From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Tue, 22 Sep 2009 00:02:34 +0000 (-0700)
Subject: kcore: fix vread/vwrite to be aware of holes
X-Git-Tag: v2.6.32-rc1~532
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d0107eb07320b5d37c0f8a9f015534caebb28a48;p=pandora-kernel.git

kcore: fix vread/vwrite to be aware of holes

vread/vwrite access vmalloc area without checking there is a page or not.
In most case, this works well.

In old ages, the caller of get_vm_ara() is only IOREMAP and there is no
memory hole within vm_struct's [addr...addr + size - PAGE_SIZE] (
-PAGE_SIZE is for a guard page.)

After per-cpu-alloc patch, it uses get_vm_area() for reserve continuous
virtual address but remap _later_.  There tend to be a hole in valid
vmalloc area in vm_struct lists.  Then, skip the hole (not mapped page) is
necessary.  This patch updates vread/vwrite() for avoiding memory hole.

Routines which access vmalloc area without knowing for which addr is used
are
  - /proc/kcore
  - /dev/kmem

kcore checks IOREMAP, /dev/kmem doesn't.  After this patch, IOREMAP is
checked and /dev/kmem will avoid to read/write it.  Fixes to /proc/kcore
will be in the next patch in series.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Mike Smith <scgtrp@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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