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Date:   Tue, 18 Apr 2023 14:36:42 +0200 (CEST)
From:   Geert Uytterhoeven <geert@linux-m68k.org>
To:     Arnd Bergmann <arnd@kernel.org>
cc:     Andrew Morton <akpm@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>, llvm@lists.linux.dev,
        Vineet Gupta <vgupta@kernel.org>,
        Mike Rapoport <rppt@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        "Liam R. Howlett" <Liam.Howlett@Oracle.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Biju Das <biju.das.jz@bp.renesas.com>,
        linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH] [v2] mm: make arch_has_descending_max_zone_pfns()
 static
In-Reply-To: <20230415081904.969049-1-arnd@kernel.org>
Message-ID: <cab7df5e-a7d7-ce15-20fa-31afe6f7180@linux-m68k.org>
References: <20230415081904.969049-1-arnd@kernel.org>
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 	Hi Arnd,

On Sat, 15 Apr 2023, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> clang produces a build failure on x86 for some randconfig builds
> after a change that moves around code to mm/mm_init.c:
>
> Cannot find symbol for section 2: .text.
> mm/mm_init.o: failed
>
> I have not been able to figure out why this happens, but the __weak
> annotation on arch_has_descending_max_zone_pfns() is the trigger here.
>
> Removing the weak function in favor of an open-coded Kconfig option
> check avoids the problem and becomes clearer as well as better to
> optimize by the compiler.
>
> Fixes: 9420f89db2dd ("mm: move most of core MM initialization to mm/mm_init.c")
> Cc: llvm@lists.linux.dev
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: fix logic bug reported-by: kernel test robot <oliver.sang@intel.com>,
> see https://lore.kernel.org/oe-lkp/202304151422.5e4d380b-oliver.sang@intel.com

Thanks, reverting commit 413d478d3b366d09 ("mm: make
arch_has_descending_max_zone_pfns() static") in next-20230417 and
applying your v2 makes Salvator-XS regain its DMA memory zone.

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds