linux-kernel - Re: [RFC PATCH v3 05/16] powerpc/mm: Fix __find_linux

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Date: Mon, 27 May 2024 05:16:57 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Oscar Salvador <osalvador@...e.de>
CC: Andrew Morton <akpm@...ux-foundation.org>, Jason Gunthorpe
	<jgg@...dia.com>, Peter Xu <peterx@...hat.com>, Michael Ellerman
	<mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>, "linuxppc-dev@...ts.ozlabs.org"
	<linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [RFC PATCH v3 05/16] powerpc/mm: Fix __find_linux_pte() on 32
 bits with PMD leaf entries



Le 27/05/2024 à 06:55, Oscar Salvador a écrit :
> On Sun, May 26, 2024 at 11:22:25AM +0200, Christophe Leroy wrote:
>> Building on 32 bits with pmd_leaf() not returning always false leads
>> to the following error:
>>
>>    CC      arch/powerpc/mm/pgtable.o
>> arch/powerpc/mm/pgtable.c: In function '__find_linux_pte':
>> arch/powerpc/mm/pgtable.c:506:1: error: function may return address of local variable [-Werror=return-local-addr]
>>    506 | }
>>        | ^
>> arch/powerpc/mm/pgtable.c:394:15: note: declared here
>>    394 |         pud_t pud, *pudp;
>>        |               ^~~
>> arch/powerpc/mm/pgtable.c:394:15: note: declared here
>>
>> This is due to pmd_offset() being a no-op in that case.
>>
>> So rework it for powerpc/32 so that pXd_offset() are used on real
>> pointers and not on on-stack copies.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> 
> Maybe this could be folded into the patch that makes pmd_leaf() not returning
> always false, but no strong feelings:

I prefer to keep it separate, the patch introducing pmd_leaf() is 
already big enough.

> 
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> 
>