linux-kernel - Re: [PATCH] mm, kmsan: fix infinite recursion due to RCU critical section

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Message-ID: <CAG_fn=VMTOJn+wtg0NfE2bFtuh_OY1DQeMu0KB5u4sjS05sXgw@mail.gmail.com>
Date: Thu, 18 Jan 2024 13:46:26 +0100
From: Alexander Potapenko <glider@...gle.com>
To: Charan Teja Kalla <quic_charante@...cinc.com>
Cc: Marco Elver <elver@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Dmitry Vyukov <dvyukov@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org, syzbot+93a9e8a3dea8d6085e12@...kaller.appspotmail.com
Subject: Re: [PATCH] mm, kmsan: fix infinite recursion due to RCU critical section

On Thu, Jan 18, 2024 at 12:28 PM Charan Teja Kalla
<quic_charante@...cinc.com> wrote:
>
> May I ask if KMSAN also instruments the access to the memory managed as
> ZONE_DEVICE. You know this is not the RAM and also these pages will
> never be onlined thus also not be available in buddy.

Is there a way to tell whether a memory chunk belongs to ZONE_DEVICE
by its address?
Won't such check involve calling pfn_valid() or a similar function
that would also require synchronization?

In general, if e.g. one can call memset() on ZONE_DEVICE memory, it is
already going to be instrumented by KMSAN.