From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753227AbbKQDqT (ORCPT ); Mon, 16 Nov 2015 22:46:19 -0500 Received: from mga02.intel.com ([134.134.136.20]:63319 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752095AbbKQDfO (ORCPT ); Mon, 16 Nov 2015 22:35:14 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,305,1444719600"; d="scan'208";a="821807556" Subject: [PATCH 02/37] mm, frame_vector: do not use get_user_pages_locked() To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Dave Hansen , dave.hansen@linux.intel.com, jack@suse.cz, akpm@linux-foundation.org, aarcange@redhat.com From: Dave Hansen Date: Mon, 16 Nov 2015 19:35:14 -0800 References: <20151117033511.BFFA1440@viggo.jf.intel.com> In-Reply-To: <20151117033511.BFFA1440@viggo.jf.intel.com> Message-Id: <20151117033514.B104D3A2@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen get_user_pages_locked() appears to be for use when a caller needs to know that its lock on mmap_sem was invalidated by the gup call. But, get_vaddr_frames() is not one of those users. It unconditionally locks the mmap_sem and unconditionally unlocks it after the gup call. It takes no special action and does not need to know whether its lock was invalidated or not. Replace get_user_pages_locked() with a vanilla get_user_pages() and save a few lines of code. Note that this was the *ONLY* use of get_user_pages_locked() in the entire kernel tree. Signed-off-by: Dave Hansen Cc: Jan Kara Cc: Andrew Morton Cc: Andrea Arcangeli --- b/mm/frame_vector.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff -puN mm/frame_vector.c~remove-get_user_pages_locked-user mm/frame_vector.c --- a/mm/frame_vector.c~remove-get_user_pages_locked-user 2015-11-16 12:35:35.282169293 -0800 +++ b/mm/frame_vector.c 2015-11-16 12:35:35.285169429 -0800 @@ -40,7 +40,6 @@ int get_vaddr_frames(unsigned long start struct vm_area_struct *vma; int ret = 0; int err; - int locked; if (nr_frames == 0) return 0; @@ -49,7 +48,6 @@ int get_vaddr_frames(unsigned long start nr_frames = vec->nr_allocated; down_read(&mm->mmap_sem); - locked = 1; vma = find_vma_intersection(mm, start, start + 1); if (!vma) { ret = -EFAULT; @@ -58,8 +56,8 @@ int get_vaddr_frames(unsigned long start if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false; - ret = get_user_pages_locked(current, mm, start, nr_frames, - write, force, (struct page **)(vec->ptrs), &locked); + ret = get_user_pages(current, mm, start, nr_frames, + write, force, (struct page **)(vec->ptrs), NULL); goto out; } @@ -87,8 +85,7 @@ int get_vaddr_frames(unsigned long start vma = find_vma_intersection(mm, start, start + 1); } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP)); out: - if (locked) - up_read(&mm->mmap_sem); + up_read(&mm->mmap_sem); if (!ret) ret = -EFAULT; if (ret > 0) _