Commit 8745808f authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
Browse files

mm, arch: remove empty_bad_page* 

empty_bad_page() and empty_bad_pte_table() seem to be relics from old
days which is not used by any code for a long time.  I have tried to
find when exactly but this is not really all that straightforward due to
many code movements - traces disappear around 2.4 times.

Anyway no code really references neither empty_bad_page nor
empty_bad_pte_table.  We only allocate the storage which is not used by
anybody so remove them.

Link: http://lkml.kernel.org/r/20171004150045.30755-1-mhocko@kernel.org


Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarRalf Baechle <ralf@linus-mips.org>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: David Howells <dhowells@redhat.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a2e16731

arch/frv/mm/init.c

+0 −14
Original line number Diff line number Diff line
@@ -42,21 +42,9 @@ 
#undef DEBUG



/*

 * BAD_PAGE is the page that is used for page faults when linux

 * is out-of-memory. Older versions of linux just did a

 * do_exit(), but using this instead means there is less risk

 * for a process dying in kernel mode, possibly leaving a inode

 * unused etc..

 *

 * BAD_PAGETABLE is the accompanying page-table: it is initialized

 * to point to BAD_PAGE entries.

 *

 * ZERO_PAGE is a special page that is used for zero-initialized

 * data and COW.

 */

static unsigned long empty_bad_page_table;

static unsigned long empty_bad_page;



unsigned long empty_zero_page;

EXPORT_SYMBOL(empty_zero_page);
@@ -72,8 +60,6 @@ void __init paging_init(void) 
	unsigned long zones_size[MAX_NR_ZONES] = {0, };



	/* allocate some pages for kernel housekeeping tasks */

	empty_bad_page_table	= (unsigned long) alloc_bootmem_pages(PAGE_SIZE);

	empty_bad_page		= (unsigned long) alloc_bootmem_pages(PAGE_SIZE);

	empty_zero_page		= (unsigned long) alloc_bootmem_pages(PAGE_SIZE);



	memset((void *) empty_zero_page, 0, PAGE_SIZE);

arch/h8300/mm/init.c

+0 −13
Original line number Diff line number Diff line
@@ -40,20 +40,9 @@ 
#include <asm/sections.h>



/*

 * BAD_PAGE is the page that is used for page faults when linux

 * is out-of-memory. Older versions of linux just did a

 * do_exit(), but using this instead means there is less risk

 * for a process dying in kernel mode, possibly leaving a inode

 * unused etc..

 *

 * BAD_PAGETABLE is the accompanying page-table: it is initialized

 * to point to BAD_PAGE entries.

 *

 * ZERO_PAGE is a special page that is used for zero-initialized

 * data and COW.

 */

static unsigned long empty_bad_page_table;

static unsigned long empty_bad_page;

unsigned long empty_zero_page;



/*
@@ -78,8 +67,6 @@ void __init paging_init(void) 
	 * Initialize the bad page table and bad page to point

	 * to a couple of allocated pages.

	 */

	empty_bad_page_table = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);

	empty_bad_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);

	empty_zero_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);

	memset((void *)empty_zero_page, 0, PAGE_SIZE);

arch/mips/include/asm/pgtable-64.h

+1 −7
Original line number Diff line number Diff line
@@ -31,12 +31,7 @@ 
 * tables. Each page table is also a single 4K page, giving 512 (==

 * PTRS_PER_PTE) 8 byte ptes. Each pud entry is initialized to point to

 * invalid_pmd_table, each pmd entry is initialized to point to

 * invalid_pte_table, each pte is initialized to 0. When memory is low,

 * and a pmd table or a page table allocation fails, empty_bad_pmd_table

 * and empty_bad_page_table is returned back to higher layer code, so

 * that the failure is recognized later on. Linux does not seem to

 * handle these failures very well though. The empty_bad_page_table has

 * invalid pte entries in it, to force page faults.

 * invalid_pte_table, each pte is initialized to 0.

 *

 * Kernel mappings: kernel mappings are held in the swapper_pg_table.

 * The layout is identical to userspace except it's indexed with the
@@ -175,7 +170,6 @@ 
	printk("%s:%d: bad pgd %016lx.\n", __FILE__, __LINE__, pgd_val(e))



extern pte_t invalid_pte_table[PTRS_PER_PTE];

extern pte_t empty_bad_page_table[PTRS_PER_PTE];



#ifndef __PAGETABLE_PUD_FOLDED

/*

arch/mn10300/kernel/head.S

+0 −8
Original line number Diff line number Diff line
@@ -433,14 +433,6 @@ ENTRY(swapper_pg_dir) 
ENTRY(empty_zero_page)

	.space PAGE_SIZE



	.balign PAGE_SIZE

ENTRY(empty_bad_page)

	.space PAGE_SIZE



	.balign PAGE_SIZE

ENTRY(empty_bad_pte_table)

	.space PAGE_SIZE



	.balign PAGE_SIZE

ENTRY(large_page_table)

	.space PAGE_SIZE

arch/sh/kernel/head_64.S

+0 −8
Original line number Diff line number Diff line
@@ -101,14 +101,6 @@ empty_zero_page: 
mmu_pdtp_cache:

	.space PAGE_SIZE, 0



	.global empty_bad_page

empty_bad_page:

	.space PAGE_SIZE, 0



	.global empty_bad_pte_table

empty_bad_pte_table:

	.space PAGE_SIZE, 0



	.global	fpu_in_use

fpu_in_use:	.quad	0

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