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

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Date:   Fri, 13 Sep 2019 12:28:08 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Christophe Leroy <christophe.leroy@....fr>, linux-mm@...ck.org
Cc:     Mark Rutland <mark.rutland@....com>, linux-ia64@...r.kernel.org,
        linux-sh@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        James Hogan <jhogan@...nel.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Michal Hocko <mhocko@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Paul Mackerras <paulus@...ba.org>, sparclinux@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-s390@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>,
        x86@...nel.org, Russell King - ARM Linux <linux@...linux.org.uk>,
        Matthew Wilcox <willy@...radead.org>,
        Steven Price <Steven.Price@....com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        linux-snps-arc@...ts.infradead.org,
        Kees Cook <keescook@...omium.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Mark Brown <broonie@...nel.org>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Dan Williams <dan.j.williams@...el.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        linux-arm-kernel@...ts.infradead.org,
        Sri Krishna chowdary <schowdary@...dia.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-mips@...r.kernel.org, Ralf Baechle <ralf@...ux-mips.org>,
        linux-kernel@...r.kernel.org, Paul Burton <paul.burton@...s.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Vineet Gupta <vgupta@...opsys.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev@...ts.ozlabs.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] mm/pgtable/debug: Fix test validating architecture page
 table helpers

On 09/13/2019 11:53 AM, Christophe Leroy wrote:
> Fix build failure on powerpc.
> 
> Fix preemption imbalance.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  mm/arch_pgtable_test.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/arch_pgtable_test.c b/mm/arch_pgtable_test.c
> index 8b4a92756ad8..f2b3c9ec35fa 100644
> --- a/mm/arch_pgtable_test.c
> +++ b/mm/arch_pgtable_test.c
> @@ -24,6 +24,7 @@
>  #include <linux/swap.h>
>  #include <linux/swapops.h>
>  #include <linux/sched/mm.h>
> +#include <linux/highmem.h>

This is okay.

>  #include <asm/pgalloc.h>
>  #include <asm/pgtable.h>
>  
> @@ -400,6 +401,8 @@ static int __init arch_pgtable_tests_init(void)
>  	p4d_clear_tests(p4dp);
>  	pgd_clear_tests(mm, pgdp);
>  
> +	pte_unmap(ptep);
> +

Now the preemption imbalance via pte_alloc_map() path i.e

pte_alloc_map() -> pte_offset_map() -> kmap_atomic()

Is not this very much powerpc 32 specific or this will be applicable
for all platform which uses kmap_XXX() to map high memory ?