linux/drivers/base/memory.c
Michael Holzheu f5138e4221 kdump: add udev events for memory online/offline
Currently no udev events for memory hotplug "online" and "offline" are
generated:

  # udevadm monitor
  # echo offline > /sys/devices/system/memory/memory4/state
  ==> No event

When kdump is loaded, kexec detects the current memory configuration and
stores it in the pre-allocated ELF core header.  Therefore, for kdump it
is necessary to reload the kdump kernel with kexec when the memory
configuration changes (e.g.  for online/offline hotplug memory).

In order to do this automatically, udev rules should be used.  This kernel
patch adds udev events for "online" and "offline".  Together with this
kernel patch, the following udev rules for online/offline have to be added
to "/etc/udev/rules.d/98-kexec.rules":

  SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/etc/init.d/kdump restart"
  SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/etc/init.d/kdump restart"

[sfr@canb.auug.org.au: fixups for class to subsystem conversion]
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-12 20:13:11 -08:00

685 lines
16 KiB
C

/*
* Memory subsystem support
*
* Written by Matt Tolentino <matthew.e.tolentino@intel.com>
* Dave Hansen <haveblue@us.ibm.com>
*
* This file provides the necessary infrastructure to represent
* a SPARSEMEM-memory-model system's physical memory in /sysfs.
* All arch-independent code that assumes MEMORY_HOTPLUG requires
* SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/topology.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/memory.h>
#include <linux/kobject.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <asm/uaccess.h>
static DEFINE_MUTEX(mem_sysfs_mutex);
#define MEMORY_CLASS_NAME "memory"
static int sections_per_block;
static inline int base_memory_block_id(int section_nr)
{
return section_nr / sections_per_block;
}
static struct bus_type memory_subsys = {
.name = MEMORY_CLASS_NAME,
.dev_name = MEMORY_CLASS_NAME,
};
static BLOCKING_NOTIFIER_HEAD(memory_chain);
int register_memory_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&memory_chain, nb);
}
EXPORT_SYMBOL(register_memory_notifier);
void unregister_memory_notifier(struct notifier_block *nb)
{
blocking_notifier_chain_unregister(&memory_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_notifier);
static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
int register_memory_isolate_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_register(&memory_isolate_chain, nb);
}
EXPORT_SYMBOL(register_memory_isolate_notifier);
void unregister_memory_isolate_notifier(struct notifier_block *nb)
{
atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_isolate_notifier);
/*
* register_memory - Setup a sysfs device for a memory block
*/
static
int register_memory(struct memory_block *memory)
{
int error;
memory->dev.bus = &memory_subsys;
memory->dev.id = memory->start_section_nr / sections_per_block;
error = device_register(&memory->dev);
return error;
}
static void
unregister_memory(struct memory_block *memory)
{
BUG_ON(memory->dev.bus != &memory_subsys);
/* drop the ref. we got in remove_memory_block() */
kobject_put(&memory->dev.kobj);
device_unregister(&memory->dev);
}
unsigned long __weak memory_block_size_bytes(void)
{
return MIN_MEMORY_BLOCK_SIZE;
}
static unsigned long get_memory_block_size(void)
{
unsigned long block_sz;
block_sz = memory_block_size_bytes();
/* Validate blk_sz is a power of 2 and not less than section size */
if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
WARN_ON(1);
block_sz = MIN_MEMORY_BLOCK_SIZE;
}
return block_sz;
}
/*
* use this as the physical section index that this memsection
* uses.
*/
static ssize_t show_mem_start_phys_index(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem =
container_of(dev, struct memory_block, dev);
unsigned long phys_index;
phys_index = mem->start_section_nr / sections_per_block;
return sprintf(buf, "%08lx\n", phys_index);
}
static ssize_t show_mem_end_phys_index(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem =
