On Fri, Apr 19, 2019 at 04:35:36PM -0700, rcampbell@xxxxxxxxxx wrote: > From: Ralph Campbell <rcampbell@xxxxxxxxxx> > > The mmotm patch [1] adds hugetlbfs support for HMM but the initial > PFN used to fill the HMM range->pfns[] array doesn't properly > compute the starting PFN offset. > This can be tested by running test-hugetlbfs-read from [2]. > > Fix the PFN offset by adjusting the page offset by the device's > page size. > > Andrew, this should probably be squashed into Jerome's patch. > > [1] https://marc.info/?l=linux-mm&m=155432003506068&w=2 > ("mm/hmm: mirror hugetlbfs (snapshoting, faulting and DMA mapping)") > [2] https://gitlab.freedesktop.org/glisse/svm-cl-tests > > Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Good catch. Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx> > Cc: Jérôme Glisse <jglisse@xxxxxxxxxx> > Cc: Ira Weiny <ira.weiny@xxxxxxxxx> > Cc: John Hubbard <jhubbard@xxxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > Cc: Balbir Singh <bsingharora@xxxxxxxxx> > Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > mm/hmm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/hmm.c b/mm/hmm.c > index def451a56c3e..fcf8e4fb5770 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -868,7 +868,7 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask, > goto unlock; > } > > - pfn = pte_pfn(entry) + (start & mask); > + pfn = pte_pfn(entry) + ((start & mask) >> range->page_shift); > for (; addr < end; addr += size, i++, pfn += pfn_inc) > range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) | > cpu_flags; > -- > 2.20.1 >
