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 030E7C64EAD for ; Sun, 30 Sep 2018 07:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C558D2089D for ; Sun, 30 Sep 2018 07:43:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C558D2089D 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 S1728201AbeI3OPQ (ORCPT ); Sun, 30 Sep 2018 10:15:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49152 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727651AbeI3OPP (ORCPT ); Sun, 30 Sep 2018 10:15:15 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8D75FA70A; Sun, 30 Sep 2018 07:43:21 +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 470DD60164; Sun, 30 Sep 2018 07:43:17 +0000 (UTC) From: Peter Xu To: linux-kernel@vger.kernel.org Cc: Shuah Khan , Mike Kravetz , Mike Rapoport , Jerome Glisse , 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 v2 3/3] userfaultfd: selftest: recycle lock threads first Date: Sun, 30 Sep 2018 15:42:59 +0800 Message-Id: <20180930074259.18229-4-peterx@redhat.com> In-Reply-To: <20180930074259.18229-1-peterx@redhat.com> References: <20180930074259.18229-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Sun, 30 Sep 2018 07:43:21 +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. Acked-by: Mike Rapoport 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 7a8c6937cc67..5d1db824f73a 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -626,6 +626,12 @@ 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) { @@ -643,11 +649,6 @@ 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