Messages in this thread Patch in this message | | | From | Glauber Costa <> | Subject | [PATCH v4 12/25] sl[au]b: always get the cache from its page in kfree | Date | Mon, 18 Jun 2012 14:28:05 +0400 |
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struct page already have this information. If we start chaining caches, this information will always be more trustworthy than whatever is passed into the function
A parent pointer is added to the slub structure, so we can make sure the freeing comes from either the right slab, or from its rightful parent.
[ v3: added parent testing with VM_BUG_ON ]
Signed-off-by: Glauber Costa <glommer@parallels.com> CC: Christoph Lameter <cl@linux.com> CC: Pekka Enberg <penberg@cs.helsinki.fi> --- mm/slab.c | 5 ++++- mm/slab.h | 10 ++++++++++ mm/slub.c | 3 ++- 3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c index c30a61c..3783a6a 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3712,9 +3712,12 @@ EXPORT_SYMBOL(__kmalloc); * Free an object which was previously allocated from this * cache. */ -void kmem_cache_free(struct kmem_cache *cachep, void *objp) +void kmem_cache_free(struct kmem_cache *s, void *objp) { unsigned long flags; + struct kmem_cache *cachep = virt_to_cache(objp); + + VM_BUG_ON(!((s == cachep) | slab_is_parent(s, cachep))); local_irq_save(flags); debug_check_no_locks_freed(objp, cachep->size); diff --git a/mm/slab.h b/mm/slab.h index 1781580..0a3e712 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -63,4 +63,14 @@ static inline bool cache_match_memcg(struct kmem_cache *cachep, } void __init memcg_slab_register_all(void); + +static inline bool slab_is_parent(struct kmem_cache *s, + struct kmem_cache *candidate) +{ +#if defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM) && defined(CONFIG_DEBUG_VM) + return candidate == s->memcg_params.parent; +#else + return false; +#endif +} #endif diff --git a/mm/slub.c b/mm/slub.c index ca4b8e0..e685cfa 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2597,7 +2597,8 @@ void kmem_cache_free(struct kmem_cache *s, void *x) page = virt_to_head_page(x); - slab_free(s, page, x, _RET_IP_); + VM_BUG_ON(!((page->slab == s) | slab_is_parent(page->slab, s))); + slab_free(page->slab, page, x, _RET_IP_); trace_kmem_cache_free(_RET_IP_, x); } -- 1.7.10.2
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