On Fri, Nov 24, 2017 at 12:04:23AM +0900, Tetsuo Handa wrote: > Al Viro wrote: > > On Thu, Nov 23, 2017 at 03:35:37PM +0100, Michal Hocko wrote: > > > Hopefully less screwed version. But as I've said I am not really > > > familiar with the code and do not feel competent to change it so please > > > be very careful here. I've moved the shrinker registration to > > > alloc_super which turned out to be simpler. > > > > I don't get it. Why the hell do we need all that PITA in the first place? > > Just make sget_userns() end with > > if (unlikely(regsiter_shrinker(&s->s_shrink) != 0)) { > > deactivate_locked_super(s); > > s = ERR_PTR(-ENOMEM); > > } > > return s; > > and be done with that. All there is to it... > > > > Doesn't deactivate_locked_super() call unregister_shrinker() ? And? unregister_shrinker() will do list_del() on empty list_head and kfree(NULL); where's the problem with that?