linux-kernel - Re: [PATCH v3 19/30] liveupdate: luo

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Message-ID: <CA+CK2bCx=kTVORq9dRE2h3Z4QQ-ggxanY2tDPRy13_ARhc+TqA@mail.gmail.com>
Date: Thu, 9 Oct 2025 08:01:13 -0400
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: Pratyush Yadav <pratyush@...nel.org>
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Subject: Re: [PATCH v3 19/30] liveupdate: luo_sysfs: add sysfs state monitoring

> > Because the window of kernel live update is short, it is difficult to statistics
> > how many times the kernel is live updated.
> >
> > Is it possible to add a variable to statistics the times that the kernel is live
> > updated?
>
> The kernel doesn't do the live update on its own. The process is driven
> and sequenced by userspace. So if you want to keep statistics, you
> should do it from your userspace (luod maybe?). I don't see any need for
> this in the kernel.
>

One use case I can think of is including information in kdump or the
backtrace warning/panic messages about how many times this machine has
been live-updated. In the past, I've seen bugs (related to memory
corruption) that occurred only after several kexecs, not on the first
one. With live updates, especially while the code is being stabilized,
I imagine we might have a similar situation. For that reason, it could
be useful to have a count in the dmesg logs showing how many times
this machine has been live-updated. While this information is also
available in userspace, it would be simpler for kernel developers
triaging these issues if everything were in one place.

Pasha