[3.8.y.z extended stable] Patch "s390/dump: Fix dump memory detection" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    s390/dump: Fix dump memory detection

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 1ada9e1fdd28986a0ed4cd183ee3672cbd0d8f99 Mon Sep 17 00:00:00 2001
From: Michael Holzheu <holzheu at linux.vnet.ibm.com>
Date: Thu, 30 Jan 2014 16:14:02 +0100
Subject: s390/dump: Fix dump memory detection

commit d7736ff5be31edaa4fe5ab62810c64529a24b149 upstream.

Dumps created by kdump or zfcpdump can contain invalid memory holes when
dumping z/VM systems that have memory pressure.

For example:

   # zgetdump -i /proc/vmcore.
   Memory map:
   0000000000000000 - 0000000000bfffff (12 MB)
   0000000000e00000 - 00000000014fffff (7 MB)
   000000000bd00000 - 00000000f3bfffff (3711 MB)

The memory detection function find_memory_chunks() issues tprot to
find valid memory chunks. In case of CMM it can happen that pages are
marked as unstable via set_page_unstable() in arch_free_page().
If z/VM has released that pages, tprot returns -EFAULT and indicates
a memory hole.

So fix this and switch off CMM in case of kdump or zfcpdump.

Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/s390/mm/page-states.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/s390/mm/page-states.c b/arch/s390/mm/page-states.c
index a90d45e..27c50f4 100644
--- a/arch/s390/mm/page-states.c
+++ b/arch/s390/mm/page-states.c
@@ -12,6 +12,8 @@
 #include <linux/mm.h>
 #include <linux/gfp.h>
 #include <linux/init.h>
+#include <asm/setup.h>
+#include <asm/ipl.h>

 #define ESSA_SET_STABLE		1
 #define ESSA_SET_UNUSED		2
@@ -41,6 +43,14 @@ void __init cmma_init(void)

 	if (!cmma_flag)
 		return;
+	/*
+	 * Disable CMM for dump, otherwise  the tprot based memory
+	 * detection can fail because of unstable pages.
+	 */
+	if (OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP) {
+		cmma_flag = 0;
+		return;
+	}
 	asm volatile(
 		"       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
 		"0:     la      %0,0\n"
--
1.8.3.2