On 06/15/2015 09:50 AM, Konstantin Khlebnikov wrote:
This is incomplete implementation of non-isolating memory migration and
compaction. It's alive!
The main reason -- it can preserve lru order during compaction.
That's nice, and there's also another benefit - no lru_lock taken during
migration scanner.
So I think it's worth pursuing. But after brief checking, I'm not sure
it can work as it is (but maybe I just overlooked something). What
prevents somebody else to isolate the old page from the lru while you
are migrating it? Especially in Patch 6, it appears that a PageLRU() is
tested without any lock and only then insert_lru_page() takes the
lru_lock to do something. This seems racy to me.
Also it makes implementation of migration for various types of pages: zram,
balloon, ptes, kernel stacks [ Why not? I've already migrated them accidentally
and kernel have crashed in very funny places ] much easier: owner just have to
set page->mappingw with valid method a_ops->migratepage.
---
Konstantin Khlebnikov (6):
pagevec: segmented page vectors
mm/migrate: move putback of old page out of unmap_and_move
mm/cma: repalce reclaim_clean_pages_from_list with try_to_reclaim_page
mm/migrate: page migration without page isolation
mm/compaction: use migration without isolation
mm/migrate: preserve lru order if possible
include/linux/migrate.h | 4 +
include/linux/mm.h | 1
include/linux/pagevec.h | 48 ++++++++-
include/trace/events/compaction.h | 12 +-
mm/compaction.c | 205 +++++++++++++++++++++----------------
mm/filemap.c | 20 ++++
mm/internal.h | 12 +-
mm/migrate.c | 141 +++++++++++++++++++++----
mm/page_alloc.c | 35 ++++--
mm/swap.c | 69 ++++++++++++
mm/vmscan.c | 42 +-------
11 files changed, 410 insertions(+), 179 deletions(-)
--
Konstantin
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