Messages in this thread | | | Date | Mon, 23 Jul 2012 20:13:34 +0800 | From | Wen Congyang <> | Subject | Re: [RFC PATCH] memory-hotplug: Add memblock_state notifier |
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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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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