container_of(dev, struct memory_block, dev);
unsigned long phys_index;
phys_index = mem->end_section_nr / sections_per_block;
return sprintf(buf, "%08lx\n", phys_index);
}
/*
* Show whether the section of memory is likely to be hot-removable
*/
static ssize_t show_mem_removable(struct device *dev,
struct device_attribute *attr, char *buf)
{
unsigned long i, pfn;
int ret = 1;
struct memory_block *mem =
container_of(dev, struct memory_block, dev);
for (i = 0; i < sections_per_block; i++) {
pfn = section_nr_to_pfn(mem->start_section_nr + i);
ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
}
return sprintf(buf, "%d\n", ret);
}
/*
* online, offline, going offline, etc.
*/
static ssize_t show_mem_state(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem =
container_of(dev, struct memory_block, dev);
ssize_t len = 0;
/*
* We can probably put these states in a nice little array
* so that they're not open-coded
*/
switch (mem->state) {
case MEM_ONLINE:
len = sprintf(buf, "online\n");
break;
case MEM_OFFLINE:
len = sprintf(buf, "offline\n");
break;
case MEM_GOING_OFFLINE:
len = sprintf(buf, "going-offline\n");
break;
default:
len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
mem->state);
WARN_ON(1);
break;
}
return len;
}
int memory_notify(unsigned long val, void *v)
{
return blocking_notifier_call_chain(&memory_chain, val, v);
}
int memory_isolate_notify(unsigned long val, void *v)
{
return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
}
/*
* The probe routines leave the pages reserved, just as the bootmem code does.
* Make sure they're still that way.
*/
static bool pages_correctly_reserved(unsigned long start_pfn,
unsigned long nr_pages)
{
int i, j;
struct page *page;
unsigned long pfn = start_pfn;
/*
* memmap between sections is not contiguous except with
* SPARSEMEM_VMEMMAP. We lookup the page once per section
* and assume memmap is contiguous within each section
*/
for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
if (WARN_ON_ONCE(!pfn_valid(pfn)))
return false;
page = pfn_to_page(pfn);
for (j = 0; j < PAGES_PER_SECTION; j++) {
if (PageReserved(page + j))
continue;
printk(KERN_WARNING "section number %ld page number %d "
"not reserved, was it already online?\n",
pfn_to_section_nr(pfn), j);
return false;
}
}
return true;
}
/*
* MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
* OK to have direct references to sparsemem variables in here.
*/
static int
memory_block_action(unsigned long phys_index, unsigned long action)
{
unsigned long start_pfn, start_paddr;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
struct page *first_page;
int ret;
first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
switch (action) {
case MEM_ONLINE:
start_pfn = page_to_pfn(first_page);
if (!pages_correctly_reserved(start_pfn, nr_pages))
return -EBUSY;
ret = online_pages(start_pfn, nr_pages);
break;
case MEM_OFFLINE:
start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
ret = remove_memory(start_paddr,
nr_pages << PAGE_SHIFT);
break;
default:
WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
"%ld\n", __func__, phys_index, action, action);
ret = -EINVAL;
}
return ret;
}
static int memory_block_change_state(struct memory_block *mem,
unsigned long to_state, unsigned long from_state_req)
{
int ret = 0;
mutex_lock(&mem->state_mutex);
if (mem->state != from_state_req) {
ret = -EINVAL;
goto out;
}
if (to_state == MEM_OFFLINE)
mem->state = MEM_GOING_OFFLINE;
ret = memory_block_action(mem->start_section_nr, to_state);
if (ret) {
mem->state = from_state_req;
goto out;
}
mem->state = to_state;
switch (mem->state) {
case MEM_OFFLINE:
kobject_uevent(&mem->dev.kobj, KOBJ_OFFLINE);
break;
case MEM_ONLINE:
kobject_uevent(&mem->dev.kobj, KOBJ_ONLINE);
break;
default:
break;
}
out:
mutex_unlock(&mem->state_mutex);
return ret;
}
static ssize_t
store_mem_state(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct memory_block *mem;
int ret = -EINVAL;
mem = container_of(dev, struct memory_block, dev);
