From: Yunseong Kim <ysk@kzalloc.com>
To: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
Yeoreum Yun <yeoreum.yun@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Marc Zyngier <maz@kernel.org>, Mark Brown <broonie@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Ard Biesheuvel <ardb@kernel.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com
Subject: Re: [PATCH] arm64: cpufeature: Don't cpu_enable_mte() when KASAN_GENERIC is active
Date: Fri, 10 Oct 2025 23:56:34 +0900 [thread overview]
Message-ID: <5b5d6f02-3161-4490-9652-e6d23e320a57@kzalloc.com> (raw)
In-Reply-To: <aOj8KsntbVPRNBKL@willie-the-truck>
Hi Will,
On 10/10/25 9:29 PM, Will Deacon wrote:
> On Thu, Oct 09, 2025 at 08:10:53AM +0900, Yunseong Kim wrote:
>> To summarize my situation, I thought the boot panic issue might be due
>> to incompatibility between MTE and KASAN Generic, so I sent this patch.
>>
>> However, it seems that the problem is related to the call path involving
>> ZERO page. Also, I am curious how it works correctly in other machine.
>>
>> On 10/9/25 7:28 AM, Yunseong Kim wrote:
>>> Hi Andrey,
>>>
>>> On 10/9/25 6:36 AM, Andrey Konovalov wrote:
>>>> On Wed, Oct 8, 2025 at 11:13 PM Yunseong Kim <ysk@kzalloc.com> wrote:
>>>>> [...]
>>>> I do not understand this. Why is Generic KASAN incompatible with MTE?
>>>
>>> My board wouldn't boot on the debian debug kernel, so I enabled
>>> earlycon=pl011,0x40d0000 and checked via the UART console.
>>>
>>>> Running Generic KASAN in the kernel while having MTE enabled (and e.g.
>>>> used in userspace) seems like a valid combination.
>>>
>>> Then it must be caused by something else. Thank you for letting me know.
>>>
>>> It seems to be occurring in the call path as follows:
>>>
>>> cpu_enable_mte()
>>> -> try_page_mte_tagging(ZERO_PAGE(0))
>>> -> VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));
>>>
>>> https://elixir.bootlin.com/linux/v6.17/source/arch/arm64/include/asm/mte.h#L83
>>
>> -> page_folio(ZERO_PAGE(0))
>> -> (struct folio *)_compound_head(ZERO_PAGE(0))
>>
>> https://elixir.bootlin.com/linux/v6.17/source/include/linux/page-flags.h#L307
>
> Do you have:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?id=f620d66af3165838bfa845dcf9f5f9b4089bf508
>
> ?
>
> Will
Oh, There was a recent patch! Thanks a lot for letting me know, Will.
The current Debian kernel is based on v6.17, so this patch isn’t applied yet.
I should also let the Debian kernel team people know in advance.
I’ll apply and test it, Thanks again, Will!
Best regards,
Yunseong
prev parent reply other threads:[~2025-10-10 14:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-08 21:04 [PATCH] arm64: cpufeature: Don't cpu_enable_mte() when KASAN_GENERIC is active Yunseong Kim
2025-10-08 21:36 ` Andrey Konovalov
2025-10-08 22:28 ` Yunseong Kim
2025-10-08 23:10 ` Yunseong Kim
2025-10-10 12:29 ` Will Deacon
2025-10-10 14:56 ` Yunseong Kim [this message]
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