On Sat, Jun 15, 2019 at 07:17:26AM -0700, Christoph Hellwig wrote: > > - /* Sanity check this really should not happen. */ > > - if (hmm == NULL || range->end <= range->start) > > - return; > > - > > mutex_lock(&hmm->lock); > > list_del_rcu(&range->list); > > mutex_unlock(&hmm->lock); > > > > /* Drop reference taken by hmm_range_register() */ > > - range->valid = false; > > mmput(hmm->mm); > > hmm_put(hmm); > > - range->hmm = NULL; > > + > > + /* > > + * The range is now invalid and the ref on the hmm is dropped, so > > + * poison the pointer. Leave other fields in place, for the caller's > > + * use. > > + */ > > + range->valid = false; > > + memset(&range->hmm, POISON_INUSE, sizeof(range->hmm)); > > Formatting seems to be messed up. But again I don't see the value > in the poisoning, just let normal linked list debugging do its work. > The other cleanups looks fine to me. tabs vs spaces, I fixed it. This one is more murky than the other - it is to prevent the caller from using any of the range APIs after the range is unregistered, but we could also safely use NULL here, I think. Jason
