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

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Message-ID: <ZlQSWRvZuyaY886M@localhost.localdomain>
Date: Mon, 27 May 2024 06:55:53 +0200
From: Oscar Salvador <osalvador@...e.de>
To: Christophe Leroy <christophe.leroy@...roup.eu>
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-mm@...ck.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

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:

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


-- 
Oscar Salvador
SUSE Labs