linux-kernel - Re: [PATCH v2 00/12] mm/kasan: make kasan=on|off work for all three modes

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Message-ID: <aJtZTLPtHUfUsiuQ@MiWiFi-R3L-srv>
Date: Tue, 12 Aug 2025 23:10:04 +0800
From: Baoquan He <bhe@...hat.com>
To: linux-mm@...ck.org
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
	dvyukov@...gle.com, vincenzo.frascino@....com,
	akpm@...ux-foundation.org, kasan-dev@...glegroups.com,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	sj@...nel.org, lorenzo.stoakes@...cle.com, elver@...gle.com,
	snovitoll@...il.com
Subject: Re: [PATCH v2 00/12] mm/kasan: make kasan=on|off work for all three
 modes

On 08/12/25 at 08:49pm, Baoquan He wrote:
> Currently only hw_tags mode of kasan can be enabled or disabled with
> kernel parameter kasan=on|off for built kernel. For kasan generic and
> sw_tags mode, there's no way to disable them once kernel is built.
> This is not convenient sometime, e.g in system kdump is configured.
> When the 1st kernel has KASAN enabled and crash triggered to switch to
> kdump kernel, the generic or sw_tags mode will cost much extra memory
> for kasan shadow while in fact it's meaningless to have kasan in kdump
> kernel.
> 
> So this patchset moves the kasan=on|off out of hw_tags scope and into
> common code to make it visible in generic and sw_tags mode too. Then we
> can add kasan=off in kdump kernel to reduce the unneeded meomry cost for
> kasan.
> 
> Changelog:
> ====
> v1->v2:
> - Add __ro_after_init for __ro_after_init, and remove redundant blank
                            ~~~~~~~~~~~~~ s/__ro_after_init/kasan_arg_disabled/
                            Sorry for typo here.
>   lines in mm/kasan/common.c. Thanks to Marco.