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Commit 242831eb authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

Memory hotplug / ACPI: Simplify memory removal 



Now that the memory offlining should be taken care of by the
companion device offlining code in acpi_scan_hot_remove(), the
ACPI memory hotplug driver doesn't need to offline it in
remove_memory() any more.  Moreover, since the return value of
remove_memory() is not used, it's better to make it be a void
function and trigger a BUG() if the memory scheduled for removal is
not offline.

Change the code in accordance with the above observations.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarToshi Kani <toshi.kani@hp.com>
parent 303bfdb1

drivers/acpi/acpi_memhotplug.c

+3 −10
Original line number Diff line number Diff line
@@ -271,13 +271,11 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device) 
	return 0;

}



static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)

static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)

{

	acpi_handle handle = mem_device->device->handle;

	int result = 0, nid;

	struct acpi_memory_info *info, *n;



	nid = acpi_get_node(handle);

	int nid = acpi_get_node(handle);



	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {

		if (!info->enabled)
@@ -287,15 +285,10 @@ static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device) 
			nid = memory_add_physaddr_to_nid(info->start_addr);



		acpi_unbind_memory_blocks(info, handle);

		result = remove_memory(nid, info->start_addr, info->length);

		if (result)

			return result;



		remove_memory(nid, info->start_addr, info->length);

		list_del(&info->list);

		kfree(info);

	}



	return result;

}



static void acpi_memory_device_free(struct acpi_memory_device *mem_device)

include/linux/memory_hotplug.h

+1 −1
Original line number Diff line number Diff line
@@ -252,7 +252,7 @@ extern int add_memory(int nid, u64 start, u64 size); 
extern int arch_add_memory(int nid, u64 start, u64 size);

extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);

extern bool is_memblock_offlined(struct memory_block *mem);

extern int remove_memory(int nid, u64 start, u64 size);

extern void remove_memory(int nid, u64 start, u64 size);

extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,

								int nr_pages);

extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);

mm/memory_hotplug.c

+8 −63
Original line number Diff line number Diff line
@@ -1670,24 +1670,6 @@ int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn, 
}



#ifdef CONFIG_MEMORY_HOTREMOVE

/**

 * offline_memory_block_cb - callback function for offlining memory block

 * @mem: the memory block to be offlined

 * @arg: buffer to hold error msg

 *

 * Always return 0, and put the error msg in arg if any.

 */

static int offline_memory_block_cb(struct memory_block *mem, void *arg)

{

	int *ret = arg;

	int error = device_offline(&mem->dev);



	if (error != 0 && *ret == 0)

		*ret = error;



	return 0;

}



static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)

{

	int ret = !is_memblock_offlined(mem);
@@ -1813,54 +1795,22 @@ void try_offline_node(int nid) 
}

EXPORT_SYMBOL(try_offline_node);



int __ref remove_memory(int nid, u64 start, u64 size)

void __ref remove_memory(int nid, u64 start, u64 size)

{

	unsigned long start_pfn, end_pfn;

	int ret = 0;

	int retry = 1;



	start_pfn = PFN_DOWN(start);

	end_pfn = PFN_UP(start + size - 1);



	/*

	 * When CONFIG_MEMCG is on, one memory block may be used by other

	 * blocks to store page cgroup when onlining pages. But we don't know

	 * in what order pages are onlined. So we iterate twice to offline

	 * memory:

	 * 1st iterate: offline every non primary memory block.

	 * 2nd iterate: offline primary (i.e. first added) memory block.

	 */

repeat:

	walk_memory_range(start_pfn, end_pfn, &ret,

			  offline_memory_block_cb);

	if (ret) {

		if (!retry)

			return ret;



		retry = 0;

		ret = 0;

		goto repeat;

	}

	int ret;



	lock_memory_hotplug();



	/*

	 * we have offlined all memory blocks like this:

	 *   1. lock memory hotplug

	 *   2. offline a memory block

	 *   3. unlock memory hotplug

	 *

	 * repeat step1-3 to offline the memory block. All memory blocks

	 * must be offlined before removing memory. But we don't hold the

	 * lock in the whole operation. So we should check whether all

	 * memory blocks are offlined.

	 * All memory blocks must be offlined before removing memory.  Check

	 * whether all memory blocks in question are offline and trigger a BUG()

	 * if this is not the case.

	 */



	ret = walk_memory_range(start_pfn, end_pfn, NULL,

	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,

				is_memblock_offlined_cb);

	if (ret) {

		unlock_memory_hotplug();

		return ret;

		BUG();

	}



	/* remove memmap entry */
@@ -1871,17 +1821,12 @@ int __ref remove_memory(int nid, u64 start, u64 size) 
	try_offline_node(nid);



	unlock_memory_hotplug();



	return 0;

}

#else

int offline_pages(unsigned long start_pfn, unsigned long nr_pages)

{

	return -EINVAL;

}

int remove_memory(int nid, u64 start, u64 size)

{

	return -EINVAL;

}

void remove_memory(int nid, u64 start, u64 size) {}

#endif /* CONFIG_MEMORY_HOTREMOVE */

EXPORT_SYMBOL_GPL(remove_memory);