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Date:   Wed, 13 Nov 2019 08:35:01 -0800
From:   Tejun Heo <tj@kernel.org>
To:     Faiz Abbas <faiz_abbas@ti.com>
Cc:     axboe@kernel.dk, cgroups@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        lizefan@huawei.com, hannes@cmpxchg.org, kernel-team@fb.com,
        Dan Schatzberg <dschatzberg@fb.com>, Daniel Xu <dlxu@fb.com>
Subject: Re: [PATCH 5/6] blk-cgroup: reimplement basic IO stats using cgroup
 rstat
Message-ID: <20191113163501.GI4163745@devbig004.ftw2.facebook.com>
References: <20191107191804.3735303-1-tj@kernel.org>
 <20191107191804.3735303-6-tj@kernel.org>
 <cd3ebcee-6819-a09b-aeba-de6817f32cde@ti.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

Can you please see whether the following patch fixes the issue?

Thanks.

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 48a66738143d..19394c77ed99 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -626,7 +626,8 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q,
 		bis->cur.ios[rwd]++;
 
 		u64_stats_update_end(&bis->sync);
-		cgroup_rstat_updated(blkg->blkcg->css.cgroup, cpu);
+		if (cgroup_subsys_on_dfl(io_cgrp_subsys))
+			cgroup_rstat_updated(blkg->blkcg->css.cgroup, cpu);
 		put_cpu();
 	}