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,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 6530CC49361 for ; Thu, 17 Jun 2021 18:02:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4EE78613CE for ; Thu, 17 Jun 2021 18:02:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231602AbhFQSFE (ORCPT ); Thu, 17 Jun 2021 14:05:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:43024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229972AbhFQSFD (ORCPT ); Thu, 17 Jun 2021 14:05:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BC61561241; Thu, 17 Jun 2021 18:02:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623952975; bh=fcHJRF+HkDvnIqayIlyJg+KA7dLX7hNwPHMpsiYp03Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pT7MmJp04q0a1YmU0Q9w5QFKIXr18Znz39NDDpzPBUSZabZOlALqxHXtHdV/m1ebc P7wQPiegEviQb0zFiQ5FHFsNcmEAivSeKnNrXfqRXZFi3b2ozOJM2hnrExcwDUUE2K 4VhteZg29OWN1IthoCRAM5CJNYKbmqTE/veRMbA76lz3QQAgsEwIGO+lkCcMn8jHyM vLxKzJXXpBD3RvlFSxPKaHzzO6y3iOzG5ybLmoQke+aIJHbLnZtPTjRjxqoF4MQOh3 4F90jcmKKhZ5pIk3f/7so+RahCpv9eUm3LTJ8Rem2NgbANQ/jdXymYHs8QKc17qMue mnjZ8lBWhP1wQ== Date: Thu, 17 Jun 2021 11:02:50 -0700 From: Nathan Chancellor To: "Aneesh Kumar K.V" , Andrew Morton Cc: Matthew Wilcox , Naresh Kamboju , linux-next@vger.kernel.org, clang-built-linux@googlegroups.com, lkft-triage@lists.linaro.org, linux-kernel@vger.kernel.org, Nick Desaulniers , Arnd Bergmann , Stephen Rothwell Subject: Re: [next] [clang] x86_64-linux-gnu-ld: mm/mremap.o: in function `move_pgt_entry': mremap.c:(.text+0x763): undefined reference to `__compiletime_assert_342' Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rebuilt the CC list because most people were added based on the incorrect bisect result. On Thu, Jun 17, 2021 at 02:51:49PM +0100, Matthew Wilcox wrote: > On Thu, Jun 17, 2021 at 06:15:45PM +0530, Naresh Kamboju wrote: > > On Thu, 17 Jun 2021 at 17:41, Naresh Kamboju wrote: > > > x86_64-linux-gnu-ld: mm/mremap.o: in function `move_pgt_entry': > > > mremap.c:(.text+0x763): undefined reference to `__compiletime_assert_342' > > > > The git bisect pointed out the first bad commit. > > > > The first bad commit: > > commit 928cf6adc7d60c96eca760c05c1000cda061604e > > Author: Stephen Boyd > > Date: Thu Jun 17 15:21:35 2021 +1000 > > module: add printk formats to add module build ID to stacktraces > > Your git bisect probably went astray. There's no way that commit > caused that regression. My bisect landed on commit 83f85ac75855 ("mm/mremap: convert huge PUD move to separate helper"). flush_pud_tlb_range() evaluates to BUILD_BUG() when CONFIG_TRANSPARENT_HUGEPAGE is unset but this function is present just based on the value of CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD. $ make -skj(nproc) ARCH=x86_64 CC=clang O=build/x86_64 distclean allnoconfig mm/mremap.o $ llvm-readelf -s build/x86_64/mm/mremap.o &| rg __compiletime_assert 21: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND __compiletime_assert_337 $ rg TRANSPARENT_ build/x86_64/.config 450:CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y 451:CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y 562:# CONFIG_TRANSPARENT_HUGEPAGE is not set Not sure why this does not happen on newer clang versions, presumably something with inlining decisions? Still seems like a legitimate issue to me. Cheers, Nathan