linux-kernel - [PATCH] arm64: mm: decrease the section size to reduce the memory reserved for the page map

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Date:   Fri, 4 Dec 2020 09:44:43 +0800
From:   Wei Li <liwei213@...wei.com>
To:     <catalin.marinas@....com>, <rppt@...ux.ibm.com>, <will@...nel.org>,
        <liwei213@...wei.com>
CC:     <fengbaopeng2@...ilicon.com>, <nsaenzjulienne@...e.de>,
        <steve.capper@....com>, <song.bao.hua@...ilicon.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <butao@...ilicon.com>
Subject: [PATCH] arm64: mm: decrease the section size to reduce the memory reserved for the page map

For the memory hole, sparse memory model that define SPARSEMEM_VMEMMAP
do not free the reserved memory for the page map, decrease the section
size can reduce the waste of reserved memory.

Signed-off-by: Wei Li <liwei213@...wei.com>
Signed-off-by: Baopeng Feng <fengbaopeng2@...ilicon.com>
Signed-off-by: Xia Qing <saberlily.xia@...ilicon.com>
---
 arch/arm64/include/asm/sparsemem.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/sparsemem.h b/arch/arm64/include/asm/sparsemem.h
index 1f43fcc79738..8963bd3def28 100644
--- a/arch/arm64/include/asm/sparsemem.h
+++ b/arch/arm64/include/asm/sparsemem.h
@@ -7,7 +7,7 @@

 #ifdef CONFIG_SPARSEMEM
 #define MAX_PHYSMEM_BITS	CONFIG_ARM64_PA_BITS
-#define SECTION_SIZE_BITS	30
+#define SECTION_SIZE_BITS	27
 #endif

 #endif
--
2.15.0