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SubjectRe: [PATCH 1/5] v2 Split the memory_block structure
On Thu, 15 Jul 2010 13:37:51 -0500
Nathan Fontenot <nfont@austin.ibm.com> wrote:

> Split the memory_block struct into a memory_block
> struct to cover each sysfs directory and a new memory_block_section
> struct for each memory section covered by the sysfs directory.
> This change allows for creation of memory sysfs directories that
> can span multiple memory sections.
>
> This can be beneficial in that it can reduce the number of memory
> sysfs directories created at boot. This also allows different
> architectures to define how many memory sections are covered by
> a sysfs directory.
>
> Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
> ---
> drivers/base/memory.c | 222 ++++++++++++++++++++++++++++++++++---------------
> include/linux/memory.h | 11 +-
> 2 files changed, 167 insertions(+), 66 deletions(-)
>
> Index: linux-2.6/drivers/base/memory.c
> ===================================================================
> --- linux-2.6.orig/drivers/base/memory.c 2010-07-15 08:48:41.000000000 -0500
> +++ linux-2.6/drivers/base/memory.c 2010-07-15 09:55:54.000000000 -0500
> @@ -28,6 +28,14 @@
> #include <asm/uaccess.h>
>
> #define MEMORY_CLASS_NAME "memory"
> +#define MIN_MEMORY_BLOCK_SIZE (1 << SECTION_SIZE_BITS)
> +
> +static int sections_per_block;
> +
> +static inline int base_memory_block_id(int section_nr)
> +{
> + return (section_nr / sections_per_block) * sections_per_block;
> +}
>
> static struct sysdev_class memory_sysdev_class = {
> .name = MEMORY_CLASS_NAME,
> @@ -94,10 +102,9 @@
> }
>
> static void
> -unregister_memory(struct memory_block *memory, struct mem_section *section)
> +unregister_memory(struct memory_block *memory)
> {
> BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
> - BUG_ON(memory->sysdev.id != __section_nr(section));
>
> /* drop the ref. we got in remove_memory_block() */
> kobject_put(&memory->sysdev.kobj);
> @@ -123,13 +130,20 @@
> static ssize_t show_mem_removable(struct sys_device *dev,
> struct sysdev_attribute *attr, char *buf)
> {
> + struct memory_block *mem;
> + struct memory_block_section *mbs;
> unsigned long start_pfn;
> - int ret;
> - struct memory_block *mem =
> - container_of(dev, struct memory_block, sysdev);
> + int ret = 1;
> +
> + mem = container_of(dev, struct memory_block, sysdev);
> + mutex_lock(&mem->state_mutex);
>
> - start_pfn = section_nr_to_pfn(mem->phys_index);
> - ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
> + list_for_each_entry(mbs, &mem->sections, next) {
> + start_pfn = section_nr_to_pfn(mbs->phys_index);
> + ret &= is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
> + }
> +
> + mutex_unlock(&mem->state_mutex);

Hmm, this means memory cab be offlined the while memory block section. Right ?
Please write this fact in patch description...
And Documentaion/memory_hotplug.txt as "From user's perspective, memory section
is not a unit of memory hotplug anymore".
And descirbe about a new rule.


> return sprintf(buf, "%d\n", ret);
> }
>
> @@ -182,16 +196,16 @@
> * OK to have direct references to sparsemem variables in here.
> */
> static int
> -memory_block_action(struct memory_block *mem, unsigned long action)
> +memory_block_action(struct memory_block_section *mbs, unsigned long action)
> {
> int i;
> unsigned long psection;
> unsigned long start_pfn, start_paddr;
> struct page *first_page;
> int ret;
> - int old_state = mem->state;
> + int old_state = mbs->state;
>
> - psection = mem->phys_index;
> + psection = mbs->phys_index;
> first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
>
> /*
> @@ -217,18 +231,18 @@
> ret = online_pages(start_pfn, PAGES_PER_SECTION);
> break;
> case MEM_OFFLINE:
> - mem->state = MEM_GOING_OFFLINE;
> + mbs->state = MEM_GOING_OFFLINE;
> start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
> ret = remove_memory(start_paddr,
> PAGES_PER_SECTION << PAGE_SHIFT);
> if (ret) {
> - mem->state = old_state;
> + mbs->state = old_state;
> break;
> }
> break;
> default:
> WARN(1, KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
> - __func__, mem, action, action);
> + __func__, mbs, action, action);
> ret = -EINVAL;
> }
>
> @@ -238,19 +252,34 @@

And please check quilt's diff option.
Usual patche in ML shows a function name in any changes, as
@@ -241,6 +293,8 @@ static int memory_block_change_state(str

Maybe "-p" option is lacked..