if (!strncmp(buf, "online", min((int)count, 6)))
ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
else if(!strncmp(buf, "offline", min((int)count, 7)))
ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
if (ret)
return ret;
return count;
}
/*
* phys_device is a bad name for this. What I really want
* is a way to differentiate between memory ranges that
* are part of physical devices that constitute
* a complete removable unit or fru.
* i.e. do these ranges belong to the same physical device,
* s.t. if I offline all of these sections I can then
* remove the physical device?
*/
static ssize_t show_phys_device(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct memory_block *mem =
container_of(dev, struct memory_block, dev);
return sprintf(buf, "%d\n", mem->phys_device);
}
static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
static DEVICE_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
#define mem_create_simple_file(mem, attr_name) \
device_create_file(&mem->dev, &dev_attr_##attr_name)
#define mem_remove_simple_file(mem, attr_name) \
device_remove_file(&mem->dev, &dev_attr_##attr_name)
/*
* Block size attribute stuff
*/
static ssize_t
print_block_size(struct device *dev, struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%lx\n", get_memory_block_size());
}
static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
static int block_size_init(void)
{
return device_create_file(memory_subsys.dev_root,
&dev_attr_block_size_bytes);
}
/*
* Some architectures will have custom drivers to do this, and
* will not need to do it from userspace. The fake hot-add code
* as well as ppc64 will do all of their discovery in userspace
* and will require this interface.
*/
#ifdef CONFIG_ARCH_MEMORY_PROBE
static ssize_t
memory_probe_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
u64 phys_addr;
int nid;
int i, ret;
unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
phys_addr = simple_strtoull(buf, NULL, 0);
if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
return -EINVAL;
for (i = 0; i < sections_per_block; i++) {
nid = memory_add_physaddr_to_nid(phys_addr);
ret = add_memory(nid, phys_addr,
PAGES_PER_SECTION << PAGE_SHIFT);
if (ret)
goto out;
phys_addr += MIN_MEMORY_BLOCK_SIZE;
}
ret = count;
out:
return ret;
}
static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
static int memory_probe_init(void)
{
return device_create_file(memory_subsys.dev_root, &dev_attr_probe);
}
#else
static inline int memory_probe_init(void)
{
return 0;
}
#endif
#ifdef CONFIG_MEMORY_FAILURE
/*
* Support for offlining pages of memory
*/
/* Soft offline a page */
static ssize_t
store_soft_offline_page(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (strict_strtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
if (!pfn_valid(pfn))
return -ENXIO;
ret = soft_offline_page(pfn_to_page(pfn), 0);
return ret == 0 ? count : ret;
}
/* Forcibly offline a page, including killing processes. */
static ssize_t
store_hard_offline_page(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int ret;
u64 pfn;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (strict_strtoull(buf, 0, &pfn) < 0)
return -EINVAL;
pfn >>= PAGE_SHIFT;
ret = __memory_failure(pfn, 0, 0);
return ret ? ret : count;
}
static DEVICE_ATTR(soft_offline_page, 0644, NULL, store_soft_offline_page);
static DEVICE_ATTR(hard_offline_page, 0644, NULL, store_hard_offline_page);
static __init int memory_fail_init(void)
{
int err;
err = device_create_file(memory_subsys.dev_root,
&dev_attr_soft_offline_page);
if (!err)
err = device_create_file(memory_subsys.dev_root,
&dev_attr_hard_offline_page);
return err;
}
#else
static inline int memory_fail_init(void)
{
return 0;
}
#endif
/*
* Note that phys_device is optional. It is here to allow for
* differentiation between which *physical* devices each
* section belongs to...
*/
int __weak arch_get_memory_phys_device(unsigned long start_pfn)
{
return 0;
}
/*
* A reference for the returned object is held and the reference for the
* hinted object is released.
*/
