linux-kernel - Re: Occasional hung with UM after enable VMAP

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Message-ID: <94613ccb-ab4d-851d-01d0-dfa72b73fdb0@kot-begemot.co.uk>
Date:   Tue, 4 Jan 2022 21:39:15 +0000
From:   Anton Ivanov <anton.ivanov@...-begemot.co.uk>
To:     Walter Lozano <walter.lozano@...labora.com>,
        Johannes Berg <johannes@...solutions.net>,
        linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Sjoerd Simons <sjoerd.simons@...labora.com>,
        ritesh sarraf <ritesh.sarraf@...labora.com>
Subject: Re: Occasional hung with UM after enable VMAP_STACK

On 04/01/2022 19:26, Walter Lozano wrote:
> Hi Johannes,
> 
> On 1/4/22 16:04, Johannes Berg wrote:
>> On Tue, 2022-01-04 at 15:10 -0300, Walter Lozano wrote:
>>> Hi all,
>>>
>>> I noticed that after "um: enable VMAP_STACK" [1] I experienced some
>>> occasional hung in my Gitlab CI jobs that use user-mode-linux to build
>>> distro images.
>>>
>> Did you actually *enable* VMAP_STACK in the config as well? The commit
>> just makes it *possible* to enable it, you still have to set it
>> yourself. So you should be able to easily check with/without that
>> setting.
> 
> Thank you for your quick response. The Debian configuration on package 
> user-mode-linux have these settings
> 
> CONFIG_HAVE_ARCH_VMAP_STACK=y
> CONFIG_VMAP_STACK=y
> 
> 
> as you can see in [1]. I did run some tests disabling those settings, 
> which passed without any hung.
> 
> Unfortunately the "occasional" behavior makes this issue a bit tricky to 
> debug.
> 
> Regards,
> 
> Walter
> 
> [1] 
> https://salsa.debian.org/uml-team/user-mode-linux/-/blob/master/config.amd64#L321 
> 
> 

Just to narrow things down - 64 bit or 32 bit?

-- 
Anton R. Ivanov
https://www.kot-begemot.co.uk/