On 10/11/2017 04:56 PM, Dave Chinner wrote: > On Wed, Oct 11, 2017 at 04:47:05PM -0400, Waiman Long wrote: >> On 10/10/2017 06:54 PM, Andrew Morton wrote: >>> On Mon, 18 Sep 2017 14:20:28 -0400 Waiman Long <longman@xxxxxxxxxx> wrote: >>> >>>> A rogue application can potentially create a large number of negative >>>> dentries in the system consuming most of the memory available even if >>>> memory controller is enabled to limit memory usage. This can impact >>>> performance of other applications running on the system. >>> It does seem that under these circumstances it is pretty silly of us to >>> reclaim useful things in order to instantiate zillions of -ve dentries. >> I am talking about a misbehaving program due to bug or an intentional >> rogue program. >> >>> Dentries are subject to kmemcg handling. Does this not help avoid >>> "impacting performance of other applications"? >> AFAIK, the dentry kmem_cache isn't memcg aware. > The dentry cache is most definitely is memcg aware. It (and teh > inode cache) were the primary targets for the memcg slab reclaim > infrastructure. > > #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) > # define SLAB_ACCOUNT 0x04000000UL /* Account to memcg */ > #else > # define SLAB_ACCOUNT 0x00000000UL > #endif > > dcache_init(): > > dentry_cache = KMEM_CACHE(dentry, > SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT); > Oh, my bad! You are right. However, it is still a problem for applications that are not being under any memcg. Cheers, Longman
