i386: fix iounmap's use of vm_struct's size field
authorJeremy Fitzhardinge <jeremy@goop.org>
Sat, 21 Jul 2007 15:11:35 +0000 (17:11 +0200)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Sun, 22 Jul 2007 01:37:14 +0000 (18:37 -0700)
commit9585116ba09f1d8c52d0a1346e20bb9d443e9c02
treec3380b477754d3d2d77fa8dbd08f0b0d08fdcadf
parenta2900975ef3f1df33c83e750cc1e490de3374ca8
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 <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>
arch/i386/mm/ioremap.c
include/linux/vmalloc.h