From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 8A3616B025E for ; Mon, 24 Oct 2016 07:15:34 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id z190so160748528qkc.4 for ; Mon, 24 Oct 2016 04:15:34 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id f123si10596545qkd.299.2016.10.24.04.15.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Oct 2016 04:15:33 -0700 (PDT) Subject: Re: [PATCH] mm: unexport __get_user_pages() References: <20161024095725.17229-1-lstoakes@gmail.com> From: Paolo Bonzini Message-ID: <329bad41-d1dc-d877-86be-452bbbfa5d01@redhat.com> Date: Mon, 24 Oct 2016 13:15:23 +0200 MIME-Version: 1.0 In-Reply-To: <20161024095725.17229-1-lstoakes@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Lorenzo Stoakes , linux-mm@kvack.org Cc: Linus Torvalds , Michal Hocko , Jan Kara , Hugh Dickins , Dave Hansen , Rik van Riel , Mel Gorman , Andrew Morton , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, linux-kernel@vger.kernel.org On 24/10/2016 11:57, Lorenzo Stoakes wrote: > This patch unexports the low-level __get_user_pages() function. Recent > refactoring of the get_user_pages* functions allow flags to be passed through > get_user_pages() which eliminates the need for access to this function from its > one user, kvm. > > We can see that the 2 calls to get_user_pages() which replace __get_user_pages() > in kvm_main.c are equivalent by examining their call stacks: > > get_user_page_nowait(): > get_user_pages(start, 1, flags, page, NULL) > __get_user_pages_locked(current, current->mm, start, 1, page, NULL, NULL, > false, flags | FOLL_TOUCH) > __get_user_pages(current, current->mm, start, 1, > flags | FOLL_TOUCH | FOLL_GET, page, NULL, NULL) > > check_user_page_hwpoison(): > get_user_pages(addr, 1, flags, NULL, NULL) > __get_user_pages_locked(current, current->mm, addr, 1, NULL, NULL, NULL, > false, flags | FOLL_TOUCH) > __get_user_pages(current, current->mm, addr, 1, flags | FOLL_TOUCH, NULL, > NULL, NULL) > > Signed-off-by: Lorenzo Stoakes > --- > include/linux/mm.h | 4 ---- > mm/gup.c | 3 +-- > mm/nommu.c | 2 +- > virt/kvm/kvm_main.c | 10 ++++------ > 4 files changed, 6 insertions(+), 13 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 3a19185..a92c8d7 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1271,10 +1271,6 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void * > extern int access_remote_vm(struct mm_struct *mm, unsigned long addr, > void *buf, int len, unsigned int gup_flags); > > -long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > - unsigned long start, unsigned long nr_pages, > - unsigned int foll_flags, struct page **pages, > - struct vm_area_struct **vmas, int *nonblocking); > long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > unsigned int gup_flags, struct page **pages, > diff --git a/mm/gup.c b/mm/gup.c > index 7aa113c..ec4f827 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -526,7 +526,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) > * instead of __get_user_pages. __get_user_pages should be used only if > * you need some special @gup_flags. > */ > -long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > +static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > unsigned int gup_flags, struct page **pages, > struct vm_area_struct **vmas, int *nonblocking) > @@ -631,7 +631,6 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > } while (nr_pages); > return i; > } > -EXPORT_SYMBOL(__get_user_pages); > > bool vma_permits_fault(struct vm_area_struct *vma, unsigned int fault_flags) > { > diff --git a/mm/nommu.c b/mm/nommu.c > index db5fd17..8b8faaf 100644 > --- a/mm/nommu.c > +++ b/mm/nommu.c > @@ -109,7 +109,7 @@ unsigned int kobjsize(const void *objp) > return PAGE_SIZE << compound_order(page); > } > > -long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > +static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > unsigned int foll_flags, struct page **pages, > struct vm_area_struct **vmas, int *nonblocking) > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 28510e7..2907b7b 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1346,21 +1346,19 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w > static int get_user_page_nowait(unsigned long start, int write, > struct page **page) > { > - int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET; > + int flags = FOLL_NOWAIT | FOLL_HWPOISON; > > if (write) > flags |= FOLL_WRITE; > > - return __get_user_pages(current, current->mm, start, 1, flags, page, > - NULL, NULL); > + return get_user_pages(start, 1, flags, page, NULL); > } > > static inline int check_user_page_hwpoison(unsigned long addr) > { > - int rc, flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_WRITE; > + int rc, flags = FOLL_HWPOISON | FOLL_WRITE; > > - rc = __get_user_pages(current, current->mm, addr, 1, > - flags, NULL, NULL, NULL); > + rc = get_user_pages(addr, 1, flags, NULL, NULL); > return rc == -EHWPOISON; > } > > Acked-by: Paolo Bonzini -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org