Commit 36d40290 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
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alpha: switch from DISCONTIGMEM to SPARSEMEM 

Patch series "arch, mm: deprecate DISCONTIGMEM", v2.

It's been a while since DISCONTIGMEM is generally considered deprecated,
but it is still used by four architectures.  This set replaces
DISCONTIGMEM with a different way to handle holes in the memory map and
marks DISCONTIGMEM configuration as BROKEN in Kconfigs of these
architectures with the intention to completely remove it in several
releases.

While for 64-bit alpha and ia64 the switch to SPARSEMEM is quite obvious
and was a matter of moving some bits around, for smaller 32-bit arc and
m68k SPARSEMEM is not necessarily the best thing to do.

On 32-bit machines SPARSEMEM would require large sections to make section
index fit in the page flags, but larger sections mean that more memory is
wasted for unused memory map.

Besides, pfn_to_page() and page_to_pfn() become less efficient, at least
on arc.

So I've decided to generalize arm's approach for freeing of unused parts
of the memory map with FLATMEM and enable it for both arc and m68k.  The
details are in the description of patches 10 (arc) and 13 (m68k).

This patch (of 13):

Enable SPARSEMEM support on alpha and deprecate DISCONTIGMEM.

The required changes are mostly around moving duplicated definitions of
page access and address conversion macros to a common place and making sure
they are available for all memory models.

The DISCONTINGMEM support is marked as BROKEN an will be removed in a
couple of releases.

Link: https://lkml.kernel.org/r/20201101170454.9567-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20201101170454.9567-2-rppt@kernel.org


Signed-off-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Meelis Roos <mroos@linux.ee>
Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6d5a88cd

arch/alpha/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ config ALPHA 
	select CPU_NO_EFFICIENT_FFS if !ALPHA_EV67

	select MMU_GATHER_NO_RANGE

	select SET_FS

	select SPARSEMEM_EXTREME if SPARSEMEM

	help

	  The Alpha is a 64-bit general-purpose processor designed and

	  marketed by the Digital Equipment Corporation of blessed memory,
@@ -551,12 +552,19 @@ config NR_CPUS 


config ARCH_DISCONTIGMEM_ENABLE

	bool "Discontiguous Memory Support"

	depends on BROKEN

	help

	  Say Y to support efficient handling of discontiguous physical memory,

	  for architectures which are either NUMA (Non-Uniform Memory Access)

	  or have huge holes in the physical address space for other reasons.

	  See <file:Documentation/vm/numa.rst> for more.



config ARCH_SPARSEMEM_ENABLE

	bool "Sparse Memory Support"

	help

	  Say Y to support efficient handling of discontiguous physical memory,

	  for systems that have huge holes in the physical address space.



config NUMA

	bool "NUMA Support (EXPERIMENTAL)"

	depends on DISCONTIGMEM && BROKEN

arch/alpha/include/asm/mmzone.h

+2 −12
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ 
#ifndef _ASM_MMZONE_H_

#define _ASM_MMZONE_H_



#ifdef CONFIG_DISCONTIGMEM



#include <asm/smp.h>



/*
@@ -45,8 +47,6 @@ PLAT_NODE_DATA_LOCALNR(unsigned long p, int n) 
}

#endif



#ifdef CONFIG_DISCONTIGMEM



/*

 * Following are macros that each numa implementation must define.

