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Date:   Tue, 28 Feb 2023 19:37:08 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Hou Tao <houtao@huaweicloud.com>
Cc:     stable@vger.kernel.org, linux-raid@vger.kernel.org,
        David Sloan <david.sloan@eideticom.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Song Liu <song@kernel.org>, Jens Axboe <axboe@kernel.dk>,
        Sasha Levin <sashal@kernel.org>, houtao1@huawei.com
Subject: Re: [PATCH 5.10] md: Flush workqueue md_rdev_misc_wq in md_alloc()
Message-ID: <Y/5J1KXCvSPuJs4C@kroah.com>
References: <20230224065209.3170104-1-houtao@huaweicloud.com>
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On Fri, Feb 24, 2023 at 02:52:09PM +0800, Hou Tao wrote:
> From: David Sloan <david.sloan@eideticom.com>
> 
> commit 5e8daf906f890560df430d30617c692a794acb73 upstream.
> 
> A race condition still exists when removing and re-creating md devices
> in test cases. However, it is only seen on some setups.
> 
> The race condition was tracked down to a reference still being held
> to the kobject by the rdev in the md_rdev_misc_wq which will be released
> in rdev_delayed_delete().
> 
> md_alloc() waits for previous deletions by waiting on the md_misc_wq,
> but the md_rdev_misc_wq may still be holding a reference to a recently
> removed device.
> 
> To fix this, also flush the md_rdev_misc_wq in md_alloc().
> 
> Signed-off-by: David Sloan <david.sloan@eideticom.com>
> [logang@deltatee.com: rewrote commit message]
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Song Liu <song@kernel.org>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
> Hi Greg,
> 
> We found the problem also exists on v5.10, so could you please pick it up
> for v5.10 ?

Now queued up, thanks.

greg k-h