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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57BD0C433EF for ; Tue, 14 Jun 2022 18:01:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237431AbiFNSBQ (ORCPT ); Tue, 14 Jun 2022 14:01:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232199AbiFNSBP (ORCPT ); Tue, 14 Jun 2022 14:01:15 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 360BC2A273 for ; Tue, 14 Jun 2022 11:01:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C1B3F6175D for ; Tue, 14 Jun 2022 18:01:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A8C7C3411B; Tue, 14 Jun 2022 18:01:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1655229673; bh=asjedtuFgjhkBpp9oLNmA1ktINxDKfzUETqpUGLT+1s=; h=Date:To:From:Subject:From; b=Rpq1IT6ObGn0UU+UErAbLHVWHs+EWhxRK3hv50r1WIOZdZ/rVOIcjRfjrcKIZQeJ9 2myNE67jktjn9bTDQjyG6cuvibODsAh+F+sYQYHJiRvlxmE0MLNp3qyThz+rCWCNik 9qKVqTyuSv8xYtFQDf4Ky6TE4ru+u1HBVbhx4aS0= Date: Tue, 14 Jun 2022 11:01:12 -0700 To: mm-commits@vger.kernel.org, shuah@kernel.org, peterx@redhat.com, axelrasmussen@google.com, edliaw@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: + userfaultfd-selftests-infinite-loop-in-faulting_process.patch added to mm-unstable branch Message-Id: <20220614180113.1A8C7C3411B@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: userfaultfd: selftests: infinite loop in faulting_process has been added to the -mm mm-unstable branch. Its filename is userfaultfd-selftests-infinite-loop-in-faulting_process.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/userfaultfd-selftests-infinite-loop-in-faulting_process.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Edward Liaw Subject: userfaultfd: selftests: infinite loop in faulting_process Date: Mon, 13 Jun 2022 23:33:21 +0000 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. Link: https://lkml.kernel.org/r/20220613233321.431282-1-edliaw@google.com Signed-off-by: Edward Liaw Cc: Shuah Khan Cc: Axel Rasmussen Cc: Peter Xu Signed-off-by: Andrew Morton --- tools/testing/selftests/vm/userfaultfd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftests-infinite-loop-in-faulting_process +++ a/tools/testing/selftests/vm/userfaultfd.c @@ -963,7 +963,7 @@ static int faulting_process(int signal_t 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; @@ -978,7 +978,7 @@ static int faulting_process(int signal_t } for (nr = 0; nr < split_nr_pages; nr++) { - int steps = 1; + volatile int steps = 1; unsigned long offset = nr * page_size; if (signal_test) { _ Patches currently in -mm which might be from edliaw@google.com are userfaultfd-selftests-infinite-loop-in-faulting_process.patch