Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751458AbdGZTCm (ORCPT ); Wed, 26 Jul 2017 15:02:42 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:45551 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750930AbdGZTCk (ORCPT ); Wed, 26 Jul 2017 15:02:40 -0400 Subject: Re: [RESEND PATCH 2/2] userfaultfd: selftest: Add tests for UFFD_FREATURE_SIGBUS To: Andrea Arcangeli References: <1500958062-953846-1-git-send-email-prakash.sangappa@oracle.com> <1500958062-953846-3-git-send-email-prakash.sangappa@oracle.com> <20170726142723.GW29716@redhat.com> Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, rppt@linux.vnet.ibm.com, akpm@linux-foundation.org, mike.kravetz@oracle.com From: Prakash Sangappa Message-ID: Date: Wed, 26 Jul 2017 12:02:31 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170726142723.GW29716@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1542 Lines: 43 On 7/26/17 7:27 AM, Andrea Arcangeli wrote: > On Tue, Jul 25, 2017 at 12:47:42AM -0400, Prakash Sangappa wrote: >> Signed-off-by: Prakash Sangappa >> --- >> tools/testing/selftests/vm/userfaultfd.c | 121 +++++++++++++++++++++++++++++- >> 1 files changed, 118 insertions(+), 3 deletions(-) > Like Mike said, some comment about the test would be better, commit > messages are never one liners in the kernel. Ok > >> @@ -408,6 +409,7 @@ static int copy_page(int ufd, unsigned long offset) >> userfaults++; >> break; >> case UFFD_EVENT_FORK: >> + close(uffd); >> uffd = msg.arg.fork.ufd; >> pollfd[0].fd = uffd; >> break; > Isn't this fd leak bugfix independent of the rest of the changes? The > only side effects should have been that it could run out of fds, but I > assume this was found by source review as I doubt it could run out of fds. > This could be splitted off in a separate patch. Not just the fd leak, it causes problems here with the addition of the new test userfaultfd_sig_test(). Since the original vma registration persists in the parent, subsequent registration in userfaultfd_events_test() fails with 'EBUSY' error, as userfault implementation does not allow registering same vma with another uffd, while one exists. Therefore, will need this change. I could just leave this fix here along with the rest of the changes, will that be ok? -Prakash > Overall it looks a good test also exercising UFFD_EVENT_FORK at the > same time. > > Thanks, > Andrea