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SubjectRe: [PATCH 1/7] Split the memory_block structure
Thanks for the review, answers below...

-Nathan

On 07/13/2010 01:18 AM, KAMEZAWA Hiroyuki wrote:
>
> plz cc linux-mm in the next time...
> And please incudes updates for Documentation/memory-hotplug.txt.
>

will do.
>
> On Mon, 12 Jul 2010 10:42:06 -0500
> Nathan Fontenot <nfont@austin.ibm.com> wrote:
>
>> This patch splits 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 also updates the routine handling memory_block creation
>> and manipulation to use these updated structures.
>>
>
> Could you clarify the number of memory_block_section per memory_block ?

The default number of memory_block_sections per memory block is 1. The
memory_block_size() routine (defined as __weak) sets the size of the
memory block, and thus the number of memory_block_sections.

The current view of memory in sysfs where each directory covers a single
memory section should still hold for everyone, unless a arch defines
their own memory_section_size routine to alter the behavior.

>
>
>> Signed -off-by: Nathan Fontenot <nfont@austin.ibm.com>
>> ---
>> drivers/base/memory.c | 228 +++++++++++++++++++++++++++++++++++--------------
>> include/linux/memory.h | 11 +-
>> 2 files changed, 172 insertions(+), 67 deletions(-)
>>
>> Index: linux-2.6/drivers/base/memory.c
>> ===================================================================
>> --- linux-2.6.orig/drivers/base/memory.c 2010-07-08 11:27:21.000000000 -0500
>> +++ linux-2.6/drivers/base/memory.c 2010-07-09 14:23:09.000000000 -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;
>> +
> some default value, plz. Does this can be determined only by .config ?

The default is 1. This is determined in the get_memory_block_size() which
is called from the memory sysfs init routine.

>
>
>> +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)
>> {
>> - unsigned long start_pfn;
>> - int ret;
>> - struct memory_block *mem =
>> - container_of(dev, struct memory_block, sysdev);
>> + struct list_head *pos, *tmp;
>> + struct memory_block *mem;
>> + int ret = 1;
>> +
>> + mem = container_of(dev, struct memory_block, sysdev);
>> + list_for_each_safe(pos, tmp, &mem->sections) {
>> + struct memory_block_section *mbs;
>> + unsigned long start_pfn;
>> +
>> + mbs = list_entry(pos, struct memory_block_section, next);
>
> list_for_each_entry ?

I went with list_for_each_safe() here since I am not holding the mutex
while walking the list. Perhaps this should be changed to take the
mutex and use list_for_each_entry().

>
>
>
>> + start_pfn = section_nr_to_pfn(mbs->phys_index);
>> + ret &= is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
>> + }
>
> Hmm, them, only when the whole memory block is removable, it's shown as
> removable. Right ?
> Does it meets ppc guy's requirements ?

Yes, and yes.

>
>>
>> - start_pfn = section_nr_to_pfn(mem->phys_index);
>> - ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
>> return sprintf(buf, "%d\n", ret);
>> }
>
> Hmm...can't you print removable information as bitmap, here ?
> overkill ?

We could print it as a bitmap, but I think it would be overkill. The
memory add/remove routines work on a memory_block such that all
memory_block_sections in the memory_block are added/removed as a whole.
Given this, I figured we only needed to know if the entire memory_block
is removable.

>
>
>>
>> @@ -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;
>> ot-option-to-disable-memory-hotplug.patch
>> + int old_state = mbs->state;
>
> Where is this noise from ?

Yuck! I'll take a look. That shouldn't be there obviously.

>
>>
>> - 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 +252,40 @@
>> static int memory_block_change_state(struct memory_block *mem,
>> unsigned long to_state, unsigned long from_state_req)
>> {
>> + struct memory_block_section *mbs;
>> + struct list_head *pos;
>> int ret = 0;
>> +
>> mutex_lock(&mem->state_mutex);
>>
>> - if (mem->state != from_state_req) {
>> - ret = -EINVAL;
>> - goto out;
>> + list_for_each(pos, &mem->sections) {
>> + mbs = list_entry(pos, struct memory_block_section, next);
>> +
>
> list_for_each_entry() ?

That could be done here.

>
>> + if (mbs->state != from_state_req)
>> + continue;
>> +
>> + ret = memory_block_action(mbs, to_state);
>> + if (ret)
>> + break;
>> + }
>
> Then, all actions will be affect all memory sections under memory block ?
> (Hmm..maybe have to see following patches ?)

Correct. Add/remove actions will work on a memory_block as a whole.

>
>
>> +
>> + if (ret) {
>> + list_for_each(pos, &mem->sections) {
>> + mbs = list_entry(pos, struct memory_block_section,
>> + next);
>> +
> list_for_each_entry() ?

got it. :)

>
>> + 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);
>> + }
>> }
>>
>> - ret = memory_block_action(mem, to_state);
>> if (!ret)
>> mem->state = to_state;
>>
>> -out:
>> mutex_unlock(&mem->state_mutex);
>> return ret;
>> }
>> @@ -260,20 +295,15 @@
>> struct sysdev_attribute *attr, const char *buf, size_t count)
>> {
>
> Hmm, store_mem_state() ? What diff option are you using ?

Yes, this is store_mem_state.

Patches were generated with quilt.

>
>
>> 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;
>>
>> 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 +465,6 @@
>> 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;
>> -}
>> -
>
>
> please divide clean-up and logic-change patches into their own..

ok.
>
>
>> /*
>> * For now, we have a linear search to go find the appropriate
>> * memory_block corresponding to a particular phys_index. If
>> @@ -482,12 +479,13 @@
>> 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);
>
> Hmm. Then, the user has to calculate block-id in addtion to section-id.
> Can't we use memory block name as memory%d-%d(start-end) ?

I am not attached to a particular name for the directories. I think
keeping the memory%d, where %d is the starting id makes the code that splits
the directory cleaner.

In a later patch I add a new file for each directory that has the ending
id in it so users can easily determine the start and end id's of the
memory block.

>
>
>
>>
>> kobj = kset_find_obj(&memory_sysdev_class.kset, name);
>> if (!kobj)
>> @@ -498,19 +496,97 @@
>>
>> 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;
>> +}
>> +
>> +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);
>
> I guess you need to add changes to find_memory_block. section-ID != block-ID.

That is above, see the line

>> + int block_id = base_memory_block_id(__section_nr(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);
>
> I'm not sure this phys_device is properly set in any arch...but this changes in
> granule will not affect ?

I don't think so, hopefully someone will speak up if this causes an issue.

>
>> +
>> + 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);
>> + }
>> +
>> + if (!ret)
>> + ret = add_mem_block_section(mem, __section_nr(section), state);
>> +
>> + 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;
>> + struct list_head *pos, *tmp;
>> + int section_nr = __section_nr(section);
>>
>> mem = find_memory_block(section);
>
> ditto.
>
>> - 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_safe(pos, tmp, &mem->sections) {
>> + mbs = list_entry(pos, struct memory_block_section, next);
>> +
> list_for_each_entry_safe ?

yep. :)

>
>> + 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 +608,24 @@
>> 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 +634,16 @@
>> 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 2010-07-08 11:27:21.000000000 -0500
>> +++ linux-2.6/include/linux/memory.h 2010-07-09 14:22:44.000000000 -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 };
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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>>
>



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