diff options
| -rw-r--r-- | Documentation/core-api/memory-allocation.rst | 17 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 6 | ||||
| -rw-r--r-- | mm/slab_common.c | 5 |
3 files changed, 18 insertions, 10 deletions
diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst index 5954ddf6ee13..1c58d883b273 100644 --- a/Documentation/core-api/memory-allocation.rst +++ b/Documentation/core-api/memory-allocation.rst @@ -170,7 +170,16 @@ should be used if a part of the cache might be copied to the userspace. After the cache is created kmem_cache_alloc() and its convenience wrappers can allocate memory from that cache. -When the allocated memory is no longer needed it must be freed. You can -use kvfree() for the memory allocated with `kmalloc`, `vmalloc` and -`kvmalloc`. The slab caches should be freed with kmem_cache_free(). And -don't forget to destroy the cache with kmem_cache_destroy(). +When the allocated memory is no longer needed it must be freed. + +Objects allocated by `kmalloc` can be freed by `kfree` or `kvfree`. Objects +allocated by `kmem_cache_alloc` can be freed with `kmem_cache_free`, `kfree` +or `kvfree`, where the latter two might be more convenient thanks to not +needing the kmem_cache pointer. + +The same rules apply to _bulk and _rcu flavors of freeing functions. + +Memory allocated by `vmalloc` can be freed with `vfree` or `kvfree`. +Memory allocated by `kvmalloc` can be freed with `kvfree`. +Caches created by `kmem_cache_create` should be freed with +`kmem_cache_destroy` only after freeing all the allocated objects first. diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 094321c17e48..dcd2cf1e8326 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -976,8 +976,10 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * either fall back to use of call_rcu() or rearrange the structure to * position the rcu_head structure into the first 4096 bytes. * - * Note that the allowable offset might decrease in the future, for example, - * to allow something like kmem_cache_free_rcu(). + * The object to be freed can be allocated either by kmalloc() or + * kmem_cache_alloc(). + * + * Note that the allowable offset might decrease in the future. * * The BUILD_BUG_ON check must not involve any function calls, hence the * checks are done in macros here. diff --git a/mm/slab_common.c b/mm/slab_common.c index 1522693295f5..607249785c07 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -989,12 +989,9 @@ EXPORT_SYMBOL(__kmalloc_node_track_caller); /** * kfree - free previously allocated memory - * @object: pointer returned by kmalloc. + * @object: pointer returned by kmalloc() or kmem_cache_alloc() * * If @object is NULL, no operation is performed. - * - * Don't free memory not originally allocated by kmalloc() - * or you will run into trouble. */ void kfree(const void *object) { |