Alexander Graf <agraf@xxxxxxx> writes: > On 13.06.14 16:28, Aneesh Kumar K.V wrote: >> Alexander Graf <agraf@xxxxxxx> writes: >> >>> On 13.06.14 09:23, Aneesh Kumar K.V wrote: >>>> With guest supporting Multiple page size per segment (MPSS), >>>> hpte_page_size returns actual page size used. Add a new function to >>>> return base page size and use that to compare against the the page size >>>> calculated from SLB >>> Why? What does this fix? Is this a bug fix, an enhancement? Don't >>> describe only what you do, but also why you do it. >>> >>> >> This could result in page fault failures (unhandled page fault) because >> even though we have a valid hpte entry mapping a 16MB page, since we >> were comparing actual page size against page size calculated from SLB >> bits kvmppc_hv_find_lock_hpte will fail and return -1. I did not observe >> a failure in real and the bug was found during code audit. That could be >> because with THP we have guest ram backed by hugetlbfs and we always >> find the page in the host linux page table. The will result in do_h_enter always >> inserting HPTE_V_VALID entry and hence we might not really end up calling >> kvmppc_hv_find_lock_hpte. > > So why do we need to override to base page size for the VRMA region? slb encoding should be derived based on base page size. > Also I think you want to change the comment above the line in > find_lock_hpte you're changing. > Will do that. -aneesh -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
