On Tue, May 07, 2019 at 08:38:00PM +0200, David Hildenbrand wrote:
>Only memory to be added to the buddy and to be onlined/offlined by
>user space using memory block devices needs (and should have!) memory
>block devices.
>
>Factor out creation of memory block devices Create all devices after
>arch_add_memory() succeeded. We can later drop the want_memblock parameter,
>because it is now effectively stale.
>
>Only after memory block devices have been added, memory can be onlined
>by user space. This implies, that memory is not visible to user space at
>all before arch_add_memory() succeeded.
>
>Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
>Cc: David Hildenbrand <david@xxxxxxxxxx>
>Cc: "mike.travis@xxxxxxx" <mike.travis@xxxxxxx>
>Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>Cc: Andrew Banman <andrew.banman@xxxxxxx>
>Cc: Oscar Salvador <osalvador@xxxxxxx>
>Cc: Michal Hocko <mhocko@xxxxxxxx>
>Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
>Cc: Qian Cai <cai@xxxxxx>
>Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
>Cc: Arun KS <arunks@xxxxxxxxxxxxxx>
>Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
>Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>---
> drivers/base/memory.c | 70 ++++++++++++++++++++++++++----------------
> include/linux/memory.h | 2 +-
> mm/memory_hotplug.c | 15 ++++-----
> 3 files changed, 53 insertions(+), 34 deletions(-)
>
>diff --git a/drivers/base/memory.c b/drivers/base/memory.c
>index 6e0cb4fda179..862c202a18ca 100644
>--- a/drivers/base/memory.c
>+++ b/drivers/base/memory.c
>@@ -701,44 +701,62 @@ static int add_memory_block(int base_section_nr)
> return 0;
> }
>
>+static void unregister_memory(struct memory_block *memory)
>+{
>+ BUG_ON(memory->dev.bus != &memory_subsys);
>+
>+ /* drop the ref. we got via find_memory_block() */
>+ put_device(&memory->dev);
>+ device_unregister(&memory->dev);
>+}
>+
> /*
>- * need an interface for the VM to add new memory regions,
>- * but without onlining it.
>+ * Create memory block devices for the given memory area. Start and size
>+ * have to be aligned to memory block granularity. Memory block devices
>+ * will be initialized as offline.
> */
>-int hotplug_memory_register(int nid, struct mem_section *section)
>+int hotplug_memory_register(unsigned long start, unsigned long size)
One trivial suggestion about the function name.
For memory_block device, sometimes we use the full name
find_memory_block
init_memory_block
add_memory_block
But sometimes we use *nick* name
hotplug_memory_register
register_memory
unregister_memory
This is a little bit confusion.
Can we use one name convention here?
[...]
> /*
>@@ -1106,6 +1100,13 @@ int __ref add_memory_resource(int nid, struct resource *res)
> if (ret < 0)
> goto error;
>
>+ /* create memory block devices after memory was added */
>+ ret = hotplug_memory_register(start, size);
>+ if (ret) {
>+ arch_remove_memory(nid, start, size, NULL);
Functionally, it works I think.
But arch_remove_memory() would remove pages from zone. At this point, we just
allocate section/mmap for pages, the zones are empty and pages are not
connected to zone.
Function zone = page_zone(page); always gets zone #0, since pages->flags is 0
at this point. This is not exact.
Would we add some comment to mention this? Or we need to clean up
arch_remove_memory() to take out __remove_zone()?
>+ goto error;
>+ }
>+
> if (new_node) {
> /* If sysfs file of new node can't be created, cpu on the node
> * can't be hot-added. There is no rollback way now.
>--
>2.20.1
--
Wei Yang
Help you, Help me
