On 11/10/2016 11:26 AM, Olaf Hering wrote: > On Tue, Nov 10, Boris Ostrovsky wrote:
Perfect timing. This is from Nov. 10 2015. > >> Doing so will cause the grant to be unmapped and then, during >> fault handling, the fault to be mistakenly treated as NUMA hint >> fault. >> >> In addition, even if those maps could partcipate in NUMA >> balancing, it wouldn't provide any benefit since we are unable >> to determine physical page's node (even if/when VNUMA is >> implemented). >> >> Marking grant maps' VMAs as VM_IO will exclude them from being >> part of NUMA balancing. > This breaks qdisk+aio because now such pages are rejected with -EFAULT: Is this something new? Because this patch has been there for a year. -boris > > check_vma_flags > __get_user_pages > __get_user_pages_locked > __get_user_pages_unlocked > get_user_pages_fast > iov_iter_get_pages > dio_refill_pages > do_direct_IO > do_blockdev_direct_IO > do_blockdev_direct_IO > ext4_direct_IO_read > generic_file_read_iter > aio_run_iocb > > domU.cfg: > builder=hvm > disk=['vdev=xvda, direct-io-safe, backendtype=qdisk, target=img.raw'] > >> @@ -802,7 +802,7 @@ static int gntdev_mmap(struct file *flip, struct >> vm_area_struct *vma) >> - vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; >> + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO; > > Olaf
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