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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 13 Sep 2019 09:03:46 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Anshuman Khandual <anshuman.khandual@....com>, 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



Le 13/09/2019 à 08:58, Anshuman Khandual a écrit :
> 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 ?
> 

See 
https://elixir.bootlin.com/linux/v5.3-rc8/source/include/linux/highmem.h#L91

I think it applies at least to all arches using the generic implementation.

Applies also to arm:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/mm/highmem.c#L52

Applies also to mips:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/mips/mm/highmem.c#L47

Same on sparc:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/sparc/mm/highmem.c#L52

Same on x86:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/x86/mm/highmem_32.c#L34

I have not checked others, but I guess it is like that for all.

Christophe