From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E419B13AC4 for ; Mon, 26 Jun 2023 18:29:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60378C433C8; Mon, 26 Jun 2023 18:29:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687804159; bh=F4Fov9c1gQrz7jghtVneAvVJDKLt0AAP3W/pqdwPAuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HiKhbTKBKsQrA0cWIU28plaz1czs6IatbCyHFrY2s6YV/MRPsENWGglfJ/iEvRfQ7 YlTem7kCcyItFjKMDAUW1rL4pFb4ngf87Dt/PtFFBCDZDPodeLDrHKgzfPFaluwQow J63m/dgkns7AajKMjG13431Cy3AtotI+56uy4k5I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Tetsuo Handa , Tejun Heo Subject: [PATCH 6.1 062/170] cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex in freezer_css_{online,offline}() Date: Mon, 26 Jun 2023 20:10:31 +0200 Message-ID: <20230626180803.362954133@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230626180800.476539630@linuxfoundation.org> References: <20230626180800.476539630@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Tetsuo Handa commit f0cc749254d12c78e93dae3b27b21dc9546843d0 upstream. syzbot is again reporting circular locking dependency between cpu_hotplug_lock and freezer_mutex. Do like what we did with commit 57dcd64c7e036299 ("cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex"). Reported-by: syzbot Closes: https://syzkaller.appspot.com/bug?extid=2ab700fe1829880a2ec6 Signed-off-by: Tetsuo Handa Tested-by: syzbot Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Cc: stable@vger.kernel.org # v6.1+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/legacy_freezer.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/kernel/cgroup/legacy_freezer.c +++ b/kernel/cgroup/legacy_freezer.c @@ -108,16 +108,18 @@ static int freezer_css_online(struct cgr struct freezer *freezer = css_freezer(css); struct freezer *parent = parent_freezer(freezer); + cpus_read_lock(); mutex_lock(&freezer_mutex); freezer->state |= CGROUP_FREEZER_ONLINE; if (parent && (parent->state & CGROUP_FREEZING)) { freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN; - static_branch_inc(&freezer_active); + static_branch_inc_cpuslocked(&freezer_active); } mutex_unlock(&freezer_mutex); + cpus_read_unlock(); return 0; } @@ -132,14 +134,16 @@ static void freezer_css_offline(struct c { struct freezer *freezer = css_freezer(css); + cpus_read_lock(); mutex_lock(&freezer_mutex); if (freezer->state & CGROUP_FREEZING) - static_branch_dec(&freezer_active); + static_branch_dec_cpuslocked(&freezer_active); freezer->state = 0; mutex_unlock(&freezer_mutex); + cpus_read_unlock(); } static void freezer_css_free(struct cgroup_subsys_state *css)