 */
@@ -68,11 +68,6 @@ PLAT_NODE_DATA_LOCALNR(unsigned long p, int n) 
/* XXX: FIXME -- nyc */

#define kern_addr_valid(kaddr)	(0)



#define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)



#define pmd_page(pmd)		(pfn_to_page(pmd_val(pmd) >> 32))

#define pte_pfn(pte)		(pte_val(pte) >> 32)



#define mk_pte(page, pgprot)						     \

({								 	     \

	pte_t pte;                                                           \
@@ -95,16 +90,11 @@ PLAT_NODE_DATA_LOCALNR(unsigned long p, int n) 
	__xx;                                                           \

})



#define page_to_pa(page)						\

	(page_to_pfn(page) << PAGE_SHIFT)



#define pfn_to_nid(pfn)		pa_to_nid(((u64)(pfn) << PAGE_SHIFT))

#define pfn_valid(pfn)							\

	(((pfn) - node_start_pfn(pfn_to_nid(pfn))) <			\

	 node_spanned_pages(pfn_to_nid(pfn)))					\



#define virt_addr_valid(kaddr)	pfn_valid((__pa(kaddr) >> PAGE_SHIFT))



#endif /* CONFIG_DISCONTIGMEM */



#endif /* _ASM_MMZONE_H_ */

arch/alpha/include/asm/page.h

+4 −3
Original line number Diff line number Diff line
@@ -83,12 +83,13 @@ typedef struct page *pgtable_t; 


#define __pa(x)			((unsigned long) (x) - PAGE_OFFSET)

#define __va(x)			((void *)((unsigned long) (x) + PAGE_OFFSET))

#ifndef CONFIG_DISCONTIGMEM



#define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)

#define virt_addr_valid(kaddr)	pfn_valid((__pa(kaddr) >> PAGE_SHIFT))



#ifdef CONFIG_FLATMEM

#define pfn_valid(pfn)		((pfn) < max_mapnr)

#define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)

#endif /* CONFIG_DISCONTIGMEM */

#endif /* CONFIG_FLATMEM */



#include <asm-generic/memory_model.h>

#include <asm-generic/getorder.h>

arch/alpha/include/asm/pgtable.h

+5 −7
Original line number Diff line number Diff line
@@ -203,10 +203,10 @@ extern unsigned long __zero_page(void); 
 * Conversion functions:  convert a page and protection to a page entry,

 * and a page entry and page directory to the page they refer to.

 */

#ifndef CONFIG_DISCONTIGMEM

#define page_to_pa(page)	(((page) - mem_map) << PAGE_SHIFT)



#define page_to_pa(page)	(page_to_pfn(page) << PAGE_SHIFT)

#define pte_pfn(pte)	(pte_val(pte) >> 32)



#ifndef CONFIG_DISCONTIGMEM

#define pte_page(pte)	pfn_to_page(pte_pfn(pte))

#define mk_pte(page, pgprot)						\

({									\
@@ -236,10 +236,8 @@ pmd_page_vaddr(pmd_t pmd) 
	return ((pmd_val(pmd) & _PFN_MASK) >> (32-PAGE_SHIFT)) + PAGE_OFFSET;

}



#ifndef CONFIG_DISCONTIGMEM

#define pmd_page(pmd)	(mem_map + ((pmd_val(pmd) & _PFN_MASK) >> 32))

#define pud_page(pud)	(mem_map + ((pud_val(pud) & _PFN_MASK) >> 32))

#endif

#define pmd_page(pmd)	(pfn_to_page(pmd_val(pmd) >> 32))

#define pud_page(pud)	(pfn_to_page(pud_val(pud) >> 32))



extern inline unsigned long pud_page_vaddr(pud_t pgd)

{ return PAGE_OFFSET + ((pud_val(pgd) & _PFN_MASK) >> (32-PAGE_SHIFT)); }

arch/alpha/include/asm/sparsemem.h

0 → 100644
+18 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_ALPHA_SPARSEMEM_H

#define _ASM_ALPHA_SPARSEMEM_H



#ifdef CONFIG_SPARSEMEM



#define SECTION_SIZE_BITS	27



/*

 * According to "Alpha Architecture Reference Manual" physical

 * addresses are at most 48 bits.

 * https://download.majix.org/dec/alpha_arch_ref.pdf

 */

#define MAX_PHYSMEM_BITS	48



#endif /* CONFIG_SPARSEMEM */



#endif /* _ASM_ALPHA_SPARSEMEM_H */