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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 2AB9DC4646F for ; Sat, 4 Aug 2018 18:19:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DDFF7217CB for ; Sat, 4 Aug 2018 18:19:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DDFF7217CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729682AbeHDUVW (ORCPT ); Sat, 4 Aug 2018 16:21:22 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42444 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728054AbeHDUVW (ORCPT ); Sat, 4 Aug 2018 16:21:22 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 67301401B1EA; Sat, 4 Aug 2018 18:19:51 +0000 (UTC) Received: from localhost (unknown [10.18.25.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 445092026D66; Sat, 4 Aug 2018 18:19:51 +0000 (UTC) Date: Sat, 4 Aug 2018 14:19:51 -0400 From: Mike Snitzer To: Linus Torvalds Cc: wgh@torlan.ru, Theodore Ts'o , Jens Axboe , Sagi Grimberg , Linux Kernel Mailing List , linux-block , dm-devel@redhat.com, Ilya Dryomov , Zdenek Kabelac Subject: Re: LVM snapshot broke between 4.14 and 4.16 Message-ID: <20180804181950.GA10514@redhat.com> References: <1ec0a220-d5b0-1c27-e63b-c4d3f4ce9d77@torlan.ru> <20180803133102.GA3092@redhat.com> <20180803152034.GD32066@thunk.org> <20180803183932.GA3258@redhat.com> <20180803190617.GA4498@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Sat, 04 Aug 2018 18:19:51 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Sat, 04 Aug 2018 18:19:51 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'msnitzer@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 04 2018 at 1:04pm -0400, Linus Torvalds wrote: > On Sat, Aug 4, 2018 at 3:03 AM WGH wrote: > > > > > > > The patch works for me. > > > > However, there's no text messsage in the kernel log, just a traceback. I > > think that's because WARN_ONCE is supposed to take condition as a first > > argument. > > Duh. > > It needs to be WARN_ONCE(1, ...); > > I obviously didn't test that patch, but I _did_ compile it. I wonder > why I didn't get a compiler warning for it... > > [ Goes off and looks ] > > Oh, because the "bio_devname(bio, b)" argument ended up being > interpreted as the format string, and since it was a dynamic string > the compiler felt it was all fine. Just bad luck. > > Anyway, just out of curiosity, what was the traceback? > > I'm not entirely happy with that patch either (even after the obvious > fix to add the "1" argument), but it does seem like the minimal > temporary workaround for now. I agree. Please feel free to add my: Acked-by: Mike Snitzer