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From: Johannes Berg <johannes@sipsolutions.net>
To: Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	 linux-um@lists.infradead.org
Cc: richard@nod.at
Subject: Re: [PATCH v5] um: Enable preemption in UML
Date: Fri, 22 Sep 2023 09:40:53 +0200	[thread overview]
Message-ID: <2de07f54b33dc060b75d982d4d8189f12e0d4c45.camel@sipsolutions.net> (raw)
In-Reply-To: <fa4069f1-e026-7672-4f71-9319cdd683a2@cambridgegreys.com>

On Fri, 2023-09-22 at 08:38 +0100, Anton Ivanov wrote:
> > 
> > I had enabled CONFIG_DEBUG_ATOMIC_SLEEP because that's actually
> > something I'd really like to have in our testing.
> > 
> > But with that issue I don't even know how we get there really. It
> > doesn't even happen every time we fork?
> > 
> > I'll dig a little bit, but did you try enabling
> > CONFIG_DEBUG_ATOMIC_SLEEP also?
> 
> Will do. I have no crashes over here so I need to trigger this one first.
> 
> Though, frankly, if it is a race in a tlb flush it may be subject to local conditions. So it will be difficult to reproduce.
> 

Yes, it might be a race in the fork handler maybe? IOW, whenever we
actually do fork, it depends on what conditions the rest is in? I'm not
sure I fully figured out right now how the fork handler is doing all
this, but I sent my mail before I could since you were discussing :)

But it shouldn't be impossible - while I don't see it for every fork, it
does happen 8 or 9 times in a very simple test that just boots, pings a
bit, and then shuts down, so ...

johannes

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  reply	other threads:[~2023-09-22  7:40 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-22  6:52 [PATCH v5] um: Enable preemption in UML anton.ivanov
2023-09-22  7:27 ` Richard Weinberger
2023-09-22  7:29   ` Anton Ivanov
2023-09-22  7:30 ` Johannes Berg
2023-09-22  7:38   ` Anton Ivanov
2023-09-22  7:40     ` Johannes Berg [this message]
2023-09-22  8:01       ` Anton Ivanov
2023-09-22  8:13         ` Johannes Berg
2023-09-22  8:40           ` Anton Ivanov
2023-09-22  8:41           ` Johannes Berg
2023-09-22  8:43             ` Johannes Berg
2023-09-22  9:04               ` Johannes Berg
2023-09-22  9:12                 ` Anton Ivanov
2023-09-22  9:06             ` Anton Ivanov
2023-09-22  9:10               ` Johannes Berg
2023-09-22  9:14                 ` Johannes Berg
2023-09-22  9:19                   ` Anton Ivanov
2023-09-22  9:51                     ` Johannes Berg
2023-09-22  9:55                       ` Johannes Berg
2023-09-22 10:55                         ` Anton Ivanov
2023-09-22 11:17                           ` Johannes Berg

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