Re: [PATCH] arm64: mm: decrease the section size to reduce the memory reserved for the page map
From: Will Deacon <will@kernel.org>
Date: 2020-12-04 11:14:50
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On Fri, Dec 04, 2020 at 09:44:43AM +0800, Wei Li wrote:
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Baopeng Feng <redacted> Signed-off-by: Xia Qing <redacted> --- 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
We chose '30' to avoid running out of bits in the page flags. What changed? With this patch, I can trigger: ./include/linux/mmzone.h:1170:2: error: Allocator MAX_ORDER exceeds SECTION_SIZE #error Allocator MAX_ORDER exceeds SECTION_SIZE if I bump up NR_CPUS and NODES_SHIFT. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel