Hello.
This patch set is to rearrange event notifier for memory hotplug,
because the old notifier has some defects. For example, there is no
information like new memory's pfn and # of pages for callback functions.
Fortunately, nothing uses this notifier so far, there is no impact by
this change. (SLUB will use this after this patch set to make
kmem_cache_node structure).
In addition, descriptions of notifer is added to memory hotplug
document.
This patch was a part of patch set to make kmem_cache_node of SLUB
to avoid panic of memory online. But, I think this change becomes
not only for SLUB but also for others. So, I extracted this from it.
This patch set is for 2.6.23-mm1.
I tested this patch on my ia64 box.
Please apply.
Bye.
--
Yasunori Goto
Add description about event notification callback routine to the document.
Signed-off-by: Yasunori Goto <[email protected]>
---
Documentation/memory-hotplug.txt | 58 ++++++++++++++++++++++++++++++++++++---
1 file changed, 55 insertions(+), 3 deletions(-)
Index: current/Documentation/memory-hotplug.txt
===================================================================
--- current.orig/Documentation/memory-hotplug.txt 2007-10-17 15:57:50.000000000 +0900
+++ current/Documentation/memory-hotplug.txt 2007-10-17 21:26:30.000000000 +0900
@@ -2,7 +2,8 @@
Memory Hotplug
==============
-Last Updated: Jul 28 2007
+Created: Jul 28 2007
+Add description of notifier of memory hotplug Oct 11 2007
This document is about memory hotplug including how-to-use and current status.
Because Memory Hotplug is still under development, contents of this text will
@@ -24,7 +25,8 @@ be changed often.
6.1 Memory offline and ZONE_MOVABLE
6.2. How to offline memory
7. Physical memory remove
-8. Future Work List
+8. Memory hotplug event notifier
+9. Future Work List
Note(1): x86_64's has special implementation for memory hotplug.
This text does not describe it.
@@ -307,8 +309,58 @@ Need more implementation yet....
- Notification completion of remove works by OS to firmware.
- Guard from remove if not yet.
+--------------------------------
+8. Memory hotplug event notifier
+--------------------------------
+Memory hotplug has event notifer. There are 6 types of notification.
+
+MEMORY_GOING_ONLINE
+ Generated before new memory becomes available in order to be able to
+ prepare subsystems to handle memory. The page allocator is still unable
+ to allocate from the new memory.
+
+MEMORY_CANCEL_ONLINE
+ Generated if MEMORY_GOING_ONLINE fails.
+
+MEMORY_ONLINE
+ Generated when memory has succesfully brought online. The callback may
+ allocate pages from the new memory.
+
+MEMORY_GOING_OFFLINE
+ Generated to begin the process of offlining memory. Allocations are no
+ longer possible from the memory but some of the memory to be offlined
+ is still in use. The callback can be used to free memory known to a
+ subsystem from the indicated memory section.
+
+MEMORY_CANCEL_OFFLINE
+ Generated if MEMORY_GOING_OFFLINE fails. Memory is available again from
+ the section that we attempted to offline.
+
+MEMORY_OFFLINE
+ Generated after offlining memory is complete.
+
+A callback routine can be registered by
+ hotplug_memory_notifier(callback_func, priority)
+
+The second argument of callback function (action) is event types of above.
+The third argument is passed by pointer of struct memory_notify.
+
+struct memory_notify {
+ unsigned long start_pfn;
+ unsigned long nr_pages;
+ int status_cahnge_nid;
+}
+
+start_pfn is start_pfn of online/offline memory.
+nr_pages is # of pages of online/offline memory.
+status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be)
+set/clear. It means a new(memoryless) node gets new memory by online and a
+node loses all memory. If this is -1, then nodemask status is not changed.
+If status_changed_nid >= 0, callback should create/discard structures for the
+node if necessary.
+
--------------
-8. Future Work
+9. Future Work
--------------
- allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
sysctl or new control file.
--
Yasunori Goto
Current memory notifier has some defects yet. (Fortunately, nothing uses it.)
This patch is to fix and rearrange for them.
- Add information of start_pfn, nr_pages, and node id if node status is
changes from/to memoryless node for callback functions.
