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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FECCECAA25 for ; Thu, 25 Aug 2022 17:44:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242894AbiHYRom (ORCPT ); Thu, 25 Aug 2022 13:44:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239861AbiHYRoj (ORCPT ); Thu, 25 Aug 2022 13:44:39 -0400 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE7E6B6D2A for ; Thu, 25 Aug 2022 10:44:38 -0700 (PDT) Received: by mail-pl1-x62f.google.com with SMTP id io24so5852748plb.1 for ; Thu, 25 Aug 2022 10:44:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc; bh=ywmy6tC4a8AFm3DYCGlNXvDbFK6O2fsc7cCstl/Zw4w=; b=ZTy3Iixf4EgulBk9eX/Zd5TCVbgnBAyLv5v/ctOEOV1jWT3q07bxvemAbhrjmbnxC1 0mtt2gBrF/1VfSPN0xm0QF9x7dzoGtYGWsIgQzpDj9NMTP7RgRoXL4R4Jg2k2mDfqLvD IGYslx0hJeDaLfYKSbDjKziBL0/aBVhIkIBypSBG+jG10MtpE8mKs1I7zf+V6hAB2qTH Ey6ubMna4RSV7WpajSx4G4+t7HDZPN+KE2HhRujPGTISpkTpSGcwUQgmfLiDQD1yqazp QBgJvavu23VKPW/fvXiuVs/XDF7eo7YRz6S7ENiP2c2XDBFWsHBT/UeZeyS257Od3zWN xjbA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc; bh=ywmy6tC4a8AFm3DYCGlNXvDbFK6O2fsc7cCstl/Zw4w=; b=j4+/hUD84REQRggMRgcbMbOue+U3jNHRedM4j55MGcmS4z9r8fa+jL/wcK8qVxA6xb aDkfioulFN7RqGsjmyzCCqvAJjjt6ZzkBlcTcgUs6FuSwyX1KyzVCvM+24sws7z0zGft Mzy0OZpuObgVdRjA79s/KuyHgwQIYiOOsFH3CrmIIScFYuaqLk3IQubmcTlxRlhb6HE2 qUXkS84ooMOi/Sk/Vb7PatdjEz9XeAG8cyjvZIQ+TVQ07kDRbE9j0E26UnJAKZcPwvo1 0j6gVZ50t+U5ChMqVrltd+/R5eq4kutfqUrghlogTJgQVfeXnccGmnv16YZ5OfqKl6JQ qviQ== X-Gm-Message-State: ACgBeo2gUhm+UpXBqEAdY4mNquU1mHaVMuX3wSRDNAGqdANtbfwbEPjg jLHvUUMaatR2Qr4rHOLntRk= X-Google-Smtp-Source: AA6agR50eAwdxfHFqnm1CltXt/HOMr43FHryzBuGGoE9wRuQ+gkeC7dIbFIJGRFtCbMevo013xV/Ig== X-Received: by 2002:a17:902:ce91:b0:172:c2c4:e6be with SMTP id f17-20020a170902ce9100b00172c2c4e6bemr187471plg.99.1661449478245; Thu, 25 Aug 2022 10:44:38 -0700 (PDT) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id p64-20020a625b43000000b005379fb50ff0sm1460192pfb.50.2022.08.25.10.44.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Aug 2022 10:44:37 -0700 (PDT) Sender: Tejun Heo Date: Thu, 25 Aug 2022 07:44:36 -1000 From: Tejun Heo To: Tetsuo Handa Cc: Imran Khan , Xuewen Yan , syzbot , linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() Message-ID: References: <0000000000009ebf5605e6ff48d5@google.com> <0000000000000bc13705e702955b@google.com> 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 On Thu, Aug 25, 2022 at 05:38:38PM +0900, Tetsuo Handa wrote: > syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at > cpuset_attach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix > threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that > cpuset_attach() is also called from cgroup_attach_task_all(). > Add cpus_read_lock() like what cgroup_procs_write_start() does. > > Link: https://syzkaller.appspot.com/bug?extid=29d3a3b4d86c8136ad9e [1] > Reported-by: syzbot > Signed-off-by: Tetsuo Handa > Fixes: 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") Applied to cgroup/for-6.0-fixes and sent pull request. > Waiting for test result from syzbot. Should we remove "static" from > cgroup_attach_lock() and call from cgroup_attach_task_all() ? Yeah, that probably is better. Can you spin up a follow up patch? Thanks. -- tejun