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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,USER_AGENT_SANE_1 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 2E6E6C49EA6 for ; Wed, 23 Jun 2021 23:41:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11A98611C9 for ; Wed, 23 Jun 2021 23:41:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229924AbhFWXoO (ORCPT ); Wed, 23 Jun 2021 19:44:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:39604 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229812AbhFWXoM (ORCPT ); Wed, 23 Jun 2021 19:44:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 40BB3611AC; Wed, 23 Jun 2021 23:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624491714; bh=iKHrbK2LLQgN0Vdey8aEtJKullSH9rF7grmndIc1hdY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=GsX1V/vmv/e6V3h7NTdfNlp+jfqOcZGm3yVnqd3kI1/3zE72MTKA9bBbIj7kv1+j8 zcPkeIsOT370uT2evCiRmEA+HPJJtffjEISbtB3/8karSfOmlVN4tZdpOtj/+8Gm2K W1XZfEL6OCprmSI00HPByWVM/xPHRWS8mRhmBUPqLEPdyIp4QzhK7oBBUphieUIbAu Os3ijOSqu7fw/kUPclFm+rYsG7SqEmTxQA4uOfnjqhK9L5iSq1q+GKuBjepkJ7IONk ptBVQLXKevt8gOFZi1R/3NqWLoTE3Cf58EjJQAc2nr2gJXz0gTfWv8G5r9So741Iew K88cgu6YBRioQ== Subject: Re: Build failure in -next To: paulmck@kernel.org, aneesh.kumar@linux.ibm.com Cc: linux-kernel@vger.kernel.org, linux-next@vger.kernel.org, sfr@canb.auug.org.au, elver@google.com, ndesaulniers@google.com, clang-built-linux@googlegroups.com References: <20210623223015.GA315292@paulmck-ThinkPad-P17-Gen-1> From: Nathan Chancellor Message-ID: <5b55b544-67de-871d-465c-af3c8be203c3@kernel.org> Date: Wed, 23 Jun 2021 16:41:53 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210623223015.GA315292@paulmck-ThinkPad-P17-Gen-1> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, On 6/23/2021 3:30 PM, Paul E. McKenney wrote: > Hello, Aneesh! > > Yesterday evening's next-20210622 testing gave me the following > kernel-build error: > > ld: mm/mremap.o: in function `move_huge_pud': > /home/git/linux-next/mm/mremap.c:372: undefined reference to `__compiletime_assert_395' > > Bisection landed on this commit: > > 257121c5aabe ("mm/mremap: convert huge PUD move to separate helper") > > I have no idea how this commit relates to that error message, but > reverting this commit on top of next-20210622 really does get rid of > the problem. This was reported by Naresh Kamboju last week: https://lore.kernel.org/r/CA+G9fYsWHE5Vu9T3FV-vtHHbVFJWEF=bmjQxwaZs3uVYef028g@mail.gmail.com/ It seems to be related to the fact that older versions of clang cannot figure out that the HPAGE_PUD case in move_pgt_entry() is never called when CONFIG_TRANSPARENT_HUGE is unset so it is not eliminated, which is problematic because flush_pud_tlb_range() evaluates to BUILD_BUG() in that case, which is called within move_huge_pud(). > The following reproducer provokes this error: > > tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --torture lock --configs LOCK07 --build-only --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --kmake-arg "CC=clang-11" > > Run the above command in the top-level directory of your -next source > tree, and using this compiler: > > $ clang-11 -v > Ubuntu clang version 11.1.0-++20210428103817+1fdec59bffc1-1~exp1~20210428204431.166 > Target: x86_64-pc-linux-gnu > > Thoughts? Aneesh had a patch in that thread above that would resolve the issue, it just needs to be sent to Andrew for a fixup patch. Cheers, Nathan