> static int memory_block_change_state(struct memory_block *mem,
> unsigned long to_state, unsigned long from_state_req)
> {
> + struct memory_block_section *mbs;
> int ret = 0;
> +
> mutex_lock(&mem->state_mutex);
>
> - if (mem->state != from_state_req) {
> - ret = -EINVAL;
> - goto out;
> + list_for_each_entry(mbs, &mem->sections, next) {
> + if (mbs->state != from_state_req)
> + continue;
> +
> + ret = memory_block_action(mbs, to_state);
> + if (ret)
> + break;
> + }
> +
> + if (ret) {
> + list_for_each_entry(mbs, &mem->sections, next) {
> + if (mbs->state == from_state_req)
> + continue;
> +
> + if (memory_block_action(mbs, to_state))
> + printk(KERN_ERR "Could not re-enable memory "
> + "section %lx\n", mbs->phys_index);

Why re-enable only ? online->fail->offline never happens ?
If so, please add comment at least.
BTW, is it guaranteed that all sections under a block has same state after
boot ?

> + }
> }
>
> - ret = memory_block_action(mem, to_state);
> if (!ret)
> mem->state = to_state;
>
> -out:
> mutex_unlock(&mem->state_mutex);
> return ret;
> }
> @@ -260,20 +289,15 @@
> struct sysdev_attribute *attr, const char *buf, size_t count)
> {
> struct memory_block *mem;
> - unsigned int phys_section_nr;
> int ret = -EINVAL;
>
> mem = container_of(dev, struct memory_block, sysdev);
> - phys_section_nr = mem->phys_index;
> -
> - if (!present_section_nr(phys_section_nr))
> - goto out;
>
I'm sorry but I couldn't remember why this check was necessary...



> 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);
> -out:
> +
> if (ret)
> return ret;
> return count;
> @@ -435,39 +459,6 @@
> return 0;
> }
>
> -static int add_memory_block(int nid, struct mem_section *section,
> - unsigned long state, enum mem_add_context context)
> -{
> - struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> - unsigned long start_pfn;
> - int ret = 0;
> -
> - if (!mem)
> - return -ENOMEM;
> -
> - mem->phys_index = __section_nr(section);
> - mem->state = state;
> - mutex_init(&mem->state_mutex);
> - start_pfn = section_nr_to_pfn(mem->phys_index);
> - mem->phys_device = arch_get_memory_phys_device(start_pfn);
> -
> - ret = register_memory(mem, section);
> - if (!ret)
> - ret = mem_create_simple_file(mem, 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);
> - if (!ret) {
> - if (context == HOTPLUG)
> - ret = register_mem_sect_under_node(mem, nid);
> - }
> -
> - return ret;
> -}
> -

I don't say strongly but this kind of move-code should be done in another patch.


> /*
> * For now, we have a linear search to go find the appropriate
> * memory_block corresponding to a particular phys_index. If
> @@ -482,12 +473,13 @@
> struct sys_device *sysdev;
> struct memory_block *mem;
> char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
> + int block_id = base_memory_block_id(__section_nr(section));
>
> /*
> * This only works because we know that section == sysdev->id
> * slightly redundant with sysdev_register()
> */
> - sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
> + sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, block_id);
>
> kobj = kset_find_obj(&memory_sysdev_class.kset, name);
> if (!kobj)
> @@ -499,18 +491,98 @@
> return mem;
> }
>
> +static int add_mem_block_section(struct memory_block *mem,
> + int section_nr, unsigned long state)
> +{
> + struct memory_block_section *mbs;
> +
> + mbs = kzalloc(sizeof(*mbs), GFP_KERNEL);
> + if (!mbs)
> + return -ENOMEM;
> +
> + mbs->phys_index = section_nr;
> + mbs->state = state;
> +
> + list_add(&mbs->next, &mem->sections);
> + return 0;
> +}

Doesn't this "sections" need to be sorted ? Hmm.


