From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org, kasan-dev@googlegroups.com,
        Nathan Lynch <nathanl@linux.ibm.com>
Subject: Re: [PATCH] kasan: Fix Oops due to missing calls to
 kasan_arch_is_ready()
In-Reply-To: <20230126152024.bfdd25de2ff5107fa7c02986@linux-foundation.org>
References: <150768c55722311699fdcf8f5379e8256749f47d.1674716617.git.christophe.leroy@csgroup.eu>
 <20230126152024.bfdd25de2ff5107fa7c02986@linux-foundation.org>
Date:   Fri, 27 Jan 2023 15:50:01 +1100
Message-ID: <874jsctwcm.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Andrew Morton <akpm@linux-foundation.org> writes:
> On Thu, 26 Jan 2023 08:04:47 +0100 Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
>
>> On powerpc64, you can build a kernel with KASAN as soon as you build it
>> with RADIX MMU support. However if the CPU doesn't have RADIX MMU,
>> KASAN isn't enabled at init and the following Oops is encountered.
>
> Should we backport to -stable?  If so, can we identify a suitable Fixes: target?

It would be nice if it went to stable, but I'd defer to the Kasan maintainers.

The kasan_arch_is_ready() checks went in a while back, but there wasn't
a meaningful user until the powerpc support went in, so I'd target that:

Fixes: 41b7a347bf14 ("powerpc: Book3S 64-bit outline-only KASAN support")
Cc: stable@vger.kernel.org # v5.19+

cheers