linux-kernel - Re: [PATCH v2 3/9] arc: remove support for DISCONTIGMEM

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Date:   Fri, 4 Jun 2021 14:07:39 +0000
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Jonathan Corbet <corbet@....net>,
        Matt Turner <mattst88@...il.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Richard Henderson <rth@...ddle.net>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-m68k@...ts.linux-m68k.org" <linux-m68k@...ts.linux-m68k.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>,
        "linux-xtensa@...ux-xtensa.org" <linux-xtensa@...ux-xtensa.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>
Subject: Re: [PATCH v2 3/9] arc: remove support for DISCONTIGMEM

On 6/3/21 11:49 PM, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
>
> DISCONTIGMEM was replaced by FLATMEM with freeing of the unused memory map
> in v5.11.
>
> Remove the support for DISCONTIGMEM entirely.
>
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>

Looks non intrusive, but I'd still like to give this a spin on hardware 
- considering highmem on ARC has tendency to go sideways ;-)
Can you please share a branch !

Acked-by: Vineet Gupta <vgupta@...opsys.com>

Thx,
-Vineet

> ---
>   arch/arc/Kconfig              | 13 ------------
>   arch/arc/include/asm/mmzone.h | 40 -----------------------------------
>   arch/arc/mm/init.c            |  8 -------
>   3 files changed, 61 deletions(-)
>   delete mode 100644 arch/arc/include/asm/mmzone.h
>
> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
> index 2d98501c0897..d8f51eb8963b 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -62,10 +62,6 @@ config SCHED_OMIT_FRAME_POINTER
>   config GENERIC_CSUM
>   	def_bool y
>   
> -config ARCH_DISCONTIGMEM_ENABLE
> -	def_bool n
> -	depends on BROKEN
> -
>   config ARCH_FLATMEM_ENABLE
>   	def_bool y
>   
> @@ -344,15 +340,6 @@ config ARC_HUGEPAGE_16M
>   
>   endchoice
>   
> -config NODES_SHIFT
> -	int "Maximum NUMA Nodes (as a power of 2)"
> -	default "0" if !DISCONTIGMEM
> -	default "1" if DISCONTIGMEM
> -	depends on NEED_MULTIPLE_NODES
> -	help
> -	  Accessing memory beyond 1GB (with or w/o PAE) requires 2 memory
> -	  zones.
> -
>   config ARC_COMPACT_IRQ_LEVELS
>   	depends on ISA_ARCOMPACT
>   	bool "Setup Timer IRQ as high Priority"
> diff --git a/arch/arc/include/asm/mmzone.h b/arch/arc/include/asm/mmzone.h
> deleted file mode 100644
> index b86b9d1e54dc..000000000000
> --- a/arch/arc/include/asm/mmzone.h
> +++ /dev/null
> @@ -1,40 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0-only */
> -/*
> - * Copyright (C) 2016 Synopsys, Inc. (www.synopsys.com)
> - */
> -
> -#ifndef _ASM_ARC_MMZONE_H
> -#define _ASM_ARC_MMZONE_H
> -
> -#ifdef CONFIG_DISCONTIGMEM
> -
> -extern struct pglist_data node_data[];
> -#define NODE_DATA(nid) (&node_data[nid])
> -
> -static inline int pfn_to_nid(unsigned long pfn)
> -{
> -	int is_end_low = 1;
> -
> -	if (IS_ENABLED(CONFIG_ARC_HAS_PAE40))
> -		is_end_low = pfn <= virt_to_pfn(0xFFFFFFFFUL);
> -
> -	/*
> -	 * node 0: lowmem:             0x8000_0000   to 0xFFFF_FFFF
> -	 * node 1: HIGHMEM w/o  PAE40: 0x0           to 0x7FFF_FFFF
> -	 *         HIGHMEM with PAE40: 0x1_0000_0000 to ...
> -	 */
> -	if (pfn >= ARCH_PFN_OFFSET && is_end_low)
> -		return 0;
> -
> -	return 1;
> -}
> -
> -static inline int pfn_valid(unsigned long pfn)
> -{
> -	int nid = pfn_to_nid(pfn);
> -
> -	return (pfn <= node_end_pfn(nid));
> -}
> -#endif /* CONFIG_DISCONTIGMEM  */
> -
> -#endif
> diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
> index 397a201adfe3..abfeef7bf6f8 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -32,11 +32,6 @@ unsigned long arch_pfn_offset;
>   EXPORT_SYMBOL(arch_pfn_offset);
>   #endif
>   
> -#ifdef CONFIG_DISCONTIGMEM
> -struct pglist_data node_data[MAX_NUMNODES] __read_mostly;
> -EXPORT_SYMBOL(node_data);
> -#endif
> -
>   long __init arc_get_mem_sz(void)
>   {
>   	return low_mem_sz;
> @@ -147,9 +142,6 @@ void __init setup_arch_memory(void)
>   	 * to the hole is freed and ARC specific version of pfn_valid()
>   	 * handles the hole in the memory map.
>   	 */
> -#ifdef CONFIG_DISCONTIGMEM
> -	node_set_online(1);
> -#endif
>   
>   	min_high_pfn = PFN_DOWN(high_mem_start);
>   	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);