@@ -529,6 +529,8 @@ 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;
@@ -541,7 +543,7 @@ 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) {
This is a note to let you know that I have just added a patch titled s390/memory hotplug: prevent offline of active memory to the linux-3.5.y-queue branch of the 3.5.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-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 7adb147da53c4f2ff4a8915091d8c2d25fe1f4a4 Mon Sep 17 00:00:00 2001 From: Heiko Carstens <heiko.carstens@de.ibm.com> Date: Thu, 25 Apr 2013 10:03:15 +0200 Subject: [PATCH] s390/memory hotplug: prevent offline of active memory increments commit 94c163663fc1dcfc067a5fb3cc1446b9469975ce upstream. 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> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/s390/char/sclp_cmd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) -- 1.8.1.2