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From: Timothy Pearson <tpearson@raptorengineering.com>
To: Timothy Pearson <tpearson@raptorengineering.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	regressions <regressions@lists.linux.dev>,
	 Pavel Begunkov <asml.silence@gmail.com>
Subject: Re: Regression in io_uring, leading to data corruption
Date: Mon, 13 Nov 2023 23:06:44 -0600 (CST)	[thread overview]
Message-ID: <1357741503.47170425.1699938404661.JavaMail.zimbra@raptorengineeringinc.com> (raw)
In-Reply-To: <1270025902.47126081.1699923171139.JavaMail.zimbra@raptorengineeringinc.com>



----- Original Message -----
> From: "Timothy Pearson" <tpearson@raptorengineering.com>
> To: "Jens Axboe" <axboe@kernel.dk>
> Cc: "regressions" <regressions@lists.linux.dev>, "Pavel Begunkov" <asml.silence@gmail.com>
> Sent: Monday, November 13, 2023 6:52:51 PM
> Subject: Re: Regression in io_uring, leading to data corruption
> 
> Seemed to do what I wanted, however corruption remains.  Was worth a try...
> 
> I guess I'll proceed under the assumption that somehow the thread setup is
> stomping on userspace for now.

Finally found it!  Patch here:

https://lore.kernel.org/regressions/19221908.47168775.1699937769845.JavaMail.zimbra@raptorengineeringinc.com/T/#u

We were missing the appropriate barrier instruction inside the IPI issued by the task_work_add() call, which was in turn issued during queued io worker creation.  The explaination for how userspace was getting corrupted boils down to an inconsistent view of main memory as seen the two cores involved in the worker handoff and new worker creation.

Who doesn't love a one line fix after a week and a half of pulling one's hair out? ;)

