From: Andrey Konovalov <andreyknvl@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will.deacon@arm.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Peter Collingbourne <pcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Christoph Hellwig <hch@infradead.org>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
David Hildenbrand <david@redhat.com>,
George Kennedy <george.kennedy@oracle.com>,
Konrad Rzeszutek Wilk <konrad@darnok.org>
Subject: Re: [PATCH RESEND] mm, kasan: don't poison boot memory
Date: Thu, 18 Feb 2021 21:24:49 +0100 [thread overview]
Message-ID: <CAAeHK+z-Vsuombjed8OYYpFoL4rENpf1J5F3AzQF8+LsqjDHUg@mail.gmail.com> (raw)
In-Reply-To: <20210218104626.GA12761@arm.com>
On Thu, Feb 18, 2021 at 11:46 AM Catalin Marinas
<catalin.marinas@arm.com> wrote:
>
> The approach looks fine to me. If you don't like the trade-off, I think
> you could still leave the kasan poisoning in if CONFIG_DEBUG_KERNEL.
This won't work, Android enables CONFIG_DEBUG_KERNEL in GKI as it turns out :)
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>
> Just curious, have you noticed any issue booting a KASAN_SW_TAGS-enabled
> kernel on a system with sufficiently large RAM? Is the boot slow-down
> significant?
When booting KASAN_SW_TAGS in QEMU with 40G there's a noticeable
start-up delay compared to 2G, but it doesn't seem to be caused by
this memblock->page_alloc poisoning, as removing it makes no
noticeable difference.
I also don't see a noticeable "hang" when booting KASAN_SW_TAGS in
FVP, compared to the one I see with KASAN_HW_TAGS. But I do see a
"hang" in QEMU when going from 2G to 40G with KASAN_HW_TAGS.
It seems that doing STG is much more expensive than writing to the
shadow memory.
> For MTE, we could look at optimising the poisoning code for page size to
> use STGM or DC GZVA but I don't think we can make it unnoticeable for
> large systems (especially with DC GZVA, that's like zeroing the whole
> RAM at boot).
https://bugzilla.kernel.org/show_bug.cgi?id=211817
next prev parent reply other threads:[~2021-02-18 20:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 20:59 [PATCH RESEND] mm, kasan: don't poison boot memory Andrey Konovalov
2021-02-18 10:46 ` Catalin Marinas
2021-02-18 20:24 ` Andrey Konovalov [this message]
2021-02-19 16:35 ` Catalin Marinas
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