From 9585116ba09f1d8c52d0a1346e20bb9d443e9c02 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Sat, 21 Jul 2007 17:11:35 +0200 Subject: [PATCH] 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 for debugging the problem. [ Andi, it wasn't clear to me whether x86_64 needs the same fix. ] Signed-off-by: Jeremy Fitzhardinge Cc: Dave Young Cc: Chuck Ebbert Signed-off-by: Andrew Morton Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/i386/mm/ioremap.c | 2 +- include/linux/vmalloc.h | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c index fff08ae7b5ed..0b278315d737 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 c2b10cae5da5..89338b468d0d 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); -- 2.20.1