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 73AC0C47082 for ; Mon, 31 May 2021 09:34:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 137FF611AC for ; Mon, 31 May 2021 09:34:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 137FF611AC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7E45A8D0003; Mon, 31 May 2021 05:34:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 796978D0002; Mon, 31 May 2021 05:34:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65D058D0003; Mon, 31 May 2021 05:34:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0084.hostedemail.com [216.40.44.84]) by kanga.kvack.org (Postfix) with ESMTP id 2F2FC8D0002 for ; Mon, 31 May 2021 05:34:30 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C3025181AEF1D for ; Mon, 31 May 2021 09:34:29 +0000 (UTC) X-FDA: 78201015858.25.023399A Received: from outbound-smtp37.blacknight.com (outbound-smtp37.blacknight.com [46.22.139.220]) by imf14.hostedemail.com (Postfix) with ESMTP id 1CED4C00CBD7 for ; Mon, 31 May 2021 09:34:16 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp37.blacknight.com (Postfix) with ESMTPS id 8C70B1ADC 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) X-Rspamd-Queue-Id: 1CED4C00CBD7 Authentication-Results: imf14.hostedemail.com; dkim=none; spf=pass (imf14.hostedemail.com: domain of mgorman@techsingularity.net designates 46.22.139.220 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net; dmarc=none X-Rspamd-Server: rspam03 X-Stat-Signature: 3g1pyndiuk19brt31o6iofsk8ia46gjc X-HE-Tag: 1622453656-244428 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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