struct memory_block *find_memory_block_hinted(struct mem_section *section,
struct memory_block *hint)
{
int block_id = base_memory_block_id(__section_nr(section));
struct device *hintdev = hint ? &hint->dev : NULL;
struct device *dev;
dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
if (hint)
put_device(&hint->dev);
if (!dev)
return NULL;
return container_of(dev, struct memory_block, dev);
}
/*
* For now, we have a linear search to go find the appropriate
* memory_block corresponding to a particular phys_index. If
* this gets to be a real problem, we can always use a radix
* tree or something here.
*
* This could be made generic for all device subsystems.
*/
struct memory_block *find_memory_block(struct mem_section *section)
{
return find_memory_block_hinted(section, NULL);
}
static int init_memory_block(struct memory_block **memory,
struct mem_section *section, unsigned long state)
{
struct memory_block *mem;
unsigned long start_pfn;
int scn_nr;
int ret = 0;
mem = kzalloc(sizeof(*mem), GFP_KERNEL);
if (!mem)
return -ENOMEM;
scn_nr = __section_nr(section);
mem->start_section_nr =
base_memory_block_id(scn_nr) * sections_per_block;
mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
mem->state = state;
mem->section_count++;
mutex_init(&mem->state_mutex);
start_pfn = section_nr_to_pfn(mem->start_section_nr);
mem->phys_device = arch_get_memory_phys_device(start_pfn);
ret = register_memory(mem);
if (!ret)
ret = mem_create_simple_file(mem, phys_index);
if (!ret)
ret = mem_create_simple_file(mem, end_phys_index);
if (!ret)
ret = mem_create_simple_file(mem, state);
if (!ret)
ret = mem_create_simple_file(mem, phys_device);
if (!ret)
ret = mem_create_simple_file(mem, removable);
*memory = mem;
return ret;
}
static int add_memory_section(int nid, struct mem_section *section,
unsigned long state, enum mem_add_context context)
{
struct memory_block *mem;
int ret = 0;
mutex_lock(&mem_sysfs_mutex);
mem = find_memory_block(section);
if (mem) {
mem->section_count++;
kobject_put(&mem->dev.kobj);
} else
ret = init_memory_block(&mem, section, state);
if (!ret) {
if (context == HOTPLUG &&
mem->section_count == sections_per_block)
ret = register_mem_sect_under_node(mem, nid);
}
mutex_unlock(&mem_sysfs_mutex);
return ret;
}
int remove_memory_block(unsigned long node_id, struct mem_section *section,
int phys_device)
{
struct memory_block *mem;
mutex_lock(&mem_sysfs_mutex);
mem = find_memory_block(section);
unregister_mem_sect_under_nodes(mem, __section_nr(section));
mem->section_count--;
if (mem->section_count == 0) {
mem_remove_simple_file(mem, phys_index);
mem_remove_simple_file(mem, end_phys_index);
mem_remove_simple_file(mem, state);
mem_remove_simple_file(mem, phys_device);
mem_remove_simple_file(mem, removable);
unregister_memory(mem);
kfree(mem);
} else
kobject_put(&mem->dev.kobj);
mutex_unlock(&mem_sysfs_mutex);
return 0;
}
/*
* need an interface for the VM to add new memory regions,
* but without onlining it.
*/
int register_new_memory(int nid, struct mem_section *section)
{
return add_memory_section(nid, section, MEM_OFFLINE, HOTPLUG);
}
int unregister_memory_section(struct mem_section *section)
{
if (!present_section(section))
return -EINVAL;
return remove_memory_block(0, section, 0);
}
/*
* Initialize the sysfs support for memory devices...
*/
int __init memory_dev_init(void)
{
unsigned int i;
int ret;
int err;
unsigned long block_sz;
ret = subsys_system_register(&memory_subsys, NULL);
if (ret)
goto out;
block_sz = get_memory_block_size();
sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
/*
* Create entries for memory sections that were found
* during boot and have been initialized
*/
for (i = 0; i < NR_MEM_SECTIONS; i++) {
if (!present_section_nr(i))
continue;
err = add_memory_section(0, __nr_to_section(i), MEM_ONLINE,
BOOT);
if (!ret)
ret = err;
}
err = memory_probe_init();
if (!ret)
ret = err;
err = memory_fail_init();
if (!ret)
ret = err;
err = block_size_init();
if (!ret)
ret = err;
out:
if (ret)
printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
return ret;
}