From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752461Ab2GHUcp (ORCPT ); Sun, 8 Jul 2012 16:32:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65084 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752408Ab2GHUcl (ORCPT ); Sun, 8 Jul 2012 16:32:41 -0400 Date: Sun, 8 Jul 2012 22:30:08 +0200 From: Oleg Nesterov To: Ingo Molnar , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: [PATCH 4/5] uprobes: kill copy_vma()->uprobe_mmap() Message-ID: <20120708203008.GA18236@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120708202917.GA18188@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kill copy_vma()->uprobe_mmap(new_vma), it is absolutely wrong. This new_vma was just initialized to represent the new unmapped area, [vm_start, vm_end) was returned by get_unmapped_area() in the caller. This means that uprobe_mmap()->get_user_pages() will fail for sure, simply because find_vma() can never succeed. And I verified that sys_mremap()->mremap_to() indeed always fails with the wrong ENOMEM code if [addr, addr+old_len] is probed. And why this uprobe_mmap() was added? I believe the intent was wrong. Note that the caller is going to do move_page_tables(), all registered uprobes are already faulted in, we only change the virtual addresses. NOTE: However, somehow we need to close the race with uprobe_register() which relies on map_info->vaddr. This needs another fix I'll try to do later. Probably we need uprobe_mmap() in move_vma() but we can not do this right now, this can confuse uprobes_state.counter (which I still hope we are going to kill). Signed-off-by: Oleg Nesterov --- mm/mmap.c | 3 --- 1 files changed, 0 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 3edfcdf..e5a4614 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2418,9 +2418,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, if (new_vma->vm_file) { get_file(new_vma->vm_file); - if (uprobe_mmap(new_vma)) - goto out_free_mempol; - if (vma->vm_flags & VM_EXECUTABLE) added_exe_file_vma(mm); } -- 1.5.5.1