Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH for review] [28/48] i386: fix iounmap's use of vm_struct's size field | Date | Thu, 19 Jul 2007 15:48:58 +0200 (CEST) |
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From: Jeremy Fitzhardinge <jeremy@goop.org>
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> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Dave Young <hidave.darkstar@gmail.com> Cc: Chuck Ebbert <cebbert@redhat.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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