Commit d7736ff5 authored Jan 30, 2014 by Michael Holzheu Committed by Martin Schwidefsky Feb 04, 2014

s390/dump: Fix dump memory detection



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.

Cc: <stable@vger.kernel.org>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent b7c5b1aa

arch/s390/mm/page-states.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -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"