From: Matthew Wilcox <willy@infradead.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mark Brown <Mark.Brown@arm.com>,
Steven Price <Steven.Price@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Kees Cook <keescook@chromium.org>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Sri Krishna chowdary <schowdary@nvidia.com>,
Dave Hansen <dave.hansen@intel.com>,
linux-arm-kernel@lists.infradead.org, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] mm/pgtable/debug: Add test validating architecture page table helpers
Date: Thu, 25 Jul 2019 07:39:21 -0700 [thread overview]
Message-ID: <20190725143920.GW363@bombadil.infradead.org> (raw)
In-Reply-To: <1564037723-26676-2-git-send-email-anshuman.khandual@arm.com>
On Thu, Jul 25, 2019 at 12:25:23PM +0530, Anshuman Khandual wrote:
> This adds a test module which will validate architecture page table helpers
> and accessors regarding compliance with generic MM semantics expectations.
> This will help various architectures in validating changes to the existing
> page table helpers or addition of new ones.
I think this is a really good idea.
> lib/Kconfig.debug | 14 +++
> lib/Makefile | 1 +
> lib/test_arch_pgtable.c | 290 ++++++++++++++++++++++++++++++++++++++++++++++++
Is this the right place for it? I worry that lib/ is going to get overloaded
with test code, and this feels more like mm/ test code.
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE
> +static void pmd_basic_tests(void)
> +{
> + pmd_t pmd;
> +
> + pmd = mk_pmd(page, prot);
But 'page' isn't necessarily PMD-aligned. I don't think we can rely on
architectures doing the right thing if asked to make a PMD for a randomly
aligned page.
How about finding the physical address of something like kernel_init(),
and using the corresponding pte/pmd/pud/p4d/pgd that encompasses that
address? It's also better to pass in the pfn/page rather than using global
variables to communicate to the test functions.
> + /*
> + * A huge page does not point to next level page table
> + * entry. Hence this must qualify as pmd_bad().
> + */
> + WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
I didn't know that rule. This is helpful because it gives us somewhere
to document all these tricksy little rules.
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +static void pud_basic_tests(void)
Is this the right ifdef?
next prev parent reply other threads:[~2019-07-25 14:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 6:55 [RFC] mm/debug: Add tests for architecture exported page table helpers Anshuman Khandual
2019-07-25 6:55 ` [RFC] mm/pgtable/debug: Add test validating architecture " Anshuman Khandual
2019-07-25 14:39 ` Matthew Wilcox [this message]
2019-07-25 21:38 ` Russell King - ARM Linux admin
2019-07-25 21:42 ` Matthew Wilcox
2019-07-25 21:58 ` Russell King - ARM Linux admin
2019-07-25 22:56 ` Matthew Wilcox
2019-07-26 4:47 ` Anshuman Khandual
2019-07-26 19:54 ` Matthew Wilcox
2019-07-29 8:32 ` Anshuman Khandual
2019-07-30 17:03 ` Matthew Wilcox
2019-08-05 4:35 ` Anshuman Khandual
2019-07-25 17:07 ` Catalin Marinas
2019-07-26 4:28 ` Anshuman Khandual
2019-07-25 21:54 ` Russell King - ARM Linux admin
2019-07-26 5:10 ` Anshuman Khandual
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