On Mon, May 06, 2019 at 04:29:39PM -0700, rcampbell@xxxxxxxxxx wrote: > @@ -924,6 +922,7 @@ int hmm_range_register(struct hmm_range *range, > unsigned page_shift) > { > unsigned long mask = ((1UL << page_shift) - 1UL); > + struct hmm *hmm; > > range->valid = false; > range->hmm = NULL; I was finishing these patches off and noticed that 'hmm' above is never initialized. I added the below to this patch: diff --git a/mm/hmm.c b/mm/hmm.c index 678873eb21930a..8e7403f081f44a 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -932,19 +932,20 @@ int hmm_range_register(struct hmm_range *range, range->start = start; range->end = end; - range->hmm = hmm_get_or_create(mm); - if (!range->hmm) + hmm = hmm_get_or_create(mm); + if (!hmm) return -EFAULT; /* Check if hmm_mm_destroy() was call. */ - if (range->hmm->mm == NULL || range->hmm->dead) { - hmm_put(range->hmm); + if (hmm->mm == NULL || hmm->dead) { + hmm_put(hmm); return -EFAULT; } /* Initialize range to track CPU page table updates. */ - mutex_lock(&range->hmm->lock); + mutex_lock(&hmm->lock); + range->hmm = hmm; list_add_rcu(&range->list, &hmm->ranges); /* Which I think was the intent of adding the 'struct hmm *'. I prefer this arrangement as it does not set an leave an invalid hmm pointer in the range if there is a failure.. Most probably the later patches fixed this up? Please confirm, thanks Regards, Jason