linux-kernel - Re: [PATCH 0/2] um: improve UML page fault handling

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Message-ID: <435201914.200552.1704410531143.JavaMail.zimbra@nod.at>
Date: Fri, 5 Jan 2024 00:22:11 +0100 (CET)
From: Richard Weinberger <richard@....at>
To: Petr Tesarik <petrtesarik@...weicloud.com>
Cc: anton ivanov <anton.ivanov@...bridgegreys.com>, 
	Johannes Berg <johannes@...solutions.net>, 
	linux-um <linux-um@...ts.infradead.org>, 
	linux-kernel <linux-kernel@...r.kernel.org>, 
	Roberto Sassu <roberto.sassu@...weicloud.com>, petr@...arici.cz, 
	Petr Tesarik <petr.tesarik1@...wei-partners.com>
Subject: Re: [PATCH 0/2] um: improve UML page fault handling

----- Ursprüngliche Mail -----
> Von: "Petr Tesarik" <petrtesarik@...weicloud.com>
> An: "richard" <richard@....at>, "anton ivanov" <anton.ivanov@...bridgegreys.com>, "Johannes Berg"
> <johannes@...solutions.net>, "linux-um" <linux-um@...ts.infradead.org>, "linux-kernel" <linux-kernel@...r.kernel.org>
> CC: "Roberto Sassu" <roberto.sassu@...weicloud.com>, petr@...arici.cz, "Petr Tesarik"
> <petr.tesarik1@...wei-partners.com>
> Gesendet: Freitag, 15. Dezember 2023 13:14:29
> Betreff: [PATCH 0/2] um: improve UML page fault handling

> From: Petr Tesarik <petr.tesarik1@...wei-partners.com>
> 
> Improve UML handling of segmentation faults in kernel mode. Although
> such page faults are generally caused by a kernel bug, it is annoying
> if they cause an infinite loop, or panic the kernel. More importantly,
> a robust implementation allows to write KUnit tests for various guard
> pages, preventing potential kernel self-protection regressions.
> 
> Petr Tesarik (2):
>  um: do not panic on kernel mode faults
>  um: oops on accessing an non-present page in the vmalloc area

I think this is a good thing to have.
For the implementation side, this needs to use the oops_* helpers
from kernel/panic.c and taint the kernel, etc...
See arch/x86/kernel/dumpstack.c die() and friends.

Thanks,
//richard