On Mon, Feb 11, 2019 at 01:39:12PM -0800, John Hubbard wrote: > On 2/11/19 1:26 PM, Ira Weiny wrote: > > On Mon, Feb 11, 2019 at 01:13:56PM -0800, John Hubbard wrote: > >> On 2/11/19 12:39 PM, Jason Gunthorpe wrote: > >>> On Mon, Feb 11, 2019 at 12:16:42PM -0800, ira.weiny@xxxxxxxxx wrote: > >>>> From: Ira Weiny <ira.weiny@xxxxxxxxx> > >> [...] > >> It seems to me that the longterm vs. short-term is of questionable value. > > > > This is exactly why I did not post this before. I've been waiting our other > > discussions on how GUP pins are going to be handled to play out. But with the > > netdev thread today[1] it seems like we need to make sure we have a "safe" fast > > variant for a while. Introducing FOLL_LONGTERM seemed like the cleanest way to > > do that even if we will not need the distinction in the future... :-( > > Yes, I agree. Below... > > > [...] > > This is also why I did not change the get_user_pages_longterm because we could > > be ripping this all out by the end of the year... (I hope. :-) > > > > So while this does "pollute" the GUP family of calls I'm hoping it is not > > forever. > > > > Ira > > > > [1] https://lkml.org/lkml/2019/2/11/1789 > > > > Yes, and to be clear, I think your patchset here is fine. It is easy to find > the FOLL_LONGTERM callers if and when we want to change anything. I just think > also it's appopriate to go a bit further, and use FOLL_LONGTERM all by itself. > > That's because in either design outcome, it's better that way: > > -- If we keep the concept of "I'm a long-term gup call site", then FOLL_LONGTERM > is just right. The gup API already has _fast and non-fast variants, and once > you get past a couple, you end up with a multiplication of names that really > work better as flags. We're there. > > -- If we drop the concept, then you've already done part of the work, by removing > the _longterm API variants. Fair enough. But to do that correctly I think we will need to convert get_user_pages_fast() to use flags as well. I have a version of this series which includes a patch does this, but the patch touched a lot of subsystems and a couple of different architectures...[1] I can't test them all. If we want to go that way I'm up for submitting the patch... But if we remove longterm in the future we may be left with a get_user_pages_fast() which really only needs 1 flag. But perhaps overall we would be better off? Ira [1] mm/gup.c: Change GUP fast to use flags rather than write bool To facilitate additional options to get_user_pages_fast change the singular write parameter to be the more generic gup_flags. This patch currently does not change any functionality. New functionality will follow in subsequent patches. Many of the get_user_pages_fast call sites were unchanged because they already used FOLL_WRITE or 0 as appropriate. Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> --- arch/mips/mm/gup.c | 11 ++++++----- arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 ++-- arch/powerpc/kvm/e500_mmu.c | 2 +- arch/powerpc/mm/mmu_context_iommu.c | 4 ++-- arch/s390/kvm/interrupt.c | 2 +- arch/s390/mm/gup.c | 12 ++++++------ arch/sh/mm/gup.c | 11 ++++++----- arch/sparc/mm/gup.c | 9 +++++---- arch/x86/kvm/paging_tmpl.h | 2 +- arch/x86/kvm/svm.c | 2 +- drivers/fpga/dfl-afu-dma-region.c | 2 +- drivers/gpu/drm/via/via_dmablit.c | 3 ++- drivers/infiniband/hw/hfi1/user_pages.c | 3 ++- drivers/misc/genwqe/card_utils.c | 2 +- drivers/misc/vmw_vmci/vmci_host.c | 2 +- drivers/misc/vmw_vmci/vmci_queue_pair.c | 6 ++++-- drivers/platform/goldfish/goldfish_pipe.c | 3 ++- drivers/rapidio/devices/rio_mport_cdev.c | 4 +++- drivers/sbus/char/oradax.c | 2 +- drivers/scsi/st.c | 3 ++- drivers/staging/gasket/gasket_page_table.c | 4 ++-- drivers/tee/tee_shm.c | 2 +- drivers/vfio/vfio_iommu_spapr_tce.c | 3 ++- drivers/vhost/vhost.c | 2 +- drivers/video/fbdev/pvr2fb.c | 2 +- drivers/virt/fsl_hypervisor.c | 2 +- drivers/xen/gntdev.c | 2 +- fs/orangefs/orangefs-bufmap.c | 2 +- include/linux/mm.h | 4 ++-- kernel/futex.c | 2 +- lib/iov_iter.c | 7 +++++-- mm/gup.c | 10 +++++----- mm/util.c | 8 ++++---- net/ceph/pagevec.c | 2 +- net/rds/info.c | 2 +- net/rds/rdma.c | 3 ++- 36 files changed, 81 insertions(+), 65 deletions(-)
