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 F2675C19F28 for ; Wed, 27 Jul 2022 17:43:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242935AbiG0Rn3 (ORCPT ); Wed, 27 Jul 2022 13:43:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242931AbiG0Rm5 (ORCPT ); Wed, 27 Jul 2022 13:42:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB77B62A50; Wed, 27 Jul 2022 09:52:21 -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 1C4E660D3B; Wed, 27 Jul 2022 16:52:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2475CC433C1; Wed, 27 Jul 2022 16:52:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658940739; bh=nuk6k46O1twf9CdjFjcfM3U4cWPkm33h0fNx0B0HY3c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oUAmARHiE9bYAMdfJx9fMrSoxKcWbCVw0wPEGVXigak0F7TJcSENQxepiwJSOmwdq sMNWmDvn1FyJfC9Q87dIjlkwjEPtppL0G9MK9HFLBTA+rRWHFWsZvi1PyJhU8urwV8 mmET15ioMflC3MnkWF/SNOs+PwjthNDXo4KnLDpU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Gavin Shan , Oliver Upton , Andrew Jones , Paolo Bonzini Subject: [PATCH 5.18 130/158] KVM: selftests: Fix target thread to be migrated in rseq_test Date: Wed, 27 Jul 2022 18:13:14 +0200 Message-Id: <20220727161026.610932328@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220727161021.428340041@linuxfoundation.org> References: <20220727161021.428340041@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Gavin Shan commit e923b0537d28e15c9d31ce8b38f810b325816903 upstream. In rseq_test, there are two threads, which are vCPU thread and migration worker separately. Unfortunately, the test has the wrong PID passed to sched_setaffinity() in the migration worker. It forces migration on the migration worker because zeroed PID represents the calling thread, which is the migration worker itself. It means the vCPU thread is never enforced to migration and it can migrate at any time, which eventually leads to failure as the following logs show. host# uname -r 5.19.0-rc6-gavin+ host# # cat /proc/cpuinfo | grep processor | tail -n 1 processor : 223 host# pwd /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm host# for i in `seq 1 100`; do \ echo "--------> $i"; ./rseq_test; done --------> 1 --------> 2 --------> 3 --------> 4 --------> 5 --------> 6 ==== Test Assertion Failure ==== rseq_test.c:265: rseq_cpu == cpu pid=3925 tid=3925 errno=4 - Interrupted system call 1 0x0000000000401963: main at rseq_test.c:265 (discriminator 2) 2 0x0000ffffb044affb: ?? ??:0 3 0x0000ffffb044b0c7: ?? ??:0 4 0x0000000000401a6f: _start at ??:? rseq CPU = 4, sched CPU = 27 Fix the issue by passing correct parameter, TID of the vCPU thread, to sched_setaffinity() in the migration worker. Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs") Suggested-by: Sean Christopherson Signed-off-by: Gavin Shan Reviewed-by: Oliver Upton Message-Id: <20220719020830.3479482-1-gshan@redhat.com> Reviewed-by: Andrew Jones Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- tools/testing/selftests/kvm/rseq_test.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -82,8 +82,9 @@ static int next_cpu(int cpu) return cpu; } -static void *migration_worker(void *ign) +static void *migration_worker(void *__rseq_tid) { + pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid; cpu_set_t allowed_mask; int r, i, cpu; @@ -106,7 +107,7 @@ static void *migration_worker(void *ign) * stable, i.e. while changing affinity is in-progress. */ smp_wmb(); - r = sched_setaffinity(0, sizeof(allowed_mask), &allowed_mask); + r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), &allowed_mask); TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)", errno, strerror(errno)); smp_wmb(); @@ -231,7 +232,8 @@ int main(int argc, char *argv[]) vm = vm_create_default(VCPU_ID, 0, guest_code); ucall_init(vm, NULL); - pthread_create(&migration_thread, NULL, migration_worker, 0); + pthread_create(&migration_thread, NULL, migration_worker, + (void *)(unsigned long)gettid()); for (i = 0; !done; i++) { vcpu_run(vm, VCPU_ID);