From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Fri, 13 Sep 2019 06:58:36 +0000
Subject: Re: [PATCH] mm/pgtable/debug: Fix test validating architecture page table helpers
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References: <1892b37d1fd9a4ed39e76c4b999b6556077201c0.1568355752.git.christophe.leroy@c-s.fr>
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To: Christophe Leroy <christophe.leroy@c-s.fr>, linux-mm@kvack.org
Cc: Mark Rutland <mark.rutland@arm.com>, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, James Hogan <jhogan@kernel.org>, Heiko Carstens <heiko.carstens@de.ibm.com>, Michal Hocko <mhocko@kernel.org>, Dave Hansen <dave.hansen@intel.com>, Paul Mackerras <paulus@samba.org>, sparclinux@vger.kernel.org, Dan Williams <dan.j.williams@intel.com>, linux-s390@vger.kernel.org, Jason Gunthorpe <jgg@ziepe.ca>, x86@kernel.org, Russell King - ARM Linux <linux@armlinux.org.uk>, Matthew Wilcox <willy@infradead.org>, Steven Price <Steven.Price@arm.com>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Vlastimil Babka <vbabka@suse.cz>, linux-snps-arc@lists.infradead.org, Kees Cook <keescook@chromium.org>, Mark Brown <broonie@kernel.org>, "Kirill A . Shutemov" <kirill@shutemov.name>, Thomas Gleixner <tglx@linutronix.de>, Gerald Schaefer <gerald.schaefer@de.ibm.com>, linux-arm-kernel@lists.infradead.org, Sri Krishna chowdary <schowdary@nvidia.com>, Masahiro Yamada <yamada.masahiro@socionext.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, linux-mips@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>, linux-kernel@vger.kernel.org, Paul Burton <paul.burton@mips.com>, Mike Rapoport <rppt@linux.vnet.ibm.com>, Vineet Gupta <vgupta@synopsys.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "David S. Miller" <davem@davemloft.net>

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@c-s.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 ?