On Fri, Nov 30, 2018 at 01:32:21PM -0700, Jens Axboe wrote: > On 11/30/18 1:15 PM, Jens Axboe wrote: > > On 11/30/18 12:21 PM, Al Viro wrote: > >> On Fri, Nov 30, 2018 at 09:56:43AM -0700, Jens Axboe wrote: > >>> For an ITER_KVEC, we can just iterate the iov and add the pages > >>> to the bio directly. > >> > >>> + page = virt_to_page(kv->iov_base); > >>> + size = bio_add_page(bio, page, kv->iov_len, > >>> + offset_in_page(kv->iov_base)); > >> > >> Who said that you *can* do virt_to_page() on those? E.g. vmalloc()'ed > >> addresses are fine for ITER_KVEC, etc. > > > > Then how do you set up a kvec based iter with memory you can safely > > DMA to/from? > > Would this make you happy: > > if (!is_vmalloc_addr(kv->iov_base)) > page = virt_to_page(kv->iov_base); > else > page = vmalloc_to_page(kv->iov_base); Free advice: don't ever let Linus see anything along those lines. Results tend to be colourful...
