From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.4 required=3.0 tests=DATE_IN_PAST_06_12, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34F0AC4360F for ; Mon, 25 Mar 2019 16:27:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 04A3B20828 for ; Mon, 25 Mar 2019 16:27:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729669AbfCYQ1e (ORCPT ); Mon, 25 Mar 2019 12:27:34 -0400 Received: from mga18.intel.com ([134.134.136.126]:50097 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725788AbfCYQ1e (ORCPT ); Mon, 25 Mar 2019 12:27:34 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Mar 2019 09:27:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,269,1549958400"; d="scan'208";a="217406487" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga001.jf.intel.com with ESMTP; 25 Mar 2019 09:27:31 -0700 Date: Mon, 25 Mar 2019 01:26:20 -0700 From: Ira Weiny To: Dan Williams Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , linux-mm , Linux Kernel Mailing List , linux-mips@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, "netdev@vger.kernel.org" Subject: Re: [RESEND 3/7] mm/gup: Change GUP fast to use flags rather than a write 'bool' Message-ID: <20190325082620.GB16366@iweiny-DESK2.sc.intel.com> References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-4-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 22, 2019 at 03:05:53PM -0700, Dan Williams wrote: > On Sun, Mar 17, 2019 at 7:36 PM wrote: > > > > From: Ira Weiny > > > > To facilitate additional options to get_user_pages_fast() change the > > singular write parameter to be gup_flags. > > > > This patch does not change any functionality. New functionality will > > follow in subsequent patches. > > > > Some of the get_user_pages_fast() call sites were unchanged because they > > already passed FOLL_WRITE or 0 for the write parameter. > > > > Signed-off-by: Ira Weiny > > > > --- > > Changes from V1: > > Rebase to current merge tree > > arch/powerpc/mm/mmu_context_iommu.c no longer calls gup_fast > > The gup_longterm was converted in patch 1 > > > > arch/mips/mm/gup.c | 11 ++++++----- > > arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 ++-- > > arch/powerpc/kvm/e500_mmu.c | 2 +- > > 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 ++- > > 35 files changed, 79 insertions(+), 63 deletions(-) > > > > > > diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c > > index 0d14e0d8eacf..4c2b4483683c 100644 > > --- a/arch/mips/mm/gup.c > > +++ b/arch/mips/mm/gup.c > > @@ -235,7 +235,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > > * get_user_pages_fast() - pin user pages in memory > > * @start: starting user address > > * @nr_pages: number of pages from start to pin > > - * @write: whether pages will be written to > > + * @gup_flags: flags modifying pin behaviour > > * @pages: array that receives pointers to the pages pinned. > > * Should be at least nr_pages long. > > * > > @@ -247,8 +247,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > > * requested. If nr_pages is 0 or negative, returns 0. If no pages > > * were pinned, returns -errno. > > */ > > -int get_user_pages_fast(unsigned long start, int nr_pages, int write, > > - struct page **pages) > > +int get_user_pages_fast(unsigned long start, int nr_pages, > > + unsigned int gup_flags, struct page **pages) > > This looks a tad scary given all related thrash especially when it's > only 1 user that wants to do get_user_page_fast_longterm, right? Agreed but the discussion back in Feb agreed that it would be better to make get_user_pages_fast() use flags rather than add another *_longterm call, and I agree. > Maybe > something like the following. Note I explicitly moved the flags to the > end so that someone half paying attention that calls > __get_user_pages_fast will get a compile error if they specify the > args in the same order. I did this to remain consistent with the other public calls. They put the "return" pages parameter at the end. For example get_user_pages() is defined this way with pages and vmas at the end. long get_user_pages(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, struct vm_area_struct **vmas) I'm pretty sure I got all the callers. Is this worth making the signature "non-standard" WRT the other calls? Ira > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 76ba638ceda8..c6c743bc2c68 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1505,8 +1505,15 @@ static inline long > get_user_pages_longterm(unsigned long start, > } > #endif /* CONFIG_FS_DAX */ > > -int get_user_pages_fast(unsigned long start, int nr_pages, int write, > - struct page **pages); > + > +int __get_user_pages_fast(unsigned long start, int nr_pages, > + struct page **pages, unsigned int gup_flags); > + > +static inline int get_user_pages_fast(unsigned long start, int > nr_pages, int write, > + struct page **pages) > +{ > + return __get_user_pages_fast(start, nr_pages, pages, write ? > FOLL_WRITE); > +} > > /* Container for pinned pfns / pages */ > struct frame_vector { >