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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 F3A5CC47094 for ; Mon, 31 May 2021 09:34:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1F6C61008 for ; Mon, 31 May 2021 09:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231160AbhEaJgH (ORCPT ); Mon, 31 May 2021 05:36:07 -0400 Received: from outbound-smtp63.blacknight.com ([46.22.136.252]:48485 "EHLO outbound-smtp63.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230479AbhEaJgF (ORCPT ); Mon, 31 May 2021 05:36:05 -0400 Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp63.blacknight.com (Postfix) with ESMTPS id 7C545FADAE for ; Mon, 31 May 2021 10:34:24 +0100 (IST) Received: (qmail 12408 invoked from network); 31 May 2021 09:34:24 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.255]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 31 May 2021 09:34:24 -0000 Date: Mon, 31 May 2021 10:34:23 +0100 From: Mel Gorman To: Andrii Nakryiko Cc: akpm@linux-foundation.org, bpf@vger.kernel.org, msuchanek@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, hritikxx8@gmail.com, jolsa@kernel.org, kernel-team@fb.com, Arnaldo Carvalho de Melo , Hao Luo Subject: Re: [PATCH] kbuild: skip per-CPU BTF generation for pahole v1.18-v1.21 Message-ID: <20210531093422.GS30378@techsingularity.net> References: <20210530002536.3193829-1-andrii@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20210530002536.3193829-1-andrii@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 29, 2021 at 05:25:36PM -0700, Andrii Nakryiko wrote: > Commit "mm/page_alloc: convert per-cpu list protection to local_lock" > introduced a zero-sized per-CPU variable, which causes pahole to generate > invalid BTF. Only pahole versions 1.18 through 1.21 are impacted, as before > 1.18 pahole doesn't know anything about per-CPU variables, and 1.22 contains > the proper fix for the issue. > > Luckily, pahole 1.18 got --skip_encoding_btf_vars option disabling BTF > generation for per-CPU variables in anticipation of some unanticipated > problems. So use this escape hatch to disable per-CPU var BTF info on those > problematic pahole versions. Users relying on availability of per-CPU var BTFs > would need to upgrade to pahole 1.22+, but everyone won't notice any > regressions. > > Cc: Mel Gorman > Cc: Arnaldo Carvalho de Melo > Cc: Hao Luo > Signed-off-by: Andrii Nakryiko Acked-by: Mel Gorman -- Mel Gorman SUSE Labs