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i386: vmalloc size fix 

Booting kernel with vmalloc=[any size<=16m] will oops on my pc (i386/1G memory).

BUG_ON in arch/x86/mm/init_32.c triggered:
BUG_ON((unsigned long)high_memory > VMALLOC_START);

It's due to the vm area hole.

In include/asm-x86/pgtable_32.h:
#define VMALLOC_OFFSET	(8 * 1024 * 1024)
#define VMALLOC_START	(((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \
			 & ~(VMALLOC_OFFSET - 1))

There's several related point:
1. MAXMEM :
 (-__PAGE_OFFSET - __VMALLOC_RESERVE).
The space after VMALLOC_END is included as well, I set it to
(VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)

2. VMALLOC_OFFSET is not considered in __VMALLOC_RESERVE
fixed by adding VMALLOC_OFFSET to it.

3. VMALLOC_START :
 (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) & ~(VMALLOC_OFFSET - 1))
So it's not always 8M, bigger than 8M possible.
I set it to ((unsigned long)high_memory + VMALLOC_OFFSET)

4. the VMALLOC_RESERVE is an unused macro, so remove it here.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Cc: akpm@linux-foundation.org
Cc: hidave.darkstar@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dave Young 2008-08-20 16:43:03 -07:00 committed by Ingo Molnar
parent 6a55617ed5
commit e621bd1895
3 changed files with 5 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/mm/pgtable_32.c
View File

@ -123,7 +123,8 @@ static int __init parse_vmalloc(char *arg)
if (!arg)
return -EINVAL;
__VMALLOC_RESERVE = memparse(arg, &arg);
/* Add VMALLOC_OFFSET to the parsed value due to vm area guard hole*/
__VMALLOC_RESERVE = memparse(arg, &arg) + VMALLOC_OFFSET;
return 0;
}
early_param("vmalloc", parse_vmalloc);

3
include/asm-x86/page_32.h
View File

@ -89,9 +89,6 @@ extern int nx_enabled;
extern unsigned int __VMALLOC_RESERVE;
extern int sysctl_legacy_va_layout;
#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
#define MAXMEM (-__PAGE_OFFSET - __VMALLOC_RESERVE)
extern void find_low_pfn_range(void);
extern unsigned long init_memory_mapping(unsigned long start,
unsigned long end);

5
include/asm-x86/pgtable_32.h
View File

@ -56,8 +56,7 @@ void paging_init(void);
* area for the same reason. ;)
*/
#define VMALLOC_OFFSET (8 * 1024 * 1024)
#define VMALLOC_START (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \
& ~(VMALLOC_OFFSET - 1))
#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET)
#ifdef CONFIG_X86_PAE
#define LAST_PKMAP 512
#else
@ -73,6 +72,8 @@ void paging_init(void);
# define VMALLOC_END (FIXADDR_START - 2 * PAGE_SIZE)
#endif
#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)
/*
* Define this if things work differently on an i386 and an i486:
* it will (on an i486) warn about kernel memory accesses that are