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SubjectRe: [PATCH] kernel parameter vmalloc size fix

* Dave Young <hidave.darkstar@gmail.com> wrote:

> I do some test about this last weekend, there's some questions, could
> you help to fix it?
>
> 1. MAXMEM :
> (-__PAGE_OFFSET - __VMALLOC_RESERVE).
> The space after VMALLOC_END is included as well, seting it to
> (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE), is it right?
>
> 2. VMALLOC_OFFSET is not considered in __VMALLOC_RESERVE
> Should 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.
> Set it to ((unsigned long)high_memory + VMALLOC_OFFSET), is it right?
>
> Attached the proposed patch. please give some advice.

i've ported it to tip/master, see the patch below. Yinghai, what do you
think about this change?

Ingo

---
arch/x86/mm/pgtable_32.c | 3 ++-
include/asm-x86/page_32.h | 1 -
include/asm-x86/pgtable_32.h | 5 +++--
3 files changed, 5 insertions(+), 4 deletions(-)

Index: tip/arch/x86/mm/pgtable_32.c
===================================================================
--- tip.orig/arch/x86/mm/pgtable_32.c
+++ tip/arch/x86/mm/pgtable_32.c
@@ -171,7 +171,8 @@ static int __init parse_vmalloc(char *ar
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);
Index: tip/include/asm-x86/page_32.h
===================================================================
--- tip.orig/include/asm-x86/page_32.h
+++ tip/include/asm-x86/page_32.h
@@ -95,7 +95,6 @@ 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,
Index: tip/include/asm-x86/pgtable_32.h
===================================================================
--- tip.orig/include/asm-x86/pgtable_32.h
+++ tip/include/asm-x86/pgtable_32.h
@@ -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


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