if (__builtin_constant_p(size)) { +#ifndef CONFIG_SLOB + unsigned int index; +#endif if (size > KMALLOC_MAX_CACHE_SIZE) return kmalloc_large(size, flags); #ifndef CONFIG_SLOB - if (!(flags & GFP_DMA)) { - unsigned int index = kmalloc_index(size); + index = kmalloc_index(size); - if (!index) - return ZERO_SIZE_PTR; + if (!index) + return ZERO_SIZE_PTR; - return kmem_cache_alloc_trace(kmalloc_caches[index], - flags, size); - } + return kmem_cache_alloc_trace( + kmalloc_caches[kmalloc_type(flags)][index], + flags, size); #endif } return __kmalloc(size, flags); @@ -542,13 +561,14 @@ static __always_inline void *kmalloc_nod { #ifndef CONFIG_SLOB if (__builtin_constant_p(size) && - size <= KMALLOC_MAX_CACHE_SIZE && !(flags & GFP_DMA)) { + size <= KMALLOC_MAX_CACHE_SIZE) { unsigned int i = kmalloc_index(size); if (!i) return ZERO_SIZE_PTR; - return kmem_cache_alloc_node_trace(kmalloc_caches[i], + return kmem_cache_alloc_node_trace( + kmalloc_caches[kmalloc_type(flags)][i], flags, node, size); } #endif --- a/mm/slab.c~mm-slab-combine-kmalloc_caches-and-kmalloc_dma_caches +++ a/mm/slab.c @@ -1288,7 +1288,7 @@ void __init kmem_cache_init(void) * Initialize the caches that provide memory for the kmem_cache_node * structures first. Without this, further allocations will bug. */ - kmalloc_caches[INDEX_NODE] = create_kmalloc_cache( + kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache( kmalloc_info[INDEX_NODE].name, kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS, 0, kmalloc_size(INDEX_NODE)); @@ -1304,7 +1304,7 @@ void __init kmem_cache_init(void) for_each_online_node(nid) { init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid); - init_list(kmalloc_caches[INDEX_NODE], + init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE], &init_kmem_cache_node[SIZE_NODE + nid], nid); } } --- a/mm/slab_common.c~mm-slab-combine-kmalloc_caches-and-kmalloc_dma_caches +++ a/mm/slab_common.c @@ -973,14 +973,10 @@ struct kmem_cache *__init create_kmalloc return s; } -struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __ro_after_init; +struct kmem_cache * +kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init; EXPORT_SYMBOL(kmalloc_caches); -#ifdef CONFIG_ZONE_DMA -struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1] __ro_after_init; -EXPORT_SYMBOL(kmalloc_dma_caches); -#endif - /* * Conversion table for small slabs sizes / 8 to the index in the * kmalloc array. This is necessary for slabs < 192 since we have non power @@ -1040,12 +1036,7 @@ struct kmem_cache *kmalloc_slab(size_t s index = fls(size - 1); } -#ifdef CONFIG_ZONE_DMA - if (unlikely((flags & GFP_DMA))) - return kmalloc_dma_caches[index]; - -#endif - return kmalloc_caches[index]; + return kmalloc_caches[kmalloc_type(flags)][index]; } /* @@ -1119,7 +1110,8 @@ void __init setup_kmalloc_cache_index_ta static void __init new_kmalloc_cache(int idx, slab_flags_t flags) { - kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name, + kmalloc_caches[KMALLOC_NORMAL][idx] = create_kmalloc_cache( + kmalloc_info[idx].name, kmalloc_info[idx].size, flags, 0, kmalloc_info[idx].size); } @@ -1132,9 +1124,10 @@ static void __init new_kmalloc_cache(int void __init create_kmalloc_caches(slab_flags_t flags) { int i; + int type = KMALLOC_NORMAL; for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { - if (!kmalloc_caches[i]) + if (!kmalloc_caches[type][i]) new_kmalloc_cache(i, flags); /* @@ -1142,9 +1135,9 @@ void __init create_kmalloc_caches(slab_f * These have to be created immediately after the * earlier power of two caches */ - if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6) + if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[type][1] && i == 6) new_kmalloc_cache(1, flags); - if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7) + if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[type][2] && i == 7) new_kmalloc_cache(2, flags); } @@ -1153,7 +1146,7 @@ void __init create_kmalloc_caches(slab_f #ifdef CONFIG_ZONE_DMA for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { - struct kmem_cache *s = kmalloc_caches[i]; + struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i]; if (s) { unsigned int size = kmalloc_size(i); @@ -1161,8 +1154,8 @@ void __init create_kmalloc_caches(slab_f "dma-kmalloc-%u", size); BUG_ON(!n); - kmalloc_dma_caches[i] = create_kmalloc_cache(n, - size, SLAB_CACHE_DMA | flags, 0, 0); + kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( + n, size, SLAB_CACHE_DMA | flags, 0, 0); } } #endif --- a/mm/slub.c~mm-slab-combine-kmalloc_caches-and-kmalloc_dma_caches +++ a/mm/slub.c @@ -4689,6 +4689,7 @@ static int list_locations(struct kmem_ca static void __init resiliency_test(void) { u8 *p; + int type = KMALLOC_NORMAL; BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10); @@ -4701,7 +4702,7 @@ static void __init resiliency_test(void) pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n", p + 16); - validate_slab_cache(kmalloc_caches[4]); + validate_slab_cache(kmalloc_caches[type][4]); /* Hmmm... The next two are dangerous */ p = kzalloc(32, GFP_KERNEL); @@ -4710,33 +4711,33 @@ static void __init resiliency_test(void) p); pr_err("If allocated object is overwritten then not detectable\n\n"); - validate_slab_cache(kmalloc_caches[5]); + validate_slab_cache(kmalloc_caches[type][5]); p = kzalloc(64, GFP_KERNEL); p += 64 + (get_cycles() & 0xff) * sizeof(void *); *p = 0x56; pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n", p); pr_err("If allocated object is overwritten then not detectable\n\n"); - validate_slab_cache(kmalloc_caches[6]); + validate_slab_cache(kmalloc_caches[type][6]); pr_err("\nB. Corruption after free\n"); p = kzalloc(128, GFP_KERNEL); kfree(p); *p = 0x78; pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p); - validate_slab_cache(kmalloc_caches[7]); + validate_slab_cache(kmalloc_caches[type][7]); p = kzalloc(256, GFP_KERNEL); kfree(p); p[50] = 0x9a; pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p); - validate_slab_cache(kmalloc_caches[8]); + validate_slab_cache(kmalloc_caches[type][8]); p = kzalloc(512, GFP_KERNEL); kfree(p); p[512] = 0xab; pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p); - validate_slab_cache(kmalloc_caches[9]); + validate_slab_cache(kmalloc_caches[type][9]); } #else #ifdef CONFIG_SYSFS _
