Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9585116ba09f1d8c52d0a1346e20bb9d443e9c02
Commit:     9585116ba09f1d8c52d0a1346e20bb9d443e9c02
Parent:     a2900975ef3f1df33c83e750cc1e490de3374ca8
Author:     Jeremy Fitzhardinge <[EMAIL PROTECTED]>
AuthorDate: Sat Jul 21 17:11:35 2007 +0200
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sat Jul 21 18:37:14 2007 -0700

    i386: fix iounmap's use of vm_struct's size field
    
    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 <[EMAIL PROTECTED]> for debugging the
    problem.
    
    [ Andi, it wasn't clear to me whether x86_64 needs the same fix. ]
    
    Signed-off-by: Jeremy Fitzhardinge <[EMAIL PROTECTED]>
    Cc: Dave Young <[EMAIL PROTECTED]>
    Cc: Chuck Ebbert <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 arch/i386/mm/ioremap.c  |    2 +-
 include/linux/vmalloc.h |    7 +++++++
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c
index fff08ae..0b27831 100644
--- a/arch/i386/mm/ioremap.c
+++ b/arch/i386/mm/ioremap.c
@@ -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();
        } 
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index c2b10ca..89338b4 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -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);
-
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