At 2012/7/23 19:06, Vasilis Liaskovitis Wrote:
Hi,
On Mon, Jul 23, 2012 at 05:08:04PM +0800, Wen Congyang wrote:
+static int memblock_state_notifier_nb(struct notifier_block *nb, unsigned long
+ val, void *v)
+{
+ struct memory_notify *arg = (struct memory_notify *)v;
+ struct memory_block *mem = NULL;
+ struct mem_section *ms;
+ unsigned long section_nr;
+
+ section_nr = pfn_to_section_nr(arg->start_pfn);
+ ms = __nr_to_section(section_nr);
+ mem = find_memory_block(ms);
+ if (!mem)
+ goto out;
we may offline more than one memory block.
thanks, you are right.
+
+ switch (val) {
+ case MEM_GOING_OFFLINE:
+ case MEM_OFFLINE:
+ case MEM_GOING_ONLINE:
+ case MEM_ONLINE:
+ case MEM_CANCEL_ONLINE:
+ case MEM_CANCEL_OFFLINE:
+ mem->state = val;
mem->state is protected by the lock mem->state_mutex, so if you want to
update the state, you must lock mem->state_mutex. But you cannot lock it
here, because it may cause deadlock:
acpi_memhotplug sysfs interface
===============================================================================
memory_block_change_state()
lock mem->state_mutex
memory_block_action()
offline_pages()
lock_memory_hotplug()
offline_memory()
lock_memory_hotplug() //
block
memory_notify()
memblock_state_notifier_nb()
===============================================================================
good point. Maybe if memory_hotplug_lock and state_mutex locks are acquired in
the same order in the 2 code paths, this could be avoided.
Yes, I am trying to fix another 2 problems(also based on ishimatsu's
patchset):
1. offline_memory() will fail if part of the memory is onlined and part
of the memory
is offlined.
2. notify the userspace if the memory block's status is changed
I guess this problem can be fixed together.
Thanks
Wen Congyang
I'm writing another patch to fix it.
ok, I 'll test.
thanks,
- Vasilis
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