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From: Marco Elver <elver@google.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Russell King <linux@armlinux.org.uk>,
	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,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 0/4] ARM: Support KFENCE feature
Date: Wed, 25 Aug 2021 12:57:22 +0200	[thread overview]
Message-ID: <YSYiEgEcW1Ln3+9P@elver.google.com> (raw)
In-Reply-To: <CANpmjNMnU5P9xsDhgeBKQR7Tg-3cHPkMNx7906yYwEAj85sNWg@mail.gmail.com>

On Wed, Aug 25, 2021 at 12:14PM +0200, Marco Elver wrote:
> On Wed, 25 Aug 2021 at 11:17, Kefeng Wang <wangkefeng.wang@huawei.com> wrote:
> > The patch 1~3 is to support KFENCE feature on ARM.
> >
> > NOTE:
> > The context of patch2/3 changes in arch/arm/mm/fault.c is based on link[1],
> > which make some refactor and cleanup about page fault.
> >
> > kfence_test is not useful when kfence is not enabled, skip kfence test
> > when kfence not enabled in patch4.
> >
> > I tested the kfence_test on ARM QEMU with or without ARM_LPAE and all passed.
> 
> Thank you for enabling KFENCE on ARM -- I'll leave arch-code review to
> an ARM maintainer.
> 
> However, as said on the patch, please drop the change to the
> kfence_test and associated changes. This is working as intended; while
> you claim that it takes a long time to run when disabled, when running
> manually you just should not run it when disabled. There are CI
> systems that rely on the KUnit test output and the fact that the
> various test cases say "not ok" etc. Changing that would mean such CI
> systems would no longer fail if KFENCE was accidentally disabled (once
> KFENCE is enabled on various CI, which we'd like to do at some point).
> There are ways to fail the test faster, but they all complicate the
> test for no good reason. (And the addition of a new exported function
> that is essentially useless.)

I spoke too soon -- we export __kfence_pool, and that's good enough to
fail the test fast if KFENCE was disabled at boot:

	https://lkml.kernel.org/r/20210825105533.1247922-1-elver@google.com

will do the trick. So please drop your patch 4/4 here.

Thanks,
-- Marco

  reply	other threads:[~2021-08-25 10:57 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-25  9:21 Kefeng Wang
2021-08-25  9:21 ` [PATCH 1/4] ARM: mm: Provide set_memory_valid() Kefeng Wang
2021-08-25  9:21 ` [PATCH 2/4] ARM: mm: Provide is_write_fault() Kefeng Wang
2021-08-25  9:21 ` [PATCH 3/4] ARM: Support KFENCE for ARM Kefeng Wang
2021-08-25 13:18   ` ownia
2021-08-25 14:31     ` Kefeng Wang
2021-08-25  9:21 ` [PATCH 4/4] mm: kfence: Only load kfence_test when kfence is enabled Kefeng Wang
2021-08-25  9:31   ` Alexander Potapenko
2021-08-25  9:54     ` Marco Elver
2021-08-25  9:55     ` Kefeng Wang
2021-08-25  9:59       ` Marco Elver
2021-08-25 10:14 ` [PATCH 0/4] ARM: Support KFENCE feature Marco Elver
2021-08-25 10:57   ` Marco Elver [this message]
2021-08-25 14:15     ` Kefeng Wang
2021-08-25 14:28     ` Kefeng Wang

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