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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49998C3DA5D for ; Mon, 22 Jul 2024 17:52:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 83A886B0085; Mon, 22 Jul 2024 13:52:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7C3906B0088; Mon, 22 Jul 2024 13:52:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63D456B0089; Mon, 22 Jul 2024 13:52:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 457086B0085 for ; Mon, 22 Jul 2024 13:52:28 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id BAC611C37E3 for ; Mon, 22 Jul 2024 17:52:27 +0000 (UTC) X-FDA: 82368133134.15.8BC831B Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) by imf19.hostedemail.com (Postfix) with ESMTP id D35691A001D for ; Mon, 22 Jul 2024 17:52:25 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=TvnInn1j; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf19.hostedemail.com: domain of htejun@gmail.com designates 209.85.214.182 as permitted sender) smtp.mailfrom=htejun@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1721670694; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=d8H1pDCmGySCGRl1gIUJ/4C+Z1BCsXQ3ICifUIskDw4=; b=JtvGcvu2f9jxqxOqkFK8j5g+WgZNuNGCjYqgwcKmQDOekfrs+piUWl1gMNTdWh8Pfq3ZnJ dXyEJOKDhfYDLvqaBurTPwZkSzzE33KjYvPyTRHDZ8/yhXa5fa4+25A8CMf4mbOFrsnnWw XL7/RhPV7sGveXwfGvT4NJGQqQ8ap9c= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1721670694; a=rsa-sha256; cv=none; b=ey+nebz5ieHsTJbuPddWgHuNwPrCR79kJH5PEwGK0By27Ea/LgJQ54+glzY5olbR6bcf3X CMuN7Kgy+PkMJNK98W+pAkcAvsOLHRWZIBfUJ4J8TYOgAQZ73TE4TMx6C4tiIfCC2vAqHP CUIkYG+BuxWCjRIE8rlxdkh/MAKc0jc= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=TvnInn1j; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none); spf=pass (imf19.hostedemail.com: domain of htejun@gmail.com designates 209.85.214.182 as permitted sender) smtp.mailfrom=htejun@gmail.com Received: by mail-pl1-f182.google.com with SMTP id d9443c01a7336-1fd640a6454so22435685ad.3 for ; Mon, 22 Jul 2024 10:52:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1721670744; x=1722275544; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=d8H1pDCmGySCGRl1gIUJ/4C+Z1BCsXQ3ICifUIskDw4=; b=TvnInn1jwUyUT92LpRguvz2YwD1F5n6ahBTaK/ebgE0fgpZW58Gm18JoMfWWcJGM+c +xXcsXn2W7piCjcGU803J9cH9bOUIPMuUOd+Wi/WDmzFlEZd5rvkn+l+DnGZbAh/Kj/X 9cMEDnkiJD90D7o2kqw/boydRrfsqAZgMAWDVy0beo/Hpim9aKFM5HeiAoULdq0WuDFg 5Ph3vR3ACui1WSgBVbA84JHWdK07qIjWRdIw2d9vBA+8faNyFl9BsGA+E389+7LcVCl9 Q9jjlxgGdCtZ65gFlXVHbbH/BCbwZpMvaEDKhy8Fbc8d3TFlVeRwP5HU7m1VR4NhLise sYvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721670744; x=1722275544; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=d8H1pDCmGySCGRl1gIUJ/4C+Z1BCsXQ3ICifUIskDw4=; b=L1+GZuq7/cBE8GFxbxC6Dw3I9vvJU3AdbRzeL/oudv3IFy8hkWKkVsui3xPiOsTEyU a95Zb4WvbXvuU4MasGjEtC9DuiqL00cK4+/qQmbdqvAsr+/oaal4nCo4Ko+sibSyLGkd u3IZGvfJHSgaU8suzPhBpLgfKE71Mjp4gOF4pDLcNi5OPaxxMXQ8RJfHNS9glbW2lZGD nErWSXyLIxRZA58X6LJFbdB6FEgjZZtgOLEqat/3TsYA+yXHjrT0vTxHDHLVGNF+Z3pO t/fajvP6O/eYRo6Mj0BZKg9D5Kr8tiTzORxi8Fe4ffveB2RMJ6y0Z+6sc/mQ7/iJNnCc ol0Q== X-Forwarded-Encrypted: i=1; AJvYcCUgW14mNhiGDSEbklaDIfQtDfF4gaPFHat9ZgCpwwB39u8zqJ/Kb1j31ZHz1qARpuBHF2arWutNk1EfnnJJ9iztEWw= X-Gm-Message-State: AOJu0YxLVskwuRfk9/qDL/SGd6O3b2vaaJOmB8es2Q/mDP1pQQzgGGtY Gyn1dzp/NpJ/n9uroRMBnP7WPsEfB+J/XXN2BpBKBz2ik0AssJhl X-Google-Smtp-Source: AGHT+IFvaw5S9BVXgTqGeEVg+R+dGHoF2WCukfAlPmBJGv5XsrOt33aHMZ4o5pvjoGjnzEfmXGKPhA== X-Received: by 2002:a17:903:41cb:b0:1fd:95ac:506b with SMTP id d9443c01a7336-1fd95ac51f0mr26766915ad.64.1721670744351; Mon, 22 Jul 2024 10:52:24 -0700 (PDT) Received: from localhost (dhcp-141-239-149-160.hawaiiantel.net. [141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fd6f316d0fsm57840575ad.165.2024.07.22.10.52.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jul 2024 10:52:23 -0700 (PDT) Date: Mon, 22 Jul 2024 07:52:22 -1000 From: Tejun Heo To: Boqun Feng Cc: kernel test robot , Suren Baghdasaryan , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Kent Overstreet , Kees Cook , Alexander Viro , Alex Gaynor , Alice Ryhl , Andreas Hindborg , Benno Lossin , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Christoph Lameter , Dennis Zhou , Gary Guo , Miguel Ojeda , Pasha Tatashin , Peter Zijlstra , Vlastimil Babka , Wedson Almeida Filho , linux-mm@kvack.org, lkmm@lists.linux.dev Subject: Re: [linus:master] [mm] 24e44cc22a: BUG:KCSAN:data-race_in_pcpu_alloc_noprof/pcpu_block_update_hint_alloc Message-ID: References: <202407191651.f24e499d-oliver.sang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D35691A001D X-Stat-Signature: ui4ioh7385i5ca89uhguzmx6pen6qot1 X-Rspam-User: X-HE-Tag: 1721670745-172898 X-HE-Meta: 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 /G3D2524 N8G/+SQ4KqXCZf/rGgfWx+EyPRbyrmup6NvHJk+XrvdkmVcb2pYu3e/HagjgDJ7pLmiVtu0+vHap+DeBWgAdF/FpgUe+J70Shw+AAGww/urc/aF+B2Gi1l1p7F9gZsQG4F+YKB0nwPPjmw19CZ3vMH1rL1+npC0w4wXywXl2Y+Gqlig3k67JPrtXjwEIhc1UzEfekgpqwEUyJY1bpvYbcl+Gc4UYpVpq+Pw284GypjC7+9Jn0+CtKBhalLbqGSyKEjkcIwkWddd97gZdQJViKfuI1yq0fUfhvqdoM3yVGJp7tHxoX5bt3x5XaXlhCLdH1x9QgWa3lm5p2sHDkoTVFha1iNevsrSSYUrriXd1Ywb6QGHb1TmallX6mOS9bcf62c1fQPQPwYRbLJQTJjyVCTykczXaYNFGQbSP84eSkmNG0qfAk9/5/4Jc+VwwRkrmczCQzM/WY15YGEGlL0qxsH2+qvBTQBcVIxDvS4JHfhqh2IYC/3A7lMTvVDKjebffrUiVB0EUA2h/flZXlDT/vgA3MmSemugtMbg69Ozlnq2cBn029cC2yvB37YdbAJuUh3XwSM6FzUiIYJdNSz+ZRYT0j3NJl/Cab7TDk 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: List-Subscribe: List-Unsubscribe: On Mon, Jul 22, 2024 at 10:47:30AM -0700, Boqun Feng wrote: > This looks like a data race because we read pcpu_nr_empty_pop_pages out > of the lock for a best effort checking, @Tejun, maybe you could confirm > on this? That does sound plausible. > - if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) > + /* > + * Checks pcpu_nr_empty_pop_pages out of the pcpu_lock, data races may > + * occur but this is just a best-effort checking, everything is synced > + * in pcpu_balance_work. > + */ > + if (data_race(pcpu_nr_empty_pop_pages) < PCPU_EMPTY_POP_PAGES_LOW) > pcpu_schedule_balance_work(); Would it be better to use READ/WRITE_ONCE() for the variable? Thanks. -- tejun