On Wed, May 06, 2015 at 01:59:41PM +0200, Michal Hocko wrote: > On Tue 05-05-15 12:45:42, Vladimir Davydov wrote: > > Not all kmem allocations should be accounted to memcg. The following > > patch gives an example when accounting of a certain type of allocations > > to memcg can effectively result in a memory leak. > > > This patch adds the __GFP_NOACCOUNT flag which if passed to kmalloc > > and friends will force the allocation to go through the root > > cgroup. It will be used by the next patch. > > The name of the flag is way too generic. It is not clear that the > accounting is KMEMCG related. __GFP_NO_KMEMCG sounds better? > > I was going to suggest doing per-cache rather than gfp flag and that > would actually work just fine for the kmemleak as it uses its own cache > already. But the ida_simple_get would be trickier because it doesn't use > any special cache and more over only one user seem to have a problem so > this doesn't sound like a good fit. I don't think making this flag per-cache is an option either, but for another reason - it would not be possible to merge such a kmem cache with caches without this flag set. As a result, total memory pressure would increase, even for setups without kmem-active memory cgroups, which does not sound acceptable to me. > > So I do not object to opt-out for kmemcg accounting but I really think > the name should be changed. I named it __GFP_NOACCOUNT to match with __GFP_NOTRACK, which is a very specific flag too (kmemcheck), nevertheless it has a rather generic name. Anyways, what else apart from memcg can account kmem so that we have to mention KMEMCG in the flag name explicitly? 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>