diff options
| -rw-r--r-- | mm/slab.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c index d47d0e186973..3ad2f64998fd 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2206,8 +2206,17 @@ kmem_cache_create (const char *name, size_t size, size_t align, cachep->gfpflags |= GFP_DMA; cachep->buffer_size = size; - if (flags & CFLGS_OFF_SLAB) + if (flags & CFLGS_OFF_SLAB) { cachep->slabp_cache = kmem_find_general_cachep(slab_size, 0u); + /* + * This is a possibility for one of the malloc_sizes caches. + * But since we go off slab only for object size greater than + * PAGE_SIZE/8, and malloc_sizes gets created in ascending order, + * this should not happen at all. + * But leave a BUG_ON for some lucky dude. + */ + BUG_ON(!cachep->slabp_cache); + } cachep->ctor = ctor; cachep->dtor = dtor; cachep->name = name; @@ -2441,7 +2450,17 @@ int kmem_cache_destroy(struct kmem_cache *cachep) } EXPORT_SYMBOL(kmem_cache_destroy); -/* Get the memory for a slab management obj. */ +/* + * Get the memory for a slab management obj. + * For a slab cache when the slab descriptor is off-slab, slab descriptors + * always come from malloc_sizes caches. The slab descriptor cannot + * come from the same cache which is getting created because, + * when we are searching for an appropriate cache for these + * descriptors in kmem_cache_create, we search through the malloc_sizes array. + * If we are creating a malloc_sizes cache here it would not be visible to + * kmem_find_general_cachep till the initialization is complete. + * Hence we cannot have slabp_cache same as the original cache. + */ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp, int colour_off, gfp_t local_flags, int nodeid) @@ -3125,6 +3144,12 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects, if (slabp->inuse == 0) { if (l3->free_objects > l3->free_limit) { l3->free_objects -= cachep->num; + /* No need to drop any previously held + * lock here, even if we have a off-slab slab + * descriptor it is guaranteed to come from + * a different cache, refer to comments before + * alloc_slabmgmt. + */ slab_destroy(cachep, slabp); } else { list_add(&slabp->list, &l3->slabs_free); |