From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v2 1/4] cgroup/cpuset: Fix partition root's cpuset.cpus update bug Date: Fri, 17 Mar 2023 11:15:05 -0400 Message-ID: <20230317151508.1225282-2-longman@redhat.com> References: <20230317151508.1225282-1-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679066133; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yyPOMwQLISxSVk5Hax7mBc5lUymcLlOh64gwiaoZAvQ=; b=N/RkptS5aI2xMFm9zDcpLDq6Q1+TBXYIKFRNCAcjfERZltj156vNlXDdWjStoDyEv0xm0i 4UhKCbqYO2KmsI+MrQeWj+t3YIR2eKKDzHb4i9HiGn1nGOke4kzoSdKwnOpirtfmjv6pfp bhda/HJX2Gr/TCBLX//IJklwCUehJvY= In-Reply-To: <20230317151508.1225282-1-longman@redhat.com> List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo , Zefan Li , Johannes Weiner , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Will Deacon , Peter Zijlstra , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Juri Lelli , Waiman Long It was found that commit 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug that corrupted "cpuset.cpus" of a partition root when it was updated. It is because the tmp->new_cpus field of the passed tmp parameter of update_parent_subparts_cpumask() should not be used at all as it contains important cpumask data that should not be overwritten. Fix it by using tmp->addmask instead. Also update update_cpumask() to make sure that trialcs->cpu_allowed will not be corrupted until it is no longer needed. Fixes: 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task") Signed-off-by: Waiman Long --- kernel/cgroup/cpuset.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 636f1c682ac0..f310915d1257 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1513,7 +1513,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, spin_unlock_irq(&callback_lock); if (adding || deleting) - update_tasks_cpumask(parent, tmp->new_cpus); + update_tasks_cpumask(parent, tmp->addmask); /* * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary. @@ -1770,10 +1770,13 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, /* * Use the cpumasks in trialcs for tmpmasks when they are pointers * to allocated cpumasks. + * + * Note that update_parent_subparts_cpumask() uses only addmask & + * delmask, but not new_cpus. */ tmp.addmask = trialcs->subparts_cpus; tmp.delmask = trialcs->effective_cpus; - tmp.new_cpus = trialcs->cpus_allowed; + tmp.new_cpus = NULL; #endif retval = validate_change(cs, trialcs); @@ -1838,6 +1841,11 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, } spin_unlock_irq(&callback_lock); +#ifdef CONFIG_CPUMASK_OFFSTACK + /* Now trialcs->cpus_allowed is available */ + tmp.new_cpus = trialcs->cpus_allowed; +#endif + /* effective_cpus will be updated here */ update_cpumasks_hier(cs, &tmp, false); -- 2.31.1