On Fri, Jul 06, 2018 at 04:00:30PM +1000, Michael Ellerman wrote: > Alexey Kardashevskiy <aik@xxxxxxxxx> writes: > > > diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c > > index abb4364..11e1029 100644 > > --- a/arch/powerpc/mm/mmu_context_iommu.c > > +++ b/arch/powerpc/mm/mmu_context_iommu.c > > @@ -159,6 +161,7 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries, > > goto unlock_exit; > > } > > > > + mem->pageshift = __builtin_ctzl(ua | (entries << PAGE_SHIFT)); > > __builtin_ctzl(0) is undefined, so are we guaranteed that > (ua | (entries << PAGE_SHIFT)) is never zero? I couldn't convince > myself. We certainly don't need to care about that case, since registering a zero-length region (entries == 0) is no-op. But maybe we need to filter it above. > > @@ -199,9 +202,17 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries, > > } > > } > > populate: > > + pageshift = PAGE_SHIFT; > > + if (PageCompound(page)) > > + pageshift += compound_order(compound_head(page)); > > + mem->pageshift = min(mem->pageshift, pageshift); > > mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT; > > } > > > > + /* We have an incomplete huge page, default to PAGE_SHIFT */ > > + if (head) > > + mem->pageshift = PAGE_SHIFT; > > + > > You never set head AFIACS? (other than in the initialiser) That looks like a leftover from the previous version. > > cheers > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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