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Date:   Wed, 18 May 2022 16:29:35 -0600
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Subject: Re: [PATCH] blk-cgroup: Remove unnecessary rcu_read_lock/unlock()
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To:     Marek Szyprowski <m.szyprowski@samsung.com>, bh1scw@gmail.com,
        tj@kernel.org
Cc:     cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, songmuchun@bytedance.com
References: <20220516173930.159535-1-bh1scw@gmail.com>
 <CGME20220518192850eucas1p1458c00d4917c5ed39f2c37c9eb30cd46@eucas1p1.samsung.com>
 <46253c48-81cb-0787-20ad-9133afdd9e21@samsung.com>
From:   Jens Axboe <axboe@kernel.dk>
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On 5/18/22 1:28 PM, Marek Szyprowski wrote:
> On 16.05.2022 19:39, bh1scw@gmail.com wrote:
>> From: Fanjun Kong <bh1scw@gmail.com>
>>
>> spin_lock_irq/spin_unlock_irq contains preempt_disable/enable().
>> Which can serve as RCU read-side critical region, so remove
>> rcu_read_lock/unlock().
>>
>> Signed-off-by: Fanjun Kong <bh1scw@gmail.com>
> 
> This patch landed in today's linux next-20220518 as commit 77c570a1ea85 
> ("blk-cgroup: Remove unnecessary rcu_read_lock/unlock()").
> 
> Unfortunately it triggers the following warning on ARM64 based Raspberry 
> Pi 4B board:>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at block/blk-cgroup.c:301 blkg_create+0x398/0x4e0

Should this use rcu_read_lock_any_held() rather than rcu_read_lock_held()?

-- 
Jens Axboe