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i386: fix iounmap's use of vm_struct's size field

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get_vm_area always returns an area with an adjacent guard page.  That guard
page is included in vm_struct.size.  iounmap uses vm_struct.size to
determine how much address space needs to have change_page_attr applied to
it, which will BUG if applied to the guard page.

This patch adds a helper function - get_vm_area_size() in linux/vmalloc.h -
to return the actual size of a vm area, and uses it to make iounmap do the
right thing.  There are probably other places which should be using
get_vm_area_size().

Thanks to Dave Young <hidave.darkstar@gmail.com> for debugging the
problem.

[ Andi, it wasn't clear to me whether x86_64 needs the same fix. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jeremy Fitzhardinge 2007-07-21 17:11:35 +02:00 committed by Linus Torvalds
parent a2900975ef
commit 9585116ba0
2 changed files with 8 additions and 1 deletions
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2
arch/i386/mm/ioremap.c
View File

@ -196,7 +196,7 @@ void iounmap(volatile void __iomem *addr)
/* Reset the direct mapping. Can block */
if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
change_page_attr(virt_to_page(__va(p->phys_addr)),
p->size >> PAGE_SHIFT,
get_vm_area_size(p) >> PAGE_SHIFT,
PAGE_KERNEL);
global_flush_tlb();
}

7
include/linux/vmalloc.h
View File

@ -58,6 +58,13 @@ void vmalloc_sync_all(void);
/*
* Lowlevel-APIs (not for driver use!)
*/
static inline size_t get_vm_area_size(const struct vm_struct *area)
{
/* return actual size without guard page */
return area->size - PAGE_SIZE;
}
extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
extern struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end);