Callbacks can't do anything without those information.
- Add notification going-online status.
It is necessary for creating per node structure before the node's
pages are available.
- Move GOING_OFFLINE status notification after page isolation.
It is good place for return memory like cache for callback,
because returned page is not used again.
- Make CANCEL events for rollingback when error occurs.
- Delete MEM_MAPPING_INVALID notification. It will be not used.
- Fix compile error of (un)register_memory_notifier().
Signed-off-by: Yasunori Goto <[email protected]>
---
drivers/base/memory.c | 9 +--------
include/linux/memory.h | 27 +++++++++++++++------------
mm/memory_hotplug.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
3 files changed, 61 insertions(+), 23 deletions(-)
Index: current/drivers/base/memory.c
===================================================================
--- current.orig/drivers/base/memory.c 2007-10-17 21:17:54.000000000 +0900
+++ current/drivers/base/memory.c 2007-10-17 21:21:30.000000000 +0900
@@ -137,7 +137,7 @@ static ssize_t show_mem_state(struct sys
return len;
}
-static inline int memory_notify(unsigned long val, void *v)
+int memory_notify(unsigned long val, void *v)
{
return blocking_notifier_call_chain(&memory_chain, val, v);
}
@@ -183,7 +183,6 @@ memory_block_action(struct memory_block
break;
case MEM_OFFLINE:
mem->state = MEM_GOING_OFFLINE;
- memory_notify(MEM_GOING_OFFLINE, NULL);
start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
ret = remove_memory(start_paddr,
PAGES_PER_SECTION << PAGE_SHIFT);
@@ -191,7 +190,6 @@ memory_block_action(struct memory_block
mem->state = old_state;
break;
}
- memory_notify(MEM_MAPPING_INVALID, NULL);
break;
default:
printk(KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
@@ -199,11 +197,6 @@ memory_block_action(struct memory_block
WARN_ON(1);
ret = -EINVAL;
}
- /*
- * For now, only notify on successful memory operations
- */
- if (!ret)
- memory_notify(action, NULL);
return ret;
}
Index: current/include/linux/memory.h
===================================================================
--- current.orig/include/linux/memory.h 2007-10-17 21:17:54.000000000 +0900
+++ current/include/linux/memory.h 2007-10-17 21:21:30.000000000 +0900
@@ -41,18 +41,15 @@ struct memory_block {
#define MEM_ONLINE (1<<0) /* exposed to userspace */
#define MEM_GOING_OFFLINE (1<<1) /* exposed to userspace */
#define MEM_OFFLINE (1<<2) /* exposed to userspace */
+#define MEM_GOING_ONLINE (1<<3)
+#define MEM_CANCEL_ONLINE (1<<4)
+#define MEM_CANCEL_OFFLINE (1<<5)
-/*
- * All of these states are currently kernel-internal for notifying
- * kernel components and architectures.
- *
- * For MEM_MAPPING_INVALID, all notifier chains with priority >0
- * are called before pfn_to_page() becomes invalid. The priority=0
- * entry is reserved for the function that actually makes
- * pfn_to_page() stop working. Any notifiers that want to be called
- * after that should have priority <0.
- */
-#define MEM_MAPPING_INVALID (1<<3)
+struct memory_notify {
+ unsigned long start_pfn;
+ unsigned long nr_pages;
+ int status_change_nid;
+};
struct notifier_block;
struct mem_section;
@@ -69,12 +66,18 @@ static inline int register_memory_notifi
static inline void unregister_memory_notifier(struct notifier_block *nb)
{
}
+static inline int memory_notify(unsigned long val, void *v)
+{
+ return 0;
+}
#else
+extern int register_memory_notifier(struct notifier_block *nb);
+extern void unregister_memory_notifier(struct notifier_block *nb);
extern int register_new_memory(struct mem_section *);
extern int unregister_memory_section(struct mem_section *);
extern int memory_dev_init(void);
extern int remove_memory_block(unsigned long, struct mem_section *, int);
-
+extern int memory_notify(unsigned long val, void *v);
#define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
Index: current/mm/memory_hotplug.c
===================================================================
--- current.orig/mm/memory_hotplug.c 2007-10-17 21:17:54.000000000 +0900
+++ current/mm/memory_hotplug.c 2007-10-17 21:21:30.000000000 +0900
@@ -187,7 +187,24 @@ int online_pages(unsigned long pfn, unsi
unsigned long onlined_pages = 0;
struct zone *zone;
int need_zonelists_rebuild = 0;
+ int nid;
+ int ret;
+ struct memory_notify arg;
+
+ arg.start_pfn = pfn;
+ arg.nr_pages = nr_pages;
+ arg.status_change_nid = -1;
+
+ nid = page_to_nid(pfn_to_page(pfn));
+ if (node_present_pages(nid) == 0)
+ arg.status_change_nid = nid;
+ ret = memory_notify(MEM_GOING_ONLINE, &arg);
+ ret = notifier_to_errno(ret);
+ if (ret) {
+ memory_notify(MEM_CANCEL_ONLINE, &arg);
+ return ret;
+ }
/*
* This doesn't need a lock to do pfn_to_page().
* The section can't be removed here because of the
@@ -222,6 +239,10 @@ int online_pages(unsigned long pfn, unsi
build_all_zonelists();
vm_total_pages = nr_free_pagecache_pages();
writeback_set_ratelimit();
+
+ if (onlined_pages)
+ memory_notify(MEM_ONLINE, &arg);
+
return 0;
}
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
@@ -467,8 +488,9 @@ int offline_pages(unsigned long start_pf
{
unsigned long pfn, nr_pages, expire;
long offlined_pages;
- int ret, drain, retry_max;
+ int ret, drain, retry_max, node;
struct zone *zone;
+ struct memory_notify arg;
BUG_ON(start_pfn >= end_pfn);
/* at least, alignment against pageblock is necessary */
@@ -480,11 +502,27 @@ int offline_pages(unsigned long start_pf
we assume this for now. .*/
if (!test_pages_in_a_zone(start_pfn, end_pfn))
return -EINVAL;
+
+ zone = page_zone(pfn_to_page(start_pfn));
+ node = zone_to_nid(zone);
+ nr_pages = end_pfn - start_pfn;
+
/* set above range as isolated */
ret = start_isolate_page_range(start_pfn, end_pfn);
if (ret)
return ret;
- nr_pages = end_pfn - start_pfn;
+
+ arg.start_pfn = start_pfn;
+ arg.nr_pages = nr_pages;
+ arg.status_change_nid = -1;
+ if (nr_pages >= node_present_pages(node))
+ arg.status_change_nid = node;
+
+ ret = memory_notify(MEM_GOING_OFFLINE, &arg);
+ ret = notifier_to_errno(ret);
+ if (ret)
+ goto failed_removal;
+
pfn = start_pfn;
expire = jiffies + timeout;
drain = 0;
@@ -539,20 +577,24 @@ repeat:
/* reset pagetype flags */
start_isolate_page_range(start_pfn, end_pfn);
/* removal success */
- zone = page_zone(pfn_to_page(start_pfn));
zone->present_pages -= offlined_pages;
zone->zone_pgdat->node_present_pages -= offlined_pages;
totalram_pages -= offlined_pages;
num_physpages -= offlined_pages;
+
vm_total_pages = nr_free_pagecache_pages();
writeback_set_ratelimit();
+
+ memory_notify(MEM_OFFLINE, &arg);
return 0;
failed_removal:
printk(KERN_INFO "memory offlining %lx to %lx failed\n",
start_pfn, end_pfn);
+ memory_notify(MEM_CANCEL_OFFLINE, &arg);
/* pushback to free area */
undo_isolate_page_range(start_pfn, end_pfn);
+
return ret;
}
#else
--
Yasunori Goto
On Thu, 18 Oct 2007 12:23:34 +0900 Yasunori Goto <[email protected]> wrote:
> writeback_set_ratelimit();
> +
> + if (onlined_pages)
> + memory_notify(MEM_ONLINE, &arg);
perhaps that open-coded writeback_set_ratelimit() should become a
notifier callback.