linux-kernel - Re: [PATCH RFC v2 14/27] arm64: mte: Disable dynamic tag storage management if HW KASAN is enabled

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Date:   Tue, 28 Nov 2023 18:05:41 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Alexandru Elisei <alexandru.elisei@....com>
Cc:     catalin.marinas@....com, will@...nel.org, oliver.upton@...ux.dev,
        maz@...nel.org, james.morse@....com, suzuki.poulose@....com,
        yuzenghui@...wei.com, arnd@...db.de, akpm@...ux-foundation.org,
        mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, mhiramat@...nel.org,
        rppt@...nel.org, hughd@...gle.com, pcc@...gle.com,
        steven.price@....com, anshuman.khandual@....com,
        vincenzo.frascino@....com, eugenis@...gle.com, kcc@...gle.com,
        hyesoo.yu@...sung.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev,
        linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 14/27] arm64: mte: Disable dynamic tag storage
 management if HW KASAN is enabled

On 27.11.23 16:07, Alexandru Elisei wrote:
> Hi,
> 
> On Fri, Nov 24, 2023 at 08:54:12PM +0100, David Hildenbrand wrote:
>> On 19.11.23 17:57, Alexandru Elisei wrote:
>>> To be able to reserve the tag storage associated with a page requires that
>>> the tag storage page can be migrated.
>>>
>>> When HW KASAN is enabled, the kernel allocates pages, which are now tagged,
>>> in non-preemptible contexts, which can make reserving the associate tag
>>> storage impossible.
>>
>> I assume that it's the only in-kernel user that actually requires tagged
>> memory (besides for user space), correct?
> 
> Indeed, this is the case. I'll expand the commit message to be more clear about
> it.
> 

Great, thanks!

-- 
Cheers,

David / dhildenb