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From: Alexander Potapenko <glider@google.com>
Date: Thu, 18 Jan 2024 13:46:26 +0100
Message-ID: <CAG_fn=VMTOJn+wtg0NfE2bFtuh_OY1DQeMu0KB5u4sjS05sXgw@mail.gmail.com>
Subject: Re: [PATCH] mm, kmsan: fix infinite recursion due to RCU critical section
To: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Marco Elver <elver@google.com>, Andrew Morton <akpm@linux-foundation.org>, 
	Dmitry Vyukov <dvyukov@google.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 
	Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, 
	"H. Peter Anvin" <hpa@zytor.com>, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, 
	linux-mm@kvack.org, syzbot+93a9e8a3dea8d6085e12@syzkaller.appspotmail.com
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On Thu, Jan 18, 2024 at 12:28=E2=80=AFPM Charan Teja Kalla
<quic_charante@quicinc.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.