From patchwork Mon Jun 13 23:33:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Edward Liaw X-Patchwork-Id: 581483 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 375BFC433EF for ; Mon, 13 Jun 2022 23:33:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230256AbiFMXdx (ORCPT ); Mon, 13 Jun 2022 19:33:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229783AbiFMXdu (ORCPT ); Mon, 13 Jun 2022 19:33:50 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8098B3055D for ; Mon, 13 Jun 2022 16:33:49 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id 206-20020a6218d7000000b0051893ee2888so2943867pfy.16 for ; Mon, 13 Jun 2022 16:33:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=Lpl6bFxJI4CHRgZzmX1LV+v0qDroFLN/nvNicZhBWbk=; b=PBbqm2oEvfRdfqUL7Z30R+/pfa0TDaOZnOfFZ0FGkyyXTVfaeA859rqjWm5M1jgU4x x9JF9CHjapYA+Mh3kZOTZBfRwi95ukBYi4SdXiCXBziNv0P/HPw9E1dCWO6gbH+BcCKm tkhDkanIMftPysWbsqKlgR9QcfvPiyPBDZ/GSuklEWBnmW3oudZLo8ywT96P48LV6iA4 XmsVCsryoiDxhn+5j4mLRhSC2gJiFeyyEotYhoPswCKK6KwnReLTepOho7gwxE37W1Zi K/rIYy1sy8uQjBLmW9Eh+KI/HR8kZ34ztVrGSb3dFKCZ8WMgaXsxVEFfLfbbLSPqJGOj 6gTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=Lpl6bFxJI4CHRgZzmX1LV+v0qDroFLN/nvNicZhBWbk=; b=VqMYAZgz60dItlMX1ppV7jQrawYcTqC50Iy5ff4+Z+Re7xUASfOojMu74cv751YvES RLIcTlG61p2wDK+y+01jPcxTQs1A/yiPfX9/DOVFT3u+fUr0smaf70kGsniDF2Rdo3at pj9nCim0kUlBj2MlRPrJvmXiAwdQ0iZt4XnhqoKf7hX1JLYTkZ8Y9+1lexlx13X+5MeG iDJSM30hPJEw6/H965OkkWvJs2TVpMp8H/+T+Fd/VcwimUbsH9Yz0ZLCw40NfrVFNvWE 7I70FnD5esgVcg7+KCf8Vsso+S9QU1iRf84IsT2CtTsZAiBm4/64i58hPl5EwBzklKNs /dXA== X-Gm-Message-State: AJIora980SQZgxQ+6sRkvWsjpBieqYSL8B7GJyhmY1P7qESU3TZYu6BM 3oYkM1xFLTrH0IsNmy6VewsaiA5TlwY= X-Google-Smtp-Source: AGRyM1txbt+9NgJBywZye18wHMFrzrxDjzOEouzPoc8+gANuChnXlXGrxwM174nRDA4EmaMfxx9wSKZ3OXQ= X-Received: from edliaw.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:4be]) (user=edliaw job=sendgmr) by 2002:a17:90a:e7c8:b0:1e6:92fe:84c2 with SMTP id kb8-20020a17090ae7c800b001e692fe84c2mr1259645pjb.194.1655163228891; Mon, 13 Jun 2022 16:33:48 -0700 (PDT) Date: Mon, 13 Jun 2022 23:33:21 +0000 Message-Id: <20220613233321.431282-1-edliaw@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.36.1.476.g0c4daa206d-goog Subject: [PATCH v1] userfaultfd: selftests: infinite loop in faulting_process From: Edward Liaw To: shuah@kernel.org Cc: axelrasmussen@google.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@android.com, Edward Liaw Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Android this test is getting stuck in an infinite loop due to indeterminate behavior: The local variables steps and signalled were being reset to 1 and 0 respectively after every jump back to sigsetjmp by siglongjmp in the signal handler. The test was incrementing them and expecting them to retain their incremented values. The documentation for siglongjmp says: All accessible objects have values as of the time sigsetjmp() was called, except that the values of objects of automatic storage duration which are local to the function containing the invocation of the corresponding sigsetjmp() which do not have volatile-qualified type and which are changed between the sigsetjmp() invocation and siglongjmp() call are indeterminate. Tagging steps and signalled with volatile enabled the test to pass. Signed-off-by: Edward Liaw Reviewed-by: Axel Rasmussen --- tools/testing/selftests/vm/userfaultfd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 0bdfc1955229..2b2a68722ae1 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -931,7 +931,7 @@ static int faulting_process(int signal_test) unsigned long split_nr_pages; unsigned long lastnr; struct sigaction act; - unsigned long signalled = 0; + volatile unsigned long signalled = 0; split_nr_pages = (nr_pages + 1) / 2; @@ -946,7 +946,7 @@ static int faulting_process(int signal_test) } for (nr = 0; nr < split_nr_pages; nr++) { - int steps = 1; + volatile int steps = 1; unsigned long offset = nr * page_size; if (signal_test) {