From: Logan Gunthorpe <logang@deltatee.com>
To: Guoqing Jiang <guoqing.jiang@linux.dev>,
Yu Kuai <yukuai1@huaweicloud.com>,
song@kernel.org
Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
yukuai3@huawei.com, yi.zhang@huawei.com
Subject: Re: [PATCH -next 2/3] md/raid10: convert resync_lock to use seqlock
Date: Thu, 1 Sep 2022 18:56:06 -0600 [thread overview]
Message-ID: <cd0170a7-86ab-ebb3-0aed-93b2e18be432@deltatee.com> (raw)
In-Reply-To: <917c01c1-1e2b-66f9-69f1-ed706b7ffc8f@linux.dev>
On 2022-09-01 18:49, Guoqing Jiang wrote:
>
>
> On 9/2/22 2:41 AM, Logan Gunthorpe wrote:
>> Hi,
>>
>> On 2022-08-29 07:15, Yu Kuai wrote:
>>> From: Yu Kuai <yukuai3@huawei.com>
>>>
>>> Currently, wait_barrier() will hold 'resync_lock' to read
>>> 'conf->barrier',
>>> and io can't be dispatched until 'barrier' is dropped.
>>>
>>> Since holding the 'barrier' is not common, convert 'resync_lock' to use
>>> seqlock so that holding lock can be avoided in fast path.
>>>
>>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> I've found some lockdep issues starting with this patch in md-next while
>> running mdadm tests (specifically 00raid10 when run about 10 times in a
>> row).
>>
>> I've seen a couple different lock dep errors. The first seems to be
>> reproducible on this patch, then it possibly changes to the second on
>> subsequent patches. Not sure exactly.
>
> That's why I said "try mdadm test suites too to avoid regression." ...
You may have to run it multiple times, a single run tends not to catch
all errors. I had to loop the noted test 10 times to be sure I hit this
every time when I did the simple bisect.
And ensure that all the debug options are on when you run it (take a
look at the Kernel Hacking section in menuconfig). You won't hit this
bug without at least CONFIG_PROVE_LOCKING=y.
Logan
next prev parent reply other threads:[~2022-09-02 0:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-29 13:14 [PATCH -next 0/3] md/raid10: reduce lock contention for io Yu Kuai
2022-08-29 13:15 ` [PATCH -next 1/3] md/raid10: fix improper BUG_ON() in raise_barrier() Yu Kuai
2022-08-29 19:53 ` John Stoffel
2022-08-30 1:01 ` Yu Kuai
2022-08-30 6:32 ` Paul Menzel
2022-08-29 13:15 ` [PATCH -next 2/3] md/raid10: convert resync_lock to use seqlock Yu Kuai
2022-09-01 18:41 ` Logan Gunthorpe
2022-09-02 0:49 ` Guoqing Jiang
2022-09-02 0:56 ` Logan Gunthorpe [this message]
2022-09-02 1:00 ` Guoqing Jiang
2022-09-02 1:21 ` Yu Kuai
2022-09-02 8:14 ` Yu Kuai
2022-09-02 17:03 ` Logan Gunthorpe
2022-09-03 6:07 ` Yu Kuai
2022-09-02 9:42 ` Guoqing Jiang
2022-09-02 10:02 ` Yu Kuai
2022-09-02 10:16 ` Guoqing Jiang
2022-09-02 10:53 ` Yu Kuai
2022-08-29 13:15 ` [PATCH -next 3/3] md/raid10: prevent unnecessary calls to wake_up() in fast path Yu Kuai
2022-08-29 13:40 ` [PATCH -next 0/3] md/raid10: reduce lock contention for io Guoqing Jiang
2022-08-31 11:55 ` Yu Kuai
2022-08-29 13:58 ` Paul Menzel
2022-08-30 1:09 ` Yu Kuai
2022-08-31 11:59 ` Paul Menzel
2022-08-31 12:07 ` Yu Kuai
2022-08-31 18:00 ` Song Liu
2022-09-03 6:08 ` Yu Kuai
2022-09-09 14:45 ` Song Liu
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