From: Jeremy Fitzhardinge <[EMAIL PROTECTED]> 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]> Signed-off-by: Andi Kleen <[EMAIL PROTECTED]> Cc: Dave Young <[EMAIL PROTECTED]> Cc: Chuck Ebbert <[EMAIL PROTECTED]> Cc: Andi Kleen <[EMAIL PROTECTED]> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> --- arch/i386/mm/ioremap.c | 2 +- include/linux/vmalloc.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) Index: linux/arch/i386/mm/ioremap.c =================================================================== --- linux.orig/arch/i386/mm/ioremap.c +++ linux/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(); } Index: linux/include/linux/vmalloc.h =================================================================== --- linux.orig/include/linux/vmalloc.h +++ linux/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); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/