On Thu, Mar 31, 2016 at 01:53:14PM +0300, Nikolay Borisov wrote: > > > On 03/28/2016 08:26 AM, js1304@xxxxxxxxx wrote: > > From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > > > Major kmem_cache metadata in slab subsystem is synchronized with > > the slab_mutex. In SLAB, if some of them is changed, node's shared > > array cache would be freed and re-populated. If __kmem_cache_shrink() > > is called at the same time, it will call drain_array() with n->shared > > without holding node lock so problem can happen. > > > > We can fix this small theoretical race condition by holding node lock > > in drain_array(), but, holding a slab_mutex in kmem_cache_shrink() > > looks more appropriate solution because stable state would make things > > less error-prone and this is not performance critical path. > > > > In addtion, annotate on SLAB functions. > > Just a nit but would it not be better instead of doing comment-style > annotation to use lockdep_assert_held/_once. In both cases for someone > to understand what locks have to be held will go and read the source. In > my mind it's easier to miss a comment line, rather than the > lockdep_assert. Furthermore in case lockdep is enabled a locking > violation would spew useful info to dmesg. Good idea. I'm not sure if lockdep_assert is best fit but I will add something to check it rather than just adding the comment. Thanks. -- 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>