From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 1/4] hwpoison: prevent /dev/kmem from accessing hwpoison pages Date: Sat, 30 Jan 2010 17:25:10 +0800 Message-ID: <20100130093703.718660392@intel.com> References: <20100130092509.793222613@intel.com> Return-path: Received: from kanga.kvack.org ([205.233.56.17]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Ov8EF-0004CS-Ao for glkm-linux-mm-2@m.gmane.org; Mon, 13 Sep 2010 14:33:47 +0200 Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id E4FE75F0044 for ; Mon, 13 Sep 2010 08:32:08 -0400 (EDT) Content-Disposition: inline; filename=hwpoison-dev-kmem.patch Sender: owner-linux-mm@kvack.org To: Andrew Morton , Andi Kleen Cc: KAMEZAWA Hiroyuki , Greg KH , Benjamin Herrenschmidt , Christoph Lameter , Ingo Molnar , Tejun Heo , Nick Piggin , Wu Fengguang , LKML , Linux Memory Management List List-Id: linux-mm.kvack.org When /dev/kmem read()/write() encounters hwpoison page, stop it and return the amount of work done till now, or return -EIO if nothing have been copied. For simplicity, hwpoison pages accessed by vmalloc address are siliently skipped, instead of returning -EIO. CC: Greg KH CC: Andi Kleen CC: Benjamin Herrenschmidt CC: Christoph Lameter CC: Ingo Molnar CC: Tejun Heo CC: Nick Piggin CC: KAMEZAWA Hiroyuki Signed-off-by: Wu Fengguang --- drivers/char/mem.c | 18 ++++++++++++++---- mm/vmalloc.c | 4 ++-- 2 files changed, 16 insertions(+), 6 deletions(-) --- linux-mm.orig/drivers/char/mem.c 2010-01-30 17:14:12.000000000 +0800 +++ linux-mm/drivers/char/mem.c 2010-01-30 17:20:18.000000000 +0800 @@ -426,6 +426,9 @@ static ssize_t read_kmem(struct file *fi */ kbuf = xlate_dev_kmem_ptr((char *)p); + if (unlikely(virt_addr_valid(kbuf) && + PageHWPoison(virt_to_page(kbuf)))) + return -EIO; if (copy_to_user(buf, kbuf, sz)) return -EFAULT; buf += sz; @@ -471,6 +474,7 @@ do_write_kmem(unsigned long p, const cha { ssize_t written, sz; unsigned long copied; + int err = 0; written = 0; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED @@ -497,13 +501,19 @@ do_write_kmem(unsigned long p, const cha */ ptr = xlate_dev_kmem_ptr((char *)p); + if (unlikely(virt_addr_valid(ptr) && + PageHWPoison(virt_to_page(ptr)))) { + err = -EIO; + break; + } + copied = copy_from_user(ptr, buf, sz); if (copied) { written += sz - copied; - if (written) - break; - return -EFAULT; + err = -EFAULT; + break; } + buf += sz; p += sz; count -= sz; @@ -511,7 +521,7 @@ do_write_kmem(unsigned long p, const cha } *ppos += written; - return written; + return written ? written : err; } --- linux-mm.orig/mm/vmalloc.c 2010-01-30 17:14:15.000000000 +0800 +++ linux-mm/mm/vmalloc.c 2010-01-30 17:20:18.000000000 +0800 @@ -1669,7 +1669,7 @@ static int aligned_vread(char *buf, char * interface, rarely used. Instead of that, we'll use * kmap() and get small overhead in this access function. */ - if (p) { + if (p && !PageHWPoison(p)) { /* * we can expect USER0 is not used (see vread/vwrite's * function description) @@ -1708,7 +1708,7 @@ static int aligned_vwrite(char *buf, cha * interface, rarely used. Instead of that, we'll use * kmap() and get small overhead in this access function. */ - if (p) { + if (p && !PageHWPoison(p)) { /* * we can expect USER0 is not used (see vread/vwrite's * function description) -- 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/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org