> +
> +static int add_memory_block(int nid, struct mem_section *section,
> + unsigned long state, enum mem_add_context context)
> +{
> + struct memory_block *mem;
> + int ret = 0;
> +
> + mem = find_memory_block(section);
> + if (!mem) {
> + unsigned long start_pfn;
> +
> + mem = kzalloc(sizeof(*mem), GFP_KERNEL);
> + if (!mem)
> + return -ENOMEM;
> +
> + mem->state = state;
> + mutex_init(&mem->state_mutex);
> + start_pfn = section_nr_to_pfn(__section_nr(section));
> + mem->phys_device = arch_get_memory_phys_device(start_pfn);
> + INIT_LIST_HEAD(&mem->sections);
> +
> + mutex_lock(&mem->state_mutex);
> +
> + ret = register_memory(mem, section);
> + if (!ret)
> + ret = mem_create_simple_file(mem, 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);
> + if (!ret) {
> + if (context == HOTPLUG)
> + ret = register_mem_sect_under_node(mem, nid);
> + }
> + } else {
> + kobject_put(&mem->sysdev.kobj);
> + mutex_lock(&mem->state_mutex);
> + }
> +
> + if (!ret)
> + ret = add_mem_block_section(mem, __section_nr(section), state);
> +
> + mutex_unlock(&mem->state_mutex);
> + return ret;
> +}
> +
> int remove_memory_block(unsigned long node_id, struct mem_section *section,
> int phys_device)
> {
> struct memory_block *mem;
> + struct memory_block_section *mbs, *tmp;
> + int section_nr = __section_nr(section);
>
> mem = find_memory_block(section);
> - unregister_mem_sect_under_nodes(mem);
> - mem_remove_simple_file(mem, phys_index);
> - mem_remove_simple_file(mem, state);
> - mem_remove_simple_file(mem, phys_device);
> - mem_remove_simple_file(mem, removable);
> - unregister_memory(mem, section);
> + mutex_lock(&mem->state_mutex);
> +
> + /* remove the specified section */
> + list_for_each_entry_safe(mbs, tmp, &mem->sections, next) {
> + if (mbs->phys_index == section_nr) {
> + list_del(&mbs->next);
> + kfree(mbs);
> + }
> + }
> +
> + mutex_unlock(&mem->state_mutex);
> +
> + if (list_empty(&mem->sections)) {
> + unregister_mem_sect_under_nodes(mem);
> + mem_remove_simple_file(mem, 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);
> + }
>
> return 0;
> }
> @@ -532,6 +604,24 @@
> return remove_memory_block(0, section, 0);
> }
>
> +u32 __weak memory_block_size(void)
> +{
> + return MIN_MEMORY_BLOCK_SIZE;
> +}
> +
> +static u32 get_memory_block_size(void)
> +{
> + u32 blk_sz;
> +
> + blk_sz = memory_block_size();
> +
> + /* Validate blk_sz is a power of 2 and not less than section size */
> + if ((blk_sz & (blk_sz - 1)) || (blk_sz < MIN_MEMORY_BLOCK_SIZE))
> + blk_sz = MIN_MEMORY_BLOCK_SIZE;
> +
> + return blk_sz;
> +}
> +
> /*
> * Initialize the sysfs support for memory devices...
> */
> @@ -540,12 +630,16 @@
> unsigned int i;
> int ret;
> int err;
> + int block_sz;
>
> memory_sysdev_class.kset.uevent_ops = &memory_uevent_ops;
> ret = sysdev_class_register(&memory_sysdev_class);
> 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
> Index: linux-2.6/include/linux/memory.h
> ===================================================================
> --- linux-2.6.orig/include/linux/memory.h 2010-07-15 08:48:41.000000000 -0500
> +++ linux-2.6/include/linux/memory.h 2010-07-15 09:54:06.000000000 -0500
> @@ -19,9 +19,15 @@
> #include <linux/node.h>
> #include <linux/compiler.h>
> #include <linux/mutex.h>
> +#include <linux/list.h>
>
> -struct memory_block {
> +struct memory_block_section {
> + unsigned long state;
> unsigned long phys_index;
> + struct list_head next;
> +};
> +
> +struct memory_block {
> unsigned long state;
> /*
> * This serializes all state change requests. It isn't
> @@ -34,6 +40,7 @@
> void *hw; /* optional pointer to fw/hw data */
> int (*phys_callback)(struct memory_block *);
> struct sys_device sysdev;
> + struct list_head sections;
> };
>
> int arch_get_memory_phys_device(unsigned long start_pfn);
> @@ -113,7 +120,7 @@
> extern int remove_memory_block(unsigned long, struct mem_section *, int);
> extern int memory_notify(unsigned long val, void *v);
> extern int memory_isolate_notify(unsigned long val, void *v);
> -extern struct memory_block *find_memory_block(unsigned long);
> +extern struct memory_block *find_memory_block(struct mem_section *);
> extern int memory_is_hidden(struct mem_section *);
> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
> enum mem_add_context { BOOT, HOTPLUG };
>

Okay, please go ahead. But my 1st impression is that IBM should increase ppc's
SECTION_SIZE ;)

Thanks,
-Kame






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