Date: Mon, 23 Nov 2015 16:13:22 -0500
From: Tejun Heo <tj@kernel.org>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: axboe@fb.com, jack@suse.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>, "Theodore Ts'o" <tytso@mit.edu>
Subject: Re: BUG:  Unable to handle kernel paging request for data at address
 __percpu_counter_add
Message-ID: <20151123211322.GD19072@mtj.duckdns.org>
References: <564DA363.9060303@linux.vnet.ibm.com>
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Hello,

On Thu, Nov 19, 2015 at 03:54:35PM +0530, Raghavendra K T wrote:
> While I was creating thousands of docker container on a power8 baremetal
> (config: 4.3.0 kernel 1TB RAM, 20core (=160 cpu) system. After creating
> around 5600 container
> I have hit below problem.
> [This is looking similar to
> https://bugzilla.kernel.org/show_bug.cgi?id=101011, but
> kernel had Revert "ext4: remove block_device_ejected" (bdfe0cbd746aa9) since
> it is 4.3.0 tagged kernel]
> 
> Any hints on how to go about the fix. Please let me know if you think any
> more information needed.
> 
> docker daemon is device mapper based. (and it took a day to recreate the
> problem)
> 
> [ by disabling  CONFIG_BLK_CGROUP and CONFIG_CGROUP_WRITEBACK I am able to
> create 10k containers without any problem]

Could be the same problem that Ilya is trying to fix.  ie. blkdev i_wb
pointing to a stale wb.  Can you please see whether the following
patch resolves the issue?

 http://lkml.kernel.org/g/1448054554-24138-1-git-send-email-idryomov@gmail.com

Thanks.

-- 
tejun
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