From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2263u4kYhgzt0NRA5pABgBU5lap11QL6qaOXa9C4g3Sy2vVkgG3ePW9CRBU1CnOIaoUQprs2 ARC-Seal: i=1; a=rsa-sha256; t=1516983802; cv=none; d=google.com; s=arc-20160816; b=p7O//8HwpShKc73kmyLWatZIxQ1IC8iOdsh+f8OBP+CY4MH09ltQNcPRZpLIv7hr87 Wc8+Y+0A76f0aUy1OqqRGuJ/PdA9F2LlmGy9g3erYmnhbN1iiIB494+7I4698uIdNpnB weacDQDBnmkDEklPAs2fF3+pRK82haXor9Nzg3TnsMjr0Sj4swcCQJpmyoNIfSX6UB2K ma/BfXlmOOf9+4nX/Kj1QD2XFuIr4o2H1xJ7N1nXQ38hzQ5khK8VbtG6DUEZMK8dWMoG O+aJC9V4O/LOjUHW+1zoF8IZFG658KwmIvUQo0lPwwwu813olYwNAcfGDip3PD99BU1E 9fmA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:cc:to:subject:message-id:date:from :references:in-reply-to:mime-version:dmarc-filter :arc-authentication-results; bh=aGGuCkYOTTSdZAvqy6jVHslc3bS+UYulT4xhgLoFgOo=; b=AV+T0SZKi3zk7+4vMZVogfNdgW0ijkmNe2GgOwJI2ja/mmTrVYd6TjI2mDEqFw2jRo fiHUmOgQDPRi1x5kuk5+mD7XhwEK65r5R4n4gRvPJ8iJkktipeut0A8nqLPPIxjK9hJd TAdRf5ds4W850whysL3ACELu/YlVIgvyaiqRnR8FFKQm5P893s7dhLiEGhIvf7eZ8hkA IEM3Tuzbi+eH2XYKQnXr3YNRGjJ1erL0Rr1VARFQqB95kewTNtS2Mh7sYRqocPgTrYWV hfoxUPex2Xb/dX4vbib9zj6eHJ0rIVxtzsZmwjmDSQjslfRCj3ZNKlFH622ilZPTfZqt ZDGA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753692AbeAZQXK (ORCPT ); Fri, 26 Jan 2018 11:23:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:43980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751422AbeAZQXJ (ORCPT ); Fri, 26 Jan 2018 11:23:09 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B91A217D3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org MIME-Version: 1.0 In-Reply-To: <20180126153631.ha7yc33fj5uhitjo@xps> References: <20180126153631.ha7yc33fj5uhitjo@xps> From: Andy Lutomirski Date: Fri, 26 Jan 2018 08:22:48 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: selftests/x86/fsgsbase_64 test problem To: Dan Rue Cc: Shuah Khan , Ingo Molnar , Andy Lutomirski , Dmitry Safonov , Borislav Petkov , "open list:KERNEL SELFTEST FRAMEWORK" , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kselftest-owner@vger.kernel.org X-Mailing-List: linux-kselftest@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590669876861238825?= X-GMAIL-MSGID: =?utf-8?q?1590672808113499087?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Fri, Jan 26, 2018 at 7:36 AM, Dan Rue wrote: > > We've noticed that fsgsbase_64 can fail intermittently with the > following error: > > [RUN] ARCH_SET_GS(0x0) and clear gs, then schedule to 0x1 > Before schedule, set selector to 0x1 > other thread: ARCH_SET_GS(0x1) -- sel is 0x0 > [FAIL] GS/BASE changed from 0x1/0x0 to 0x0/0x0 > > This can be reliably reproduced by running fsgsbase_64 in a loop. i.e. > > for i in $(seq 1 10000); do ./fsgsbase_64 || break; done > > This problem isn't new - I've reproduced it on latest mainline and every > release going back to v4.12 (I did not try earlier). This was tested on > a Supermicro board with a Xeon E3-1220 as well as an Intel Nuc with an > i3-5010U. > Hmm, I can reproduce it, too. I'll look in a bit.