Recently, I got many reports about perfermance degradation in embedded system(Android mobile phone, webOS TV and so on) and easy fork fail.
The problem was fragmentation caused by zram and GPU driver mainly. With memory pressure, their pages were spread out all of pageblock and it cannot be migrated with current compaction algorithm which supports only LRU pages. In the end, compaction cannot work well so reclaimer shrinks all of working set pages. It made system very slow and even to fail to fork easily which requires order-[2 or 3] allocations.
Other pain point is that they cannot use CMA memory space so when OOM kill happens, I can see many free pages in CMA area, which is not memory efficient. In our product which has big CMA memory, it reclaims zones too exccessively to allocate GPU and zram page although there are lots of free space in CMA so system becomes very slow easily.
To solve these problem, this patch tries to add facility to migrate non-lru pages via introducing new functions and page flags to help migration.
struct address_space_operations { .. .. bool (*isolate_page)(struct page *, isolate_mode_t); void (*putback_page)(struct page *); .. }
new page flags
PG_movable PG_isolated
For details, please read description in "mm: migrate: support non-lru movable page migration".
Originally, Gioh Kim had tried to support this feature but he moved so I took over the work. I took many code from his work and changed a little bit and Konstantin Khlebnikov helped Gioh a lot so he should deserve to have many credit, too.
And I should mention Chulmin who have tested this patchset heavily so I can find many bugs from him. :)
Thanks, Gioh, Konstantin and Chulmin!
This patchset consists of five parts.
1. clean up migration mm: use put_page to free page instead of putback_lru_page
2. add non-lru page migration feature mm: migrate: support non-lru movable page migration
3. rework KVM memory-ballooning mm: balloon: use general non-lru movable page feature
4. zsmalloc refactoring for preparing page migration zsmalloc: keep max_object in size_class zsmalloc: use bit_spin_lock zsmalloc: use accessor zsmalloc: factor page chain functionality out zsmalloc: introduce zspage structure zsmalloc: separate free_zspage from putback_zspage zsmalloc: use freeobj for index
5. zsmalloc page migration zsmalloc: page migration support zram: use __GFP_MOVABLE for memory allocation
* From v5 * rebase on next-20160520 * move utility functions to compaction.c and export - Sergey * zsmalloc dobule free fix - Sergey * add additional Reviewed-by for zsmalloc - Sergey
* From v4 * rebase on mmotm-2016-05-05-17-19 * fix huge object migration - Chulmin * !CONFIG_COMPACTION support for zsmalloc
* From v3 * rebase on mmotm-2016-04-06-20-40 * fix swap_info deadlock - Chulmin * race without page_lock - Vlastimil * no use page._mapcount for potential user-mapped page driver - Vlastimil * fix and enhance doc/description - Vlastimil * use page->mapping lower bits to represent PG_movable * make driver side's rule simple.
* From v2 * rebase on mmotm-2016-03-29-15-54-16 * check PageMovable before lock_page - Joonsoo * check PageMovable before PageIsolated checking - Joonsoo * add more description about rule
* From v1 * rebase on v4.5-mmotm-2016-03-17-15-04 * reordering patches to merge clean-up patches first * add Acked-by/Reviewed-by from Vlastimil and Sergey * use each own mount model instead of reusing anon_inode_fs - Al Viro * small changes - YiPing, Gioh
Cc: Vlastimil Babka vbabka@suse.cz Cc: dri-devel@lists.freedesktop.org Cc: Hugh Dickins hughd@google.com Cc: John Einar Reitan john.reitan@foss.arm.com Cc: Jonathan Corbet corbet@lwn.net Cc: Joonsoo Kim iamjoonsoo.kim@lge.com Cc: Konstantin Khlebnikov koct9i@gmail.com Cc: Mel Gorman mgorman@suse.de Cc: Naoya Horiguchi n-horiguchi@ah.jp.nec.com Cc: Rafael Aquini aquini@redhat.com Cc: Rik van Riel riel@redhat.com Cc: Sergey Senozhatsky sergey.senozhatsky@gmail.com Cc: virtualization@lists.linux-foundation.org Cc: Gioh Kim gi-oh.kim@profitbricks.com Cc: Chan Gyun Jeong chan.jeong@lge.com Cc: Sangseok Lee sangseok.lee@lge.com Cc: Kyeongdon Kim kyeongdon.kim@lge.com Cc: Chulmin Kim cmlaika.kim@samsung.com
Minchan Kim (12): mm: use put_page to free page instead of putback_lru_page mm: migrate: support non-lru movable page migration mm: balloon: use general non-lru movable page feature zsmalloc: keep max_object in size_class zsmalloc: use bit_spin_lock zsmalloc: use accessor zsmalloc: factor page chain functionality out zsmalloc: introduce zspage structure zsmalloc: separate free_zspage from putback_zspage zsmalloc: use freeobj for index zsmalloc: page migration support zram: use __GFP_MOVABLE for memory allocation
Documentation/filesystems/Locking | 4 + Documentation/filesystems/vfs.txt | 11 + Documentation/vm/page_migration | 107 ++- drivers/block/zram/zram_drv.c | 6 +- drivers/virtio/virtio_balloon.c | 54 +- include/linux/balloon_compaction.h | 53 +- include/linux/compaction.h | 17 + include/linux/fs.h | 2 + include/linux/ksm.h | 3 +- include/linux/migrate.h | 2 + include/linux/mm.h | 1 + include/linux/page-flags.h | 33 +- include/uapi/linux/magic.h | 2 + mm/balloon_compaction.c | 94 +-- mm/compaction.c | 76 +- mm/ksm.c | 4 +- mm/migrate.c | 256 +++++-- mm/page_alloc.c | 2 +- mm/util.c | 6 +- mm/vmscan.c | 2 +- mm/zsmalloc