  reply	other threads:[~2023-11-14  5:06 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-07 16:34 Regression in io_uring, leading to data corruption Timothy Pearson
2023-11-07 16:49 ` Jens Axboe
2023-11-07 16:57   ` Timothy Pearson
2023-11-07 17:14     ` Jens Axboe
2023-11-07 21:22 ` Jens Axboe
2023-11-07 21:39   ` Timothy Pearson
2023-11-07 21:46     ` Jens Axboe
2023-11-07 22:07       ` Timothy Pearson
2023-11-07 22:16         ` Jens Axboe
2023-11-07 22:29           ` Timothy Pearson
2023-11-07 22:44             ` Jens Axboe
2023-11-07 23:12               ` Timothy Pearson
2023-11-07 23:16                 ` Jens Axboe
2023-11-07 23:34                   ` Timothy Pearson
2023-11-07 23:52                     ` Jens Axboe
2023-11-08  0:02                       ` Timothy Pearson
2023-11-08  0:09                         ` Jens Axboe
2023-11-08  3:27                           ` Timothy Pearson
2023-11-08  3:30                             ` Timothy Pearson
2023-11-08  4:00                           ` Timothy Pearson
2023-11-08 15:10                             ` Jens Axboe
2023-11-08 15:14                               ` Jens Axboe
2023-11-08 17:10                                 ` Timothy Pearson
2023-11-08 17:26                                   ` Jens Axboe
2023-11-08 17:40                                     ` Timothy Pearson
2023-11-08 17:49                                       ` Jens Axboe
2023-11-08 17:57                                         ` Jens Axboe
2023-11-08 18:36                                           ` Timothy Pearson
2023-11-08 18:51                                             ` Timothy Pearson
2023-11-08 19:08                                               ` Jens Axboe
2023-11-08 19:06                                             ` Jens Axboe
2023-11-08 22:05                                               ` Jens Axboe
2023-11-08 22:15                                                 ` Timothy Pearson
2023-11-08 22:18                                                   ` Jens Axboe
2023-11-08 22:28                                                     ` Timothy Pearson
2023-11-08 23:58                                                     ` Jens Axboe
2023-11-09 15:12                                                       ` Jens Axboe
2023-11-09 17:00                                                         ` Timothy Pearson
2023-11-09 17:17                                                           ` Jens Axboe
2023-11-09 17:24                                                             ` Timothy Pearson
2023-11-09 17:30                                                               ` Jens Axboe
2023-11-09 17:36                                                                 ` Timothy Pearson
2023-11-09 17:38                                                                   ` Jens Axboe
2023-11-09 17:42                                                                     ` Timothy Pearson
2023-11-09 17:45                                                                       ` Jens Axboe
2023-11-09 18:20                                                                         ` tpearson
2023-11-10  3:51                                                                           ` Jens Axboe
2023-11-10  4:35                                                                             ` Timothy Pearson
2023-11-10  6:48                                                                               ` Timothy Pearson
2023-11-10 14:52                                                                                 ` Jens Axboe
2023-11-11 18:42                                                                                   ` Timothy Pearson
2023-11-11 18:58                                                                                     ` Jens Axboe
2023-11-11 19:04                                                                                       ` Timothy Pearson
2023-11-11 19:11                                                                                         ` Jens Axboe
2023-11-11 19:15                                                                                           ` Timothy Pearson
2023-11-11 19:23                                                                                             ` Jens Axboe
2023-11-11 21:57                                                                                     ` Timothy Pearson
2023-11-13 17:06                                                                                       ` Timothy Pearson
2023-11-13 17:39                                                                                         ` Jens Axboe
2023-11-13 19:02                                                                                           ` Timothy Pearson
2023-11-13 19:29                                                                                             ` Jens Axboe
2023-11-13 20:58                                                                                               ` Timothy Pearson
2023-11-13 21:22                                                                                                 ` Timothy Pearson
2023-11-13 22:15                                                                                                 ` Jens Axboe
2023-11-13 23:19                                                                                                   ` Timothy Pearson
2023-11-13 23:48                                                                                                     ` Jens Axboe
2023-11-14  0:04                                                                                                       ` Timothy Pearson
2023-11-14  0:13                                                                                                         ` Jens Axboe
2023-11-14  0:52                                                                                                           ` Timothy Pearson
2023-11-14  5:06                                                                                                             ` Timothy Pearson [this message]
2023-11-14 13:17                                                                                                               ` Jens Axboe
2023-11-14 16:59                                                                                                                 ` Timothy Pearson
2023-11-14 17:04                                                                                                                   ` Jens Axboe
2023-11-14 17:14                                                                                                                     ` Timothy Pearson
2023-11-14 17:17                                                                                                                       ` Jens Axboe
2023-11-14 17:21                                                                                                                         ` Timothy Pearson
2023-11-14 17:57                                                                                                                           ` Timothy Pearson
2023-11-14 18:02                                                                                                                             ` Jens Axboe
2023-11-14 18:12                                                                                                                               ` Timothy Pearson
2023-11-14 18:26                                                                                                                                 ` Jens Axboe
2023-11-15 11:03                                                                                                                                   ` Timothy Pearson
2023-11-15 16:46                                                                                                                                     ` Jens Axboe
2023-11-15 17:03                                                                                                                                       ` Timothy Pearson
2023-11-15 18:30                                                                                                                                         ` Jens Axboe
2023-11-15 18:35                                                                                                                                           ` Timothy Pearson
2023-11-15 18:37                                                                                                                                             ` Jens Axboe
2023-11-15 18:40                                                                                                                                               ` Timothy Pearson
2023-11-15 19:00                                                                                                                                           ` Jens Axboe
2023-11-16  3:28                                                                                                                                             ` Timothy Pearson
2023-11-16  3:46                                                                                                                                               ` Jens Axboe
2023-11-16  3:54                                                                                                                                                 ` Timothy Pearson
2023-11-19  0:16                                                                                                                                                   ` Timothy Pearson
2023-11-13 20:47                                                                                         ` Jens Axboe
2023-11-13 21:08                                                                                           ` Timothy Pearson
2023-11-10 14:48                                                                               ` Jens Axboe

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