From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751414AbdAaQHy (ORCPT ); Tue, 31 Jan 2017 11:07:54 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47688 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751126AbdAaQHq (ORCPT ); Tue, 31 Jan 2017 11:07:46 -0500 Date: Tue, 31 Jan 2017 16:44:42 +0100 From: Oleg Nesterov To: "Kirill A. Shutemov" Cc: Andrea Arcangeli , Hugh Dickins , Rik van Riel , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCHv3 01/12] uprobes: split THPs before trying replace them Message-ID: <20170131154442.GA21637@redhat.com> References: <20170129173858.45174-1-kirill.shutemov@linux.intel.com> <20170129173858.45174-2-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170129173858.45174-2-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 31 Jan 2017 15:44:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/29, Kirill A. Shutemov wrote: > > For THPs page_check_address() always fails. It leads to endless loop in > uprobe_write_opcode(). > > Testcase with huge-tmpfs (not sure if it's possible to trigger this > uprobe codepath for anon memory): No, you can't probe the anonymous memory, > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -300,8 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, > > retry: > /* Read the page with vaddr into memory */ > - ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page, > - &vma, NULL); > + ret = get_user_pages_remote(NULL, mm, vaddr, 1, > + FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); > if (ret <= 0) > return ret; Thanks, Acked-by: Oleg Nesterov