From: Wei Fang <fangwei1@huawei.com>
To: Jan Kara <jack@suse.cz>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, hch@infradead.org,
linux-mm@kvack.org, stable@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH] mm: Fix a NULL dereference crash while accessing bdev->bd_disk
Date: Thu, 1 Dec 2016 10:30:05 +0800 [thread overview]
Message-ID: <583F8B2D.8090908@huawei.com> (raw)
In-Reply-To: <20161130095104.GB20030@quack2.suse.cz>
Hi, Jan,
On 2016/11/30 17:51, Jan Kara wrote:
> On Tue 29-11-16 09:58:31, Wei Fang wrote:
>> Hi, Jan,
>>
>> On 2016/11/28 18:07, Jan Kara wrote:
>>> Good catch but I don't like sprinkling checks like this into the writeback
>>> code and furthermore we don't want to call into writeback code when block
>>> device is in the process of being destroyed which is what would happen with
>>> your patch. That is a bug waiting to happen...
>>
>> Agreed. Need another way to fix this problem. I looked through the
>> writeback cgroup code in __filemap_fdatawrite_range(), found if we
>> turn on CONFIG_CGROUP_WRITEBACK, a new crash will happen.
>
> OK, can you test with attached patch please? Thanks!
I've tested this patch with linux-next about 2 hours, and all goes well.
Without this patch, kernel crashes in minutes.
Thanks,
Wei
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next prev parent reply other threads:[~2016-12-01 2:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-26 2:06 [PATCH] mm: Fix a NULL dereference crash while accessing bdev->bd_disk Wei Fang
2016-11-28 10:07 ` Jan Kara
2016-11-28 15:57 ` Tejun Heo
2016-11-29 9:30 ` Jan Kara
2016-11-29 16:43 ` Tejun Heo
2016-11-30 9:50 ` Jan Kara
2016-11-29 1:58 ` Wei Fang
2016-11-30 9:51 ` Jan Kara
2016-12-01 2:30 ` Wei Fang [this message]
2016-12-01 8:18 ` Jan Kara
2016-11-29 23:08 ` Andrew Morton
2016-11-30 7:30 ` Jan Kara
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