linux-kernel - Re: [PATCH V2 2/2] mm/pgtable/debug: Add test validating architecture page table helpers

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Date:   Fri, 13 Sep 2019 12:13:05 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Christophe Leroy <christophe.leroy@....fr>, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Dan Williams <dan.j.williams@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>,
        Steven Price <Steven.Price@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Kees Cook <keescook@...omium.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Matthew Wilcox <willy@...radead.org>,
        Sri Krishna chowdary <schowdary@...dia.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Vineet Gupta <vgupta@...opsys.com>,
        James Hogan <jhogan@...nel.org>,
        Paul Burton <paul.burton@...s.com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        linux-snps-arc@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] mm/pgtable/debug: Add test validating
 architecture page table helpers

On Fri, Sep 13, 2019 at 02:32:04PM +0530, Anshuman Khandual wrote:
> 
> On 09/12/2019 10:44 PM, Christophe Leroy wrote:
> > 
> > 
> > Le 12/09/2019 à 08:02, Anshuman Khandual a écrit :
> >> 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.
> >>
> >> Test page table and memory pages creating it's entries at various level are
> >> all allocated from system memory with required alignments. If memory pages
> >> with required size and alignment could not be allocated, then all depending
> >> individual tests are skipped.
> >>
> > 
> > [...]
> > 
> >>
> >> Suggested-by: Catalin Marinas <catalin.marinas@....com>
> >> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> >> ---
> >>   arch/x86/include/asm/pgtable_64_types.h |   2 +
> >>   mm/Kconfig.debug                        |  14 +
> >>   mm/Makefile                             |   1 +
> >>   mm/arch_pgtable_test.c                  | 429 ++++++++++++++++++++++++
> >>   4 files changed, 446 insertions(+)
> >>   create mode 100644 mm/arch_pgtable_test.c
> >>
> >> diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
> >> index 52e5f5f2240d..b882792a3999 100644
> >> --- a/arch/x86/include/asm/pgtable_64_types.h
> >> +++ b/arch/x86/include/asm/pgtable_64_types.h
> >> @@ -40,6 +40,8 @@ static inline bool pgtable_l5_enabled(void)
> >>   #define pgtable_l5_enabled() 0
> >>   #endif /* CONFIG_X86_5LEVEL */
> >>   +#define mm_p4d_folded(mm) (!pgtable_l5_enabled())
> >> +
> > 
> > This is specific to x86, should go in a separate patch.
> 
> Thought about it but its just a single line. Kirill suggested this in the
> previous version. There is a generic fallback definition but s390 has it's
> own. This change overrides the generic one for x86 probably as a fix or as
> an improvement. Kirill should be able to help classify it in which case it
> can be a separate patch.

I don't think it worth a separate patch.

-- 
 Kirill A. Shutemov