From patchwork Sat Jul 16 14:45:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gavin Shan X-Patchwork-Id: 12920110 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 AC03AC43334 for ; Sat, 16 Jul 2022 12:46:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232014AbiGPMqU (ORCPT ); Sat, 16 Jul 2022 08:46:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229548AbiGPMqS (ORCPT ); Sat, 16 Jul 2022 08:46:18 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 09F5C1FCCA for ; Sat, 16 Jul 2022 05:46:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657975577; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=6jdgBr8qPyYQ7wIItqpQ8nbtb9ewBI0uvepqAzRBm0w=; b=iKRmnKrQ/8yPPNDKsbrVC/Mywnnz3IZfHIQuTpiWySU+saORem6mLA/ryqXmluMztYxEhn 9Sdn/4cuzC5QPA4e+r9VOs7yCxAvVdM3RbDaCqdZ7L7sPTL0advkL/AwAFT2XPJy+NW18n suv8n4oW1zT41xFrw2y23UW+VtBLeW4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-649-jVl0NklINweQDDm3TzrjdQ-1; Sat, 16 Jul 2022 08:46:15 -0400 X-MC-Unique: jVl0NklINweQDDm3TzrjdQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A4A358037B7; Sat, 16 Jul 2022 12:46:14 +0000 (UTC) Received: from gshan.redhat.com (vpn2-54-37.bne.redhat.com [10.64.54.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ED01E492C3B; Sat, 16 Jul 2022 12:46:10 +0000 (UTC) From: Gavin Shan To: kvmarm@lists.cs.columbia.edu Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, seanjc@google.com, pbonzini@redhat.com, maz@kernel.org, shuah@kernel.org, oliver.upton@linux.dev, shan.gavin@gmail.com Subject: [PATCH v2] KVM: selftests: Fix target thread to be migrated in rseq_test Date: Sat, 16 Jul 2022 22:45:37 +0800 Message-Id: <20220716144537.3436743-1-gshan@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org In rseq_test, there are two threads, which are thread group leader and migration worker. The migration worker relies on sched_setaffinity() to force migration on the thread group leader. Unfortunately, we have wrong parameter (0) passed to sched_getaffinity(). It's actually forcing migration on the migration worker instead of the thread group leader. It also means migration can happen on the thread group leader 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 This fixes the issue by passing correct parameter, tid of the group thread leader, to sched_setaffinity(). Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs") Signed-off-by: Gavin Shan Reviewed-by: Oliver Upton --- tools/testing/selftests/kvm/rseq_test.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c index 4158da0da2bb..c83ac7b467f8 100644 --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -38,6 +38,7 @@ static __thread volatile struct rseq __rseq = { */ #define NR_TASK_MIGRATIONS 100000 +static pid_t rseq_tid; static pthread_t migration_thread; static cpu_set_t possible_mask; static int min_cpu, max_cpu; @@ -106,7 +107,8 @@ 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(); @@ -231,6 +233,7 @@ int main(int argc, char *argv[]) vm = vm_create_default(VCPU_ID, 0, guest_code); ucall_init(vm, NULL); + rseq_tid = gettid(); pthread_create(&migration_thread, NULL, migration_worker, 0); for (i = 0; !done; i++) {