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 X-Spam-Level: X-Spam-Status: No, score=-5.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E2F2C4363D for ; Fri, 25 Sep 2020 07:32:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DED0023600 for ; Fri, 25 Sep 2020 07:32:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="h6C/9OX8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727392AbgIYHcG (ORCPT ); Fri, 25 Sep 2020 03:32:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20417 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727238AbgIYHcG (ORCPT ); Fri, 25 Sep 2020 03:32:06 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601019125; 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: in-reply-to:in-reply-to:references:references; bh=OAW0t8KRUC4c7xqD0bS+SqinnFap8rpYlqZ1QIeslGs=; b=h6C/9OX81qxbSAfqnzqgaqeUhELpLdUW5jAM7xpycRySgOLULe0Jf2wTqJJgKdBzrzTsU6 yQypINw0WPVGM4pp5JtpqyXPLUfz3c/6A/cEPE5NXicD9FZtX949KUBl5UJiO5Wmpazg1Y npJTOcvjsd4Ljqq78stq+2M94iUhwZc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-259-f8TCAxi5Ni-7JRU_QYwxdg-1; Fri, 25 Sep 2020 03:32:00 -0400 X-MC-Unique: f8TCAxi5Ni-7JRU_QYwxdg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A47B11DE1B; Fri, 25 Sep 2020 07:31:58 +0000 (UTC) Received: from T590 (ovpn-12-168.pek2.redhat.com [10.72.12.168]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D1E4B1A918; Fri, 25 Sep 2020 07:31:49 +0000 (UTC) Date: Fri, 25 Sep 2020 15:31:45 +0800 From: Ming Lei To: "Theodore Y. Ts'o" Cc: Jens Axboe , linux-ext4@vger.kernel.org, "linux-kernel@vger.kernel.org" , linux-block@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org Subject: Re: REGRESSION: 37f4a24c2469: blk-mq: centralise related handling into blk_mq_get_driver_tag Message-ID: <20200925073145.GC2388140@T590> References: <20200915044519.GA38283@mit.edu> <20200915073303.GA754106@T590> <20200915224541.GB38283@mit.edu> <20200915230941.GA791425@T590> <20200916202026.GC38283@mit.edu> <20200917022051.GA1004828@T590> <20200917143012.GF38283@mit.edu> <20200924005901.GB1806978@T590> <20200924143345.GD482521@mit.edu> <20200925011311.GJ482521@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200925011311.GJ482521@mit.edu> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Sep 24, 2020 at 09:13:11PM -0400, Theodore Y. Ts'o wrote: > On Thu, Sep 24, 2020 at 10:33:45AM -0400, Theodore Y. Ts'o wrote: > > HOWEVER, thanks to a hint from a colleague at $WORK, and realizing > > that one of the stack traces had virtio balloon in the trace, I > > realized that when I switched the GCE VM type from e1-standard-2 to > > n1-standard-2 (where e1 VM's are cheaper because they use > > virtio-balloon to better manage host OS memory utilization), problem > > has become, much, *much* rarer (and possibly has gone away, although > > I'm going to want to run a lot more tests before I say that > > conclusively) on my test setup. At the very least, using an n1 VM > > (which doesn't have virtio-balloon enabled in the hypervisor) is > > enough to unblock ext4 development. > > .... and I spoke too soon. A number of runs using -rc6 are now > failing even with the n1-standard-2 VM, so virtio-ballon may not be an > indicator. > > This is why debugging this is frustrating; it is very much a heisenbug > --- although 5.8 seems to work completely reliably, as does commits > before 37f4a24c2469. Anything after that point will show random > failures. :-( It does not make sense to mention 37f4a24c2469, which is reverted in 4e2f62e566b5. Later the patch in 37f4a24c2469 is fixed and re-commited as 568f27006577. However, I can _not_ reproduce the issue by running the same test on kernel built from 568f27006577 directly. Also you have confirmed that the issue can't be fixed after reverting 568f27006577 against v5.9-rc4. Looks the real issue(slab list corruption) should be introduced between 568f27006577 and v5.9-rc4. thanks, Ming