On 18 July 2018 at 17:49, Shakeel Butt <shakeelb@xxxxxxxxxx> wrote: > On Wed, Jul 18, 2018 at 8:37 AM Bruce Merry <bmerry@xxxxxxxxx> wrote: >> That sounds promising. Is there any way to tell how many zombies there >> are, and is there any way to deliberately create zombies? If I can >> produce zombies that might give me a reliable way to reproduce the >> problem, which could then sensibly be tested against newer kernel >> versions. >> > > Yes, very easy to produce zombies, though I don't think kernel > provides any way to tell how many zombies exist on the system. > > To create a zombie, first create a memcg node, enter that memcg, > create a tmpfs file of few KiBs, exit the memcg and rmdir the memcg. > That memcg will be a zombie until you delete that tmpfs file. Thanks, that makes sense. I'll see if I can reproduce the issue. Do you expect the same thing to happen with normal (non-tmpfs) files that are sitting in the page cache, and/or dentries? Cheers Bruce -- Bruce Merry Senior Science Processing Developer SKA South Africa
