Re: [RFC PATCH 1/3] kmemleak: Allow partial freeing of memory blocks

Pekka Enberg
2009-07-07T06:29:35Z

On Mon, 2009-07-06 at 11:51 +0100, Catalin Marinas wrote:
> @@ -552,8 +558,29 @@ static void delete_object(unsigned long ptr)
> */
> spin_lock_irqsave(&object->lock, flags);
> object->flags &= ~OBJECT_ALLOCATED;
> + start = object->pointer;
> + end = object->pointer + object->size;
> + min_count = object->min_count;
> spin_unlock_irqrestore(&object->lock, flags);
> put_object(object);
> +
> + if (!size)
> + return;
> +
> + /*
> + * Partial freeing. Just create one or two objects that may result
> + * from the memory block split.
> + */
> + if (in_atomic())
> + gfp_flags = GFP_ATOMIC;
> + else
> + gfp_flags = GFP_KERNEL;

Are you sure we can do this? There's a big fat comment on top of
in_atomic() that suggest this is not safe. Why do we need to create the
object here anyway and not in the _alloc_ paths where gfp flags are
explicitly passed?

> +
> + if (ptr > start)
> + create_object(start, ptr - start, min_count, gfp_flags);
> + if (ptr + size < end)
> + create_object(ptr + size, end - ptr - size, min_count,
> + gfp_flags);
> }
>
> /*