linux/mm/memory_hotplug.c, branch v3.16

mm, migration: add destination page freeing callback

2014-06-04T23:54:06Z

Memory migration uses a callback defined by the caller to determine how to allocate destination pages. When migration fails for a source page, however, it frees the destination page back to the system. This patch adds a memory migration callback defined by the caller to determine how to free destination pages. If a caller, such as memory compaction, builds its own freelist for migration targets, this can reuse already freed memory instead of scanning additional memory. If the caller provides a function to handle freeing of destination pages, it is called when page migration fails. If the caller passes NULL then freeing back to the system will be handled as usual. This patch introduces no functional change. Signed-off-by: David Rientjes Reviewed-by: Naoya Horiguchi Acked-by: Mel Gorman Acked-by: Vlastimil Babka Cc: Greg Thelen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: use PFN_DOWN()

2014-06-04T23:54:02Z

Replace ((x) >> PAGE_SHIFT) with the pfn macro. Signed-off-by: Fabian Frederick Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mem-hotplug: implement get/put_online_mems

2014-06-04T23:53:59Z

kmem_cache_{create,destroy,shrink} need to get a stable value of cpu/node online mask, because they init/destroy/access per-cpu/node kmem_cache parts, which can be allocated or destroyed on cpu/mem hotplug. To protect against cpu hotplug, these functions use {get,put}_online_cpus. However, they do nothing to synchronize with memory hotplug - taking the slab_mutex does not eliminate the possibility of race as described in patch 2. What we need there is something like get_online_cpus, but for memory. We already have lock_memory_hotplug, which serves for the purpose, but it's a bit of a hammer right now, because it's backed by a mutex. As a result, it imposes some limitations to locking order, which are not desirable, and can't be used just like get_online_cpus. That's why in patch 1 I substitute it with get/put_online_mems, which work exactly like get/put_online_cpus except they block not cpu, but memory hotplug. [ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by myself, because it used an rw semaphore for get/put_online_mems, making them dead lock prune. ] This patch (of 2): {un}lock_memory_hotplug, which is used to synchronize against memory hotplug, is currently backed by a mutex, which makes it a bit of a hammer - threads that only want to get a stable value of online nodes mask won't be able to proceed concurrently. Also, it imposes some strong locking ordering rules on it, which narrows down the set of its usage scenarios. This patch introduces get/put_online_mems, which are the same as get/put_online_cpus, but for memory hotplug, i.e. executing a code inside a get/put_online_mems section will guarantee a stable value of online nodes, present pages, etc. lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether. Signed-off-by: Vladimir Davydov Cc: Christoph Lameter Cc: Pekka Enberg Cc: Tang Chen Cc: Zhang Yanfei Cc: Toshi Kani Cc: Xishi Qiu Cc: Jiang Liu Cc: Rafael J. Wysocki Cc: David Rientjes Cc: Wen Congyang Cc: Yasuaki Ishimatsu Cc: Lai Jiangshan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug

2014-01-24T00:36:52Z

We don't need to do register_memory_resource() under lock_memory_hotplug() since it has its own lock and doesn't make any callbacks. Also register_memory_resource return NULL on failure so we don't have anything to cleanup at this point. The reason for this rfc is I was doing some experiments with hotplugging of memory on some of our larger systems. While it seems to work, it can be quite slow. With some preliminary digging I found that lock_memory_hotplug is clearly ripe for breakup. It could be broken up per nid or something but it also covers the online_page_callback. The online_page_callback shouldn't be very hard to break out. Also there is the issue of various structures(wmarks come to mind) that are only updated under the lock_memory_hotplug that would need to be dealt with. Cc: Tang Chen Cc: Wen Congyang Cc: Kamezawa Hiroyuki Reviewed-by: Yasuaki Ishimatsu Cc: "Rafael J. Wysocki" Cc: Hedi Cc: Mike Travis Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: print more details for bad_page()

2014-01-24T00:36:50Z

bad_page() is cool in that it prints out a bunch of data about the page. But, I can never remember which page flags are good and which are bad, or whether ->index or ->mapping is required to be NULL. This patch allows bad/dump_page() callers to specify a string about why they are dumping the page and adds explanation strings to a number of places. It also adds a 'bad_flags' argument to bad_page(), which it then dumps out separately from the flags which are actually set. This way, the messages will show specifically why the page was bad, *specifically* which flags it is complaining about, if it was a page flag combination which was the problem. [akpm@linux-foundation.org: switch to pr_alert] Signed-off-by: Dave Hansen Reviewed-by: Christoph Lameter Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: use memblock apis for early memory allocations

2014-01-22T00:19:47Z

Correct ensure_zone_is_initialized() function description according to the introduced memblock APIs for early memory allocations. Signed-off-by: Grygorii Strashko Signed-off-by: Santosh Shilimkar Cc: "Rafael J. Wysocki" Cc: Arnd Bergmann Cc: Christoph Lameter Cc: Greg Kroah-Hartman Cc: H. Peter Anvin Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: Konrad Rzeszutek Wilk Cc: Michal Hocko Cc: Paul Walmsley Cc: Pavel Machek Cc: Russell King Cc: Tejun Heo Cc: Tony Lindgren Cc: Yinghai Lu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memblock: remove unnecessary inclusions of bootmem.h

2014-01-22T00:19:46Z

Clean-up to remove depedency with bootmem headers. Signed-off-by: Grygorii Strashko Signed-off-by: Santosh Shilimkar Reviewed-by: Tejun Heo Cc: Yinghai Lu Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Cc: Christoph Lameter Cc: H. Peter Anvin Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: Konrad Rzeszutek Wilk Cc: Michal Hocko Cc: Paul Walmsley Cc: Pavel Machek Cc: Russell King Cc: Tony Lindgren Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

memblock, mem_hotplug: make memblock skip hotpluggable regions if needed

2014-01-22T00:19:45Z

Linux kernel cannot migrate pages used by the kernel. As a result, hotpluggable memory used by the kernel won't be able to be hot-removed. To solve this problem, the basic idea is to prevent memblock from allocating hotpluggable memory for the kernel at early time, and arrange all hotpluggable memory in ACPI SRAT(System Resource Affinity Table) as ZONE_MOVABLE when initializing zones. In the previous patches, we have marked hotpluggable memory regions with MEMBLOCK_HOTPLUG flag in memblock.memory. In this patch, we make memblock skip these hotpluggable memory regions in the default top-down allocation function if movable_node boot option is specified. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Tang Chen Signed-off-by: Zhang Yanfei Cc: "H. Peter Anvin" Cc: "Rafael J . Wysocki" Cc: Chen Tang Cc: Gong Chen Cc: Ingo Molnar Cc: Jiang Liu Cc: Johannes Weiner Cc: Lai Jiangshan Cc: Larry Woodman Cc: Len Brown Cc: Liu Jiang Cc: Mel Gorman Cc: Michal Nazarewicz Cc: Minchan Kim Cc: Prarit Bhargava Cc: Rik van Riel Cc: Taku Izumi Cc: Tejun Heo Cc: Thomas Gleixner Cc: Thomas Renninger Cc: Toshi Kani Cc: Vasilis Liaskovitis Cc: Wanpeng Li Cc: Wen Congyang Cc: Yasuaki Ishimatsu Cc: Yinghai Lu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mem-hotplug: introduce movable_node boot option

2013-11-13T03:09:09Z

The hot-Pluggable field in SRAT specifies which memory is hotpluggable. As we mentioned before, if hotpluggable memory is used by the kernel, it cannot be hot-removed. So memory hotplug users may want to set all hotpluggable memory in ZONE_MOVABLE so that the kernel won't use it. Memory hotplug users may also set a node as movable node, which has ZONE_MOVABLE only, so that the whole node can be hot-removed. But the kernel cannot use memory in ZONE_MOVABLE. By doing this, the kernel cannot use memory in movable nodes. This will cause NUMA performance down. And other users may be unhappy. So we need a way to allow users to enable and disable this functionality. In this patch, we introduce movable_node boot option to allow users to choose to not to consume hotpluggable memory at early boot time and later we can set it as ZONE_MOVABLE. To achieve this, the movable_node boot option will control the memblock allocation direction. That said, after memblock is ready, before SRAT is parsed, we should allocate memory near the kernel image as we explained in the previous patches. So if movable_node boot option is set, the kernel does the following: 1. After memblock is ready, make memblock allocate memory bottom up. 2. After SRAT is parsed, make memblock behave as default, allocate memory top down. Users can specify "movable_node" in kernel commandline to enable this functionality. For those who don't use memory hotplug or who don't want to lose their NUMA performance, just don't specify anything. The kernel will work as before. Signed-off-by: Tang Chen Signed-off-by: Zhang Yanfei Suggested-by: Kamezawa Hiroyuki Suggested-by: Ingo Molnar Acked-by: Tejun Heo Acked-by: Toshi Kani Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Wanpeng Li Cc: Thomas Renninger Cc: Yinghai Lu Cc: Jiang Liu Cc: Wen Congyang Cc: Lai Jiangshan Cc: Yasuaki Ishimatsu Cc: Taku Izumi Cc: Mel Gorman Cc: Michal Nazarewicz Cc: Minchan Kim Cc: Rik van Riel Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/sparsemem: use PAGES_PER_SECTION to remove redundant nr_pages parameter

2013-11-13T03:09:06Z

For below functions, - sparse_add_one_section() - kmalloc_section_memmap() - __kmalloc_section_memmap() - __kfree_section_memmap() they are always invoked to operate on one memory section, so it is redundant to always pass a nr_pages parameter, which is the page numbers in one section. So we can directly use predefined macro PAGES_PER_SECTION instead of passing the parameter. Signed-off-by: Zhang Yanfei Cc: Wen Congyang Cc: Tang Chen Cc: Toshi Kani Cc: Yasuaki Ishimatsu Cc: Yinghai Lu Cc: Yasunori Goto Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds