linux-kernel - [PATCH] [v2] mm: make arch_has_descending_max_zone

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Message-Id: <20230415081904.969049-1-arnd@kernel.org>
Date:   Sat, 15 Apr 2023 10:18:20 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>, llvm@...ts.linux.dev,
        Vineet Gupta <vgupta@...nel.org>,
        Mike Rapoport <rppt@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH] [v2] mm: make arch_has_descending_max_zone_pfns() static

From: Arnd Bergmann <arnd@...db.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@...ts.linux.dev
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
v2: fix logic bug reported-by: kernel test robot <oliver.sang@...el.com>,
see https://lore.kernel.org/oe-lkp/202304151422.5e4d380b-oliver.sang@intel.com
---
 arch/arc/mm/init.c | 5 -----
 include/linux/mm.h | 1 -
 mm/mm_init.c       | 4 ++--
 3 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index ce4e939a7f07..2b89b6c53801 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -74,11 +74,6 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 		base, TO_MB(size), !in_use ? "Not used":"");
 }
 
-bool arch_has_descending_max_zone_pfns(void)
-{
-	return !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
-}
-
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 63acf4a598fe..75d8adce0aee 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3061,7 +3061,6 @@ extern void setup_per_cpu_pageset(void);
 extern int min_free_kbytes;
 extern int watermark_boost_factor;
 extern int watermark_scale_factor;
-extern bool arch_has_descending_max_zone_pfns(void);
 
 /* nommu.c */
 extern atomic_long_t mmap_pages_allocated;
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 35302b7bca83..7f7f9c677854 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1754,9 +1754,9 @@ static void __init free_area_init_memoryless_node(int nid)
  * Some architectures, e.g. ARC may have ZONE_HIGHMEM below ZONE_NORMAL. For
  * such cases we allow max_zone_pfn sorted in the descending order
  */
-bool __weak arch_has_descending_max_zone_pfns(void)
+static bool arch_has_descending_max_zone_pfns(void)
 {
-	return false;
+	return IS_ENABLED(CONFIG_ARC) && !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
 }
 
 /**
-- 
2.39.2