From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:36582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732139AbeLNMQY (ORCPT ); Fri, 14 Dec 2018 07:16:24 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lorenzo Stoakes , Paolo Bonzini , Jan Kara , Michal Hocko , Linus Torvalds , Ben Hutchings Subject: [PATCH 4.4 75/88] mm: remove write/force parameters from __get_user_pages_unlocked() Date: Fri, 14 Dec 2018 13:00:49 +0100 Message-Id: <20181214115708.360510296@linuxfoundation.org> In-Reply-To: <20181214115702.151309521@linuxfoundation.org> References: <20181214115702.151309521@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lorenzo Stoakes commit d4944b0ecec0af882483fe44b66729316e575208 upstream. This removes the redundant 'write' and 'force' parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by: Lorenzo Stoakes Acked-by: Paolo Bonzini Reviewed-by: Jan Kara Acked-by: Michal Hocko Signed-off-by: Linus Torvalds [bwh: Backported to 4.4: - Defer changes in process_vm_rw_single_vec() and async_pf_execute() since they use get_user_pages_unlocked() here - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/linux/mm.h | 3 +-- mm/gup.c | 19 ++++++++++--------- mm/nommu.c | 14 ++++++++++---- virt/kvm/kvm_main.c | 11 ++++++++--- 4 files changed, 29 insertions(+), 18 deletions(-) --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1207,8 +1207,7 @@ long get_user_pages_locked(struct task_s int *locked); long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags); + struct page **pages, unsigned int gup_flags); long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages); --- a/mm/gup.c +++ b/mm/gup.c @@ -764,17 +764,11 @@ EXPORT_SYMBOL(get_user_pages_locked); */ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags) + struct page **pages, unsigned int gup_flags) { long ret; int locked = 1; - if (write) - gup_flags |= FOLL_WRITE; - if (force) - gup_flags |= FOLL_FORCE; - down_read(&mm->mmap_sem); ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL, &locked, false, gup_flags); @@ -805,8 +799,15 @@ long get_user_pages_unlocked(struct task unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { - return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write, - force, pages, FOLL_TOUCH); + unsigned int flags = FOLL_TOUCH; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + + return __get_user_pages_unlocked(tsk, mm, start, nr_pages, + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked); --- a/mm/nommu.c +++ b/mm/nommu.c @@ -211,8 +211,7 @@ EXPORT_SYMBOL(get_user_pages_locked); long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, - int write, int force, struct page **pages, - unsigned int gup_flags) + struct page **pages, unsigned int gup_flags) { long ret; down_read(&mm->mmap_sem); @@ -227,8 +226,15 @@ long get_user_pages_unlocked(struct task unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages) { - return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write, - force, pages, 0); + unsigned int flags = 0; + + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + + return __get_user_pages_unlocked(tsk, mm, start, nr_pages, + pages, flags); } EXPORT_SYMBOL(get_user_pages_unlocked); --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1352,10 +1352,15 @@ static int hva_to_pfn_slow(unsigned long npages = get_user_page_nowait(current, current->mm, addr, write_fault, page); up_read(¤t->mm->mmap_sem); - } else + } else { + unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON; + + if (write_fault) + flags |= FOLL_WRITE; + npages = __get_user_pages_unlocked(current, current->mm, addr, 1, - write_fault, 0, page, - FOLL_TOUCH|FOLL_HWPOISON); + page, flags); + } if (npages != 1) return npages;