[PATCH V3 0/2] mm: hotplug: implement non-movable version of get_user_pages() to kill long-time pin pages

From: Lin Feng
Date: Thu Feb 21 2013 - 06:04:03 EST

Currently get_user_pages() always tries to allocate pages from movable zone,
as discussed in thread https://lkml.org/lkml/2012/11/29/69, in some case users
of get_user_pages() is easy to pin user pages for a long time(for now we found
that pages pinned as aio ring pages is such case), which is fatal for memory
hotplug/remove framework.

So the 1st patch introduces a new library function called
get_user_pages_non_movable() to pin pages only from zone non-movable in memory.
It's a wrapper of get_user_pages() but it try its best to make sure that all
pages come from non-movable zone via additional page migration. While if
migration fails, it will keep the base functionality of get_user_pages().

The 2nd patch gets around the aio ring pages can't be migrated bug caused by
get_user_pages() via using the new function. It only works when configed with
CONFIG_MEMORY_HOTREMOVE, otherwise it falls back to use the old version of

ChangeLog v2->v3:
- Handle the hugepage and THP migration bug pointed out by Mel.
- In response to the other review comments suggested by Mel.
- Updated according to mm-tree.

- Updated according to mm-tree.

ChangeLog v1->v2:
- Fix the negative return value bug pointed out by Andrew and other
suggestions pointed out by Andrew and Jeff.

- Kill the CONFIG_MEMORY_HOTREMOVE dependence suggested by Jeff.
Lin Feng (2):
mm: hotplug: implement non-movable version of get_user_pages() called
fs/aio.c: use get_user_pages_non_movable() to pin ring pages when
support memory hotremove

fs/aio.c | 4 +-
include/linux/mm.h | 14 ++++++
include/linux/mmzone.h | 4 ++
mm/memory.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++
mm/page_isolation.c | 8 ++++
5 files changed, 131 insertions(+), 2 deletions(-)

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