From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 5F4216B0253 for ; Thu, 21 Dec 2017 19:29:34 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id k1so16632735pgq.2 for ; Thu, 21 Dec 2017 16:29:34 -0800 (PST) Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com. [66.63.167.143]) by mx.google.com with ESMTPS id g64si5217247pgc.762.2017.12.21.16.29.33 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Dec 2017 16:29:33 -0800 (PST) Message-ID: <1513902570.3132.22.camel@HansenPartnership.com> Subject: Re: Regression with a0747a859ef6 ("bdi: add error handle for bdi_debug_register") From: James Bottomley Date: Thu, 21 Dec 2017 16:29:30 -0800 In-Reply-To: <14f04d43-728a-953f-e07c-e7f9d5e3392d@kernel.dk> References: <20171221130057.GA26743@wolff.to> <20171221151843.GA453@wolff.to> <20171221153631.GA2300@wolff.to> <20171221164221.GA23680@wolff.to> <14f04d43-728a-953f-e07c-e7f9d5e3392d@kernel.dk> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Jens Axboe , Bruno Wolff III , weiping zhang Cc: Laura Abbott , Jan Kara , linux-mm@kvack.org, Linux Kernel Mailing List , regressions@leemhuis.info, weiping zhang , linux-block@vger.kernel.org On Thu, 2017-12-21 at 10:02 -0700, Jens Axboe wrote: > On 12/21/17 9:42 AM, Bruno Wolff III wrote: > > > > On Thu, Dec 21, 2017 at 23:48:19 +0800, > > A weiping zhang wrote: > > > > > > > > > > > output you want. I never saw it for any kernels I compiled > > > > myself. Only when I test kernels built by Fedora do I see it. > > > > see it every boot ? > > > > I don't look every boot. The warning gets scrolled of the screen. > > Once I see the CPU hang warnings I know the boot is failing. I > > don't always look at journalctl later to see what's there. > > I'm going to revert a0747a859ef6 for now, since we're now 8 days into > this and no progress has been made on fixing it. I think this is correct. A If you build the kernel with CONFIG_DEBUG_FS=N, you're definitely going to get the same hang (because the debugfs_ functions fail with -ENODEV and the bdi will never get registered). A This alone leads me to suspect the commit is bogus because it's a randconfig/test accident waiting to happen. We should still root cause the debugfs failure in this case, but I really think debugfs files should be treated as optional, so a failure in setting them up should translate to some sort of warning not a failure to set up the bdi. James -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org