With enabled slub_debug alloc_calls_show will try to track location and user of slab object on each online node, kmem_cache_node structure shouldn't be freed till there is the last reference to sysfs file. Fixes the following panic: [43963.463055] BUG: unable to handle kernel [43963.463090] NULL pointer dereference at 0000000000000020 [43963.463146] IP: [<ffffffff811c6959>] list_locations+0x169/0x4e0 [43963.463185] PGD 257304067 PUD 438456067 PMD 0 [43963.463220] Oops: 0000 [#1] SMP [43963.463850] CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted 3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30 [43963.463913] Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011 [43963.463976] task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000 [43963.464036] RIP: 0010:[<ffffffff811c6959>] [<ffffffff811c6959>] list_locations+0x169/0x4e0 [43963.464725] Call Trace: [43963.464756] [<ffffffff811c6d1d>] alloc_calls_show+0x1d/0x30 [43963.464793] [<ffffffff811c15ab>] slab_attr_show+0x1b/0x30 [43963.464829] [<ffffffff8125d27a>] sysfs_read_file+0x9a/0x1a0 [43963.464865] [<ffffffff811e3c6c>] vfs_read+0x9c/0x170 [43963.464900] [<ffffffff811e4798>] SyS_read+0x58/0xb0 [43963.464936] [<ffffffff81612d49>] system_call_fastpath+0x16/0x1b [43963.464970] Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89 45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85 c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10 [43963.465119] RIP [<ffffffff811c6959>] list_locations+0x169/0x4e0 [43963.465155] RSP <ffff88037f8dbe28> [43963.465185] CR2: 0000000000000020 Separated nodes structures freeing into __kmem_cache_free_nodes and use it at kmem_cache_release. Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> --- v2: Down with SLAB_SUPPORTS_SYSFS thing. v3: Moved sysfs_slab_remove inside shutdown_cache v4: Reworked all to shutdown & free caches on object->release() v5: Made separate __kmem_cache_free_nodes function and call it on release. mm/slab.c | 12 +++++++++--- mm/slab.h | 1 + mm/slab_common.c | 1 + mm/slob.c | 4 ++++ mm/slub.c | 8 ++++---- 5 files changed, 19 insertions(+), 7 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 6ecc697..3ccdf3c 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2276,6 +2276,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) err = setup_cpu_cache(cachep, gfp); if (err) { __kmem_cache_shutdown(cachep); + __kmem_cache_free_nodes(cachep); return err; } @@ -2414,8 +2415,6 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate) int __kmem_cache_shutdown(struct kmem_cache *cachep) { - int i; - struct kmem_cache_node *n; int rc = __kmem_cache_shrink(cachep, false); if (rc) @@ -2423,6 +2422,14 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep) free_percpu(cachep->cpu_cache); + return 0; +} + +void __kmem_cache_free_nodes(struct kmem_cache *cachep) +{ + int i; + struct kmem_cache_node *n; + /* NUMA: free the node structures */ for_each_kmem_cache_node(cachep, i, n) { kfree(n->shared); @@ -2430,7 +2437,6 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep) kfree(n); cachep->node[i] = NULL; } - return 0; } /* diff --git a/mm/slab.h b/mm/slab.h index 834ad24..b1a6576 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -140,6 +140,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size, #define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS) int __kmem_cache_shutdown(struct kmem_cache *); +void __kmem_cache_free_nodes(struct kmem_cache *); int __kmem_cache_shrink(struct kmem_cache *, bool); void slab_kmem_cache_release(struct kmem_cache *); diff --git a/mm/slab_common.c b/mm/slab_common.c index b50aef0..0bc2da3 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -693,6 +693,7 @@ static inline int shutdown_memcg_caches(struct kmem_cache *s, void slab_kmem_cache_release(struct kmem_cache *s) { + __kmem_cache_free_nodes(s); destroy_memcg_params(s); kfree_const(s->name); kmem_cache_free(kmem_cache, s); diff --git a/mm/slob.c b/mm/slob.c index 17e8f8c..242d77d 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -630,6 +630,10 @@ int __kmem_cache_shutdown(struct kmem_cache *c) return 0; } +void __kmem_cache_free_nodes(struct kmem_cache *c) +{ +} + int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate) { return 0; diff --git a/mm/slub.c b/mm/slub.c index 2e1355a..d05bcea 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3173,7 +3173,7 @@ static void early_kmem_cache_node_alloc(int node) __add_partial(n, page, DEACTIVATE_TO_HEAD); } -static void free_kmem_cache_nodes(struct kmem_cache *s) +void __kmem_cache_free_nodes(struct kmem_cache *s) { int node; struct kmem_cache_node *n; @@ -3199,7 +3199,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) GFP_KERNEL, node); if (!n) { - free_kmem_cache_nodes(s); + __kmem_cache_free_nodes(s); return 0; } @@ -3405,7 +3405,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags) if (alloc_kmem_cache_cpus(s)) return 0; - free_kmem_cache_nodes(s); + __kmem_cache_free_nodes(s); error: if (flags & SLAB_PANIC) panic("Cannot create slab %s size=%lu realsize=%u " @@ -3477,7 +3477,7 @@ static inline int kmem_cache_close(struct kmem_cache *s) return 1; } free_percpu(s->cpu_slab); - free_kmem_cache_nodes(s); + __kmem_cache_free_nodes(s); return 0; } -- 2.7.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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