mirror of
https://github.com/torvalds/linux.git
synced 2024-12-24 20:01:55 +00:00
85 lines
3.0 KiB
ReStructuredText
85 lines
3.0 KiB
ReStructuredText
|
.. _memory_hotplug_notifier:
|
||
|
|
|
||
|
|
=============================
|
||
|
|
Memory hotplug event notifier
|
||
|
|
=============================
|
||
|
|
|
||
|
|
Hotplugging events are sent to a notification queue.
|
||
|
|
|
||
|
|
There are six types of notification defined in ``include/linux/memory.h``:
|
||
|
|
|
||
|
|
MEM_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.
|
||
|
|
|
||
|
|
MEM_CANCEL_ONLINE
|
||
|
|
Generated if MEM_GOING_ONLINE fails.
|
||
|
|
|
||
|
|
MEM_ONLINE
|
||
|
|
Generated when memory has successfully brought online. The callback may
|
||
|
|
allocate pages from the new memory.
|
||
|
|
|
||
|
|
MEM_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 block.
|
||
|
|
|
||
|
|
MEM_CANCEL_OFFLINE
|
||
|
|
Generated if MEM_GOING_OFFLINE fails. Memory is available again from
|
||
|
|
the memory block that we attempted to offline.
|
||
|
|
|
||
|
|
MEM_OFFLINE
|
||
|
|
Generated after offlining memory is complete.
|
||
|
|
|
||
|
|
A callback routine can be registered by calling::
|
||
|
|
|
||
|
|
hotplug_memory_notifier(callback_func, priority)
|
||
|
|
|
||
|
|
Callback functions with higher values of priority are called before callback
|
||
|
|
functions with lower values.
|
||
|
|
|
||
|
|
A callback function must have the following prototype::
|
||
|
|
|
||
|
|
int callback_func(
|
||
|
|
struct notifier_block *self, unsigned long action, void *arg);
|
||
|
|
|
||
|
|
The first argument of the callback function (self) is a pointer to the block
|
||
|
|
of the notifier chain that points to the callback function itself.
|
||
|
|
The second argument (action) is one of the event types described above.
|
||
|
|
The third argument (arg) passes a pointer of struct memory_notify::
|
||
|
|
|
||
|
|
struct memory_notify {
|
||
|
|
unsigned long start_pfn;
|
||
|
|
unsigned long nr_pages;
|
||
|
|
int status_change_nid_normal;
|
||
|
|
int status_change_nid_high;
|
||
|
|
int status_change_nid;
|
||
|
|
}
|
||
|
|
|
||
|
|
- start_pfn is start_pfn of online/offline memory.
|
||
|
|
- nr_pages is # of pages of online/offline memory.
|
||
|
|
- status_change_nid_normal is set node id when N_NORMAL_MEMORY of nodemask
|
||
|
|
is (will be) set/clear, if this is -1, then nodemask status is not changed.
|
||
|
|
- status_change_nid_high is set node id when N_HIGH_MEMORY of nodemask
|
||
|
|
is (will be) set/clear, if this is -1, then nodemask status is not changed.
|
||
|
|
- status_change_nid is set node id when N_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.
|
||
|
|
|
||
|
|
The callback routine shall return one of the values
|
||
|
|
NOTIFY_DONE, NOTIFY_OK, NOTIFY_BAD, NOTIFY_STOP
|
||
|
|
defined in ``include/linux/notifier.h``
|
||
|
|
|
||
|
|
NOTIFY_DONE and NOTIFY_OK have no effect on the further processing.
|
||
|
|
|
||
|
|
NOTIFY_BAD is used as response to the MEM_GOING_ONLINE, MEM_GOING_OFFLINE,
|
||
|
|
MEM_ONLINE, or MEM_OFFLINE action to cancel hotplugging. It stops
|
||
|
|
further processing of the notification queue.
|
||
|
|
|
||
|
|
NOTIFY_STOP stops further processing of the notification queue.
|