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SubjectRe: [PATCH 1/5] generic __remove_pages() support

Badari-san.

> Index: linux-2.6.25-rc2/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.25-rc2.orig/mm/memory_hotplug.c 2008-02-27 12:58:17.000000000 -0800
> +++ linux-2.6.25-rc2/mm/memory_hotplug.c 2008-02-27 16:06:50.000000000 -0800
> @@ -102,6 +102,21 @@ static int __add_section(struct zone *zo
> return register_new_memory(__pfn_to_section(phys_start_pfn));
> }
>
> +static int __remove_section(struct zone *zone, struct mem_section *ms)
> +{
> + int ret = -EINVAL;
> +
> + if (!valid_section(ms))
> + return ret;
> +
> + ret = unregister_memory_section(ms);
> + if (ret)
> + return ret;
> +
> + sparse_remove_one_section(zone, ms);
> + return 0;
> +}
> +
> /*
> * Reasonably generic function for adding memory. It is
> * expected that archs that support memory hotplug will
> @@ -135,6 +150,35 @@ int __add_pages(struct zone *zone, unsig
> }
> EXPORT_SYMBOL_GPL(__add_pages);
>
> +int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> + unsigned long nr_pages)
> +{
> + unsigned long i, ret = 0;
> + int sections_to_remove;
> + unsigned long flags;
> + struct pglist_data *pgdat = zone->zone_pgdat;
> +
> + /*
> + * We can only remove entire sections
> + */
> + BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
> + BUG_ON(nr_pages % PAGES_PER_SECTION);
> +
> + release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
> +
> + sections_to_remove = nr_pages / PAGES_PER_SECTION;
> + for (i = 0; i < sections_to_remove; i++) {
> + unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
> + pgdat_resize_lock(pgdat, &flags);
> + ret = __remove_section(zone, __pfn_to_section(pfn));
> + pgdat_resize_unlock(pgdat, &flags);
> + if (ret)
> + break;
> + }
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(__remove_pages);

Here may be a bug.
__remove_section() is called with pgdat_resize_lock() which is
spin_lock_irqsave().

__remove_section()
|
+--> unregister_memory_section()
|
+--> remove_memory_block()
|
+--> unregister_memory()
|
+--> sysdev_unregister()

sysdev_unregister() calls mutex_lock().
It might sleep with irq disable, right?
I found BUG()'s messages by this.

Bye.

--
Yasunori Goto




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