From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Date: Thu, 30 Jan 2014 15:14:02 +0000 (+0100)
Subject: s390/dump: Fix dump memory detection
X-Git-Tag: v3.2.56~126
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=41d1e615ecd7ef201ad332bba6fc6609f1bcb063;p=pandora-kernel.git

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@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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