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authorHeiko Carstens <heiko.carstens@de.ibm.com>2013-04-25 12:03:15 +0400
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-04-26 11:07:10 +0400
commit94c163663fc1dcfc067a5fb3cc1446b9469975ce (patch)
tree438604c3bc95a1ed22ea4f9e17f2014de800f75e /drivers/s390
parent581618f226e83eb0fbe81ba2a623c6a55cbb7487 (diff)
downloadlinux-94c163663fc1dcfc067a5fb3cc1446b9469975ce.tar.xz
s390/memory hotplug: prevent offline of active memory increments
In case a machine supports memory hotplug all active memory increments present at IPL time have been initialized with a "usecount" of 1. This is wrong if the memory increment size is larger than the memory section size of the memory hotplug code. If that is the case the usecount must be initialized with the number of memory sections that fit into one memory increment. Otherwise it is possible to put a memory increment into standby state even if there are still active sections. Afterwards addressing exceptions might happen which cause the kernel to panic. However even worse, if a memory increment was put into standby state and afterwards into active state again, it's contents would have been zeroed, leading to memory corruption. This was only an issue for machines that support standby memory and have at least 256GB memory. This is broken since commit fdb1bb15 "[S390] sclp/memory hotplug: fix initial usecount of increments". Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: stable@vger.kernel.org # 2.6.39+ Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/char/sclp_cmd.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index cd798386b622..178836ec252b 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -561,6 +561,8 @@ static void __init sclp_add_standby_memory(void)
add_memory_merged(0);
}
+#define MEM_SCT_SIZE (1UL << SECTION_SIZE_BITS)
+
static void __init insert_increment(u16 rn, int standby, int assigned)
{
struct memory_increment *incr, *new_incr;
@@ -573,7 +575,7 @@ static void __init insert_increment(u16 rn, int standby, int assigned)
new_incr->rn = rn;
new_incr->standby = standby;
if (!standby)
- new_incr->usecount = 1;
+ new_incr->usecount = rzm > MEM_SCT_SIZE ? rzm/MEM_SCT_SIZE : 1;
last_rn = 0;
prev = &sclp_mem_list;
list_for_each_entry(incr, &sclp_mem_list, list) {