On Mon, Jan 26, 2015 at 01:55:14PM -0600, Christoph Lameter wrote: > On Mon, 26 Jan 2015, Vladimir Davydov wrote: > > > Hmm, why? The return value has existed since this function was > > introduced, but nobody seems to have ever used it outside the slab core. > > Besides, this check is racy, so IMO we shouldn't encourage users of the > > API to rely on it. That said, I believe we should drop the return value > > for now. If anybody ever needs it, we can reintroduce it. > > The check is only racy if you have concurrent users. It is not racy if a > subsystem shuts down access to the slabs and then checks if everything is > clean before closing the cache. > > Slab creation and destruction are not serialized. It is the responsibility > of the subsystem to make sure that there are no concurrent users and that > there are no objects remaining before destroying a slab. Right, but I just don't see why a subsystem using a kmem_cache would need to check whether there are any objects left in the cache. I mean, it should somehow keep track of the objects it's allocated anyway, e.g. by linking them in a list. That means it must already have a way to check if it is safe to destroy its cache or not. Suppose we leave the return value as is. A subsystem, right before going to destroy a cache, calls kmem_cache_shrink, which returns 1 (slab is not empty). What is it supposed to do then? Thanks, Vladimir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>