linux/arch/s390/mm/page-states.c
Michael Holzheu d7736ff5be 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>
2014-02-04 15:39:51 +01:00

125 lines
2.5 KiB
C

/*
* Copyright IBM Corp. 2008
*
* Guest page hinting for unused pages.
*
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#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
static int cmma_flag = 1;
static int __init cmma(char *str)
{
char *parm;
parm = strstrip(str);
if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
cmma_flag = 1;
return 1;
}
cmma_flag = 0;
if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
return 1;
return 0;
}
__setup("cmma=", cmma);
void __init cmma_init(void)
{
register unsigned long tmp asm("0") = 0;
register int rc asm("1") = -EOPNOTSUPP;
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:\n"
EX_TABLE(0b,1b)
: "+&d" (rc), "+&d" (tmp));
if (rc)
cmma_flag = 0;
}
static inline void set_page_unstable(struct page *page, int order)
{
int i, rc;
for (i = 0; i < (1 << order); i++)
asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
: "=&d" (rc)
: "a" (page_to_phys(page + i)),
"i" (ESSA_SET_UNUSED));
}
void arch_free_page(struct page *page, int order)
{
if (!cmma_flag)
return;
set_page_unstable(page, order);
}
static inline void set_page_stable(struct page *page, int order)
{
int i, rc;
for (i = 0; i < (1 << order); i++)
asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
: "=&d" (rc)
: "a" (page_to_phys(page + i)),
"i" (ESSA_SET_STABLE));
}
void arch_alloc_page(struct page *page, int order)
{
if (!cmma_flag)
return;
set_page_stable(page, order);
}
void arch_set_page_states(int make_stable)
{
unsigned long flags, order, t;
struct list_head *l;
struct page *page;
struct zone *zone;
if (!cmma_flag)
return;
if (make_stable)
drain_local_pages(NULL);
for_each_populated_zone(zone) {
spin_lock_irqsave(&zone->lock, flags);
for_each_migratetype_order(order, t) {
list_for_each(l, &zone->free_area[order].free_list[t]) {
page = list_entry(l, struct page, lru);
if (make_stable)
set_page_stable(page, order);
else
set_page_unstable(page, order);
}
}
spin_unlock_irqrestore(&zone->lock, flags);
}
}