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From: Bob Pearson <rpearsonhpe@gmail.com>
To: Zhu Yanjun <yanjun.zhu@linux.dev>, Jason Gunthorpe <jgg@ziepe.ca>,
	Bart Van Assche <bvanassche@acm.org>
Cc: "Daisuke Matsuda (Fujitsu)" <matsuda-daisuke@fujitsu.com>,
	Leon Romanovsky <leon@kernel.org>,
	"zyjzyj2000@gmail.com" <zyjzyj2000@gmail.com>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"shinichiro.kawasaki@wdc.com" <shinichiro.kawasaki@wdc.com>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	Zhu Yanjun <yanjun.zhu@intel.com>
Subject: Re: [PATCH 1/1] Revert "RDMA/rxe: Add workqueue support for rxe tasks"
Date: Thu, 12 Oct 2023 10:38:39 -0500	[thread overview]
Message-ID: <b3a8d1f8-512c-4520-8841-06d54f483f4f@gmail.com> (raw)
In-Reply-To: <fe0fbdd9-93a2-4478-b1ef-9b2420c0d76e@linux.dev>

On 10/12/23 06:49, Zhu Yanjun wrote:
> 在 2023/10/12 7:12, Jason Gunthorpe 写道:
>> On Wed, Oct 11, 2023 at 01:14:16PM -0700, Bart Van Assche wrote:
>>> On 10/11/23 08:51, Jason Gunthorpe wrote:
>>>> If we revert it then rxe will probably just stop development
>>>> entirely. Daisuke's ODP work will be blocked and if Bob was able to
>>>> fix it he would have done so already. Which mean's Bobs ongoing work
>>>> is lost too.
>>>
>>> If Daisuke's work depends on the RXE changes then Daisuke may decide
>>> to help with the RXE changes.
>>>
>>> Introducing regressions while refactoring code is not acceptable.
>>
>> Generally, but I don't view rxe as a production part of the kernel so
>> I prefer to give time to resolve it.
>>
>>> I don't have enough spare time to help with the RXE driver.
> 
> commit 11ab7cc7ee32d6c3e16ac74c34c4bbdbf8f99292
> Author: Bart Van Assche <bvanassche@acm.org>
> Date:   Tue Aug 22 09:57:07 2023 -0700
> 
>     Change the default RDMA driver from rdma_rxe to siw
> 
>     Since the siw driver is more stable than the rdma_rxe driver, change the
>     default into siw. See e.g.
> 
> https://lore.kernel.org/all/c3d1a966-b9b0-d015-38ec-86270b5045fc@acm.org/.
> 
>     Signed-off-by: Bart Van Assche <bvanassche@acm.org>
>     Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> 
> 
>>
>> Nor I
>>
>> Jason
> 
All,

I have spent the past several weeks working on trying to resolve this issue. The one thing I can say
for sure is that the failures or their rates are very sensitive to small timing changes. I totally agree
Jason that the bug has always been there and most of the suggested changes are just masking or unmasking
it. I have been running under all the kernel lock checking I can set and have not seen any warnings
so I doubt the error is a deadlock. My suspicion remains that the root cause of the hang is loss of
a completion or a timeout before a late completion leading to the transport state machine death. There
are surely other bugs in the driver and they may show up in parallel with this hang. I see the hang
consistently from 1-2% to 30-40% of the time when running srp/002 depending on various changes I have
tried but I have not been able to reproduce the KASAN bug yet. Because the hang is easy to reproduce
I have focused on that.

Bob

      reply	other threads:[~2023-10-12 15:38 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-22 16:32 [PATCH 1/1] Revert "RDMA/rxe: Add workqueue support for rxe tasks" Zhu Yanjun
2023-09-22 16:42 ` Bart Van Assche
2023-09-26  9:43   ` Leon Romanovsky
2023-09-26  9:43 ` Leon Romanovsky
2023-09-26 14:06   ` Leon Romanovsky
2023-09-26 17:05     ` Bart Van Assche
2023-09-26 18:34       ` Bob Pearson
2023-09-26 20:24         ` Bart Van Assche
2023-09-27  0:08           ` Rain River
2023-09-27 16:36           ` Bob Pearson
2023-09-27 16:51           ` Bob Pearson
2023-10-01  6:30             ` Leon Romanovsky
2023-10-04 17:44               ` Bart Van Assche
2023-10-04  3:41           ` Zhu Yanjun
2023-10-04 17:43             ` Bart Van Assche
2023-10-04 18:38               ` Jason Gunthorpe
2023-10-05  9:25                 ` Zhu Yanjun
2023-10-05 14:21                   ` Jason Gunthorpe
2023-10-05 14:50                     ` Bart Van Assche
2023-10-05 15:56                       ` Jason Gunthorpe
2023-10-06 15:58                         ` Bob Pearson
2023-10-07  0:35                           ` Zhu Yanjun
2023-10-08 16:01                       ` Zhu Yanjun
2023-10-08 17:09                         ` Leon Romanovsky
2023-10-10  4:53                         ` Daisuke Matsuda (Fujitsu)
2023-10-10 16:09                           ` Jason Gunthorpe
2023-10-10 21:29                             ` Bart Van Assche
2023-10-11 15:51                               ` Jason Gunthorpe
2023-10-11 20:14                                 ` Bart Van Assche
2023-10-11 23:12                                   ` Jason Gunthorpe
2023-10-12 11:49                                     ` Zhu Yanjun
2023-10-12 15:38                                       ` Bob Pearson [this message]

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