From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D123C43143 for ; Sat, 29 Sep 2018 08:43:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46CA220895 for ; Sat, 29 Sep 2018 08:43:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46CA220895 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727947AbeI2PLK (ORCPT ); Sat, 29 Sep 2018 11:11:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37066 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727637AbeI2PLJ (ORCPT ); Sat, 29 Sep 2018 11:11:09 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 203D688306; Sat, 29 Sep 2018 08:43:34 +0000 (UTC) Received: from xz-x1.nay.redhat.com (dhcp-14-128.nay.redhat.com [10.66.14.128]) by smtp.corp.redhat.com (Postfix) with ESMTP id C5694106A790; Sat, 29 Sep 2018 08:43:29 +0000 (UTC) From: Peter Xu To: linux-kernel@vger.kernel.org Cc: Shuah Khan , Jerome Glisse , Mike Rapoport , Mike Kravetz , peterx@redhat.com, linux-mm@kvack.org, Zi Yan , "Kirill A . Shutemov" , linux-kselftest@vger.kernel.org, Shaohua Li , Andrea Arcangeli , "Dr . David Alan Gilbert" , Andrew Morton Subject: [PATCH 3/3] userfaultfd: selftest: recycle lock threads first Date: Sat, 29 Sep 2018 16:43:11 +0800 Message-Id: <20180929084311.15600-4-peterx@redhat.com> In-Reply-To: <20180929084311.15600-1-peterx@redhat.com> References: <20180929084311.15600-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Sat, 29 Sep 2018 08:43:34 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now we recycle the uffd servicing threads earlier than the lock threads. It might happen that when the lock thread is still blocked at a pthread mutex lock while the servicing thread has already quitted for the cpu so the lock thread will be blocked forever and hang the test program. To fix the possible race, recycle the lock threads first. This never happens with current missing-only tests, but when I start to run the write-protection tests (the feature is not yet posted upstream) it happens every time of the run possibly because in that new test we'll need to service two page faults for each lock operation. Signed-off-by: Peter Xu --- tools/testing/selftests/vm/userfaultfd.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index f79706f13ce7..a388675b15af 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -623,6 +623,12 @@ static int stress(unsigned long *userfaults) if (uffd_test_ops->release_pages(area_src)) return 1; + + finished = 1; + for (cpu = 0; cpu < nr_cpus; cpu++) + if (pthread_join(locking_threads[cpu], NULL)) + return 1; + for (cpu = 0; cpu < nr_cpus; cpu++) { char c; if (bounces & BOUNCE_POLL) { @@ -640,11 +646,6 @@ static int stress(unsigned long *userfaults) } } - finished = 1; - for (cpu = 0; cpu < nr_cpus; cpu++) - if (pthread_join(locking_threads[cpu], NULL)) - return 1; - return 0; } -- 2.17.1