From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-152.mta1.migadu.com [95.215.58.152]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DC0A35DA5D for ; Thu, 27 Aug 2026 03:08:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787800122; cv=none; b=LT3yAXZS0MBVxOTjgyI51h4Al4evgwlgTVr/KRlrWoBe2S0EbFyh7V3DloWd7rTipefR5wDtk5Z/rBbp5Fi6LbEasypAeSS45nel6oF5TH7FcVAQBX9kI9KsHFNKUsIQHMFsPQW4B5bTCs1pFFqnAIN/Y1qdG9KdwqFNPh8Zrm0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787800122; c=relaxed/simple; bh=TBTevkLtBQYfBGrZL7q8D98wBgw40SCkpQHlduNMoPI=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=d5Z9BvTWA/dQaixnXDmSrUnMsGRt3UJrJLrkz9Y2r0gJO2pSDav/yW4Lnfi8MMPS/gmAhHMEaUYFte0mjFXMLtKpef/4UF3xUaxOtKZIRpI23U+Mx0a+ibmfsMC6eXVh9TKndqKRIRuU8DTfGxF+GSfG+j19R7T0joXU59hQ01Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=tLIWahFZ; arc=none smtp.client-ip=95.215.58.152 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="tLIWahFZ" X-Envelope-To: cgroups@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=TBTevkLtBQYfBGrZL7q8D98wBgw40SCkpQHlduNMoPI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787800119; v=1; x=1788404919; b=tLIWahFZd5r7cgmWL3RR7N2eFLVUQvS/eO7RRo64IOZlLgQ4u4BZRXlmnmEjuIXdOSq8VlVR 3t4mdR7o8KDvjwo11aYWN9ui6CiO2l3h84CLTWiazXxk6s7QF82+uOkLQIsU1j0KUu+OiPNt9m6 D7QfgpjWe+myCMkH6bsIiPCc= X-Envelope-To: cgroups@vger.kernel.org Received: from smtpclient.apple (2408:8606:1800:501::1:d) by mta10.migadu.com with ESMTPS id 6175ff980d4bddf9; Thu, 27 Aug 2026 03:08:39 +0000 X-Mizu-Trace-ID: 6175ff980d4bddf9 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.600.51.1.1\)) Subject: Re: [PATCH] mm/memcontrol: fix data-race on reading jiffies_64 From: Muchun Song In-Reply-To: <20260827025457.116191-1-jiayuan.chen@linux.dev> Date: Thu, 27 Aug 2026 11:08:20 +0800 Cc: linux-mm@kvack.org, stable@vger.kernel.org, syzbot+ced4d9a8cadb5ef3adae@syzkaller.appspotmail.com, Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , Yosry Ahmed , Chris Li , Jens Axboe , Jan Kara , Tejun Heo , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <73260DE5-E87A-41BD-BF5F-37163DDD25B4@linux.dev> References: <20260827025457.116191-1-jiayuan.chen@linux.dev> To: Jiayuan Chen X-Mailer: Apple Mail (2.3864.600.51.1.1) > On Aug 27, 2026, at 10:54, Jiayuan Chen = wrote: >=20 > KCSAN reported a data-race between tick_do_update_jiffies64() updating > jiffies_64 and mem_cgroup_flush_stats_ratelimited() reading it = directly. >=20 > Unlike jiffies, jiffies_64 is not volatile, so raw reads are plain > accesses and can even be torn on 32-bit. Use get_jiffies_64() instead, > and fix the same pattern in mem_cgroup_flush_foreign(). >=20 > Cc: > Fixes: 508bed884767 ("mm: memcg: change flush_next_time to = flush_last_time") > Fixes: 97b27821b485 ("writeback, memcg: Implement foreign dirty = flushing") > Reported-by: syzbot+ced4d9a8cadb5ef3adae@syzkaller.appspotmail.com > Signed-off-by: Jiayuan Chen Acked-by: Muchun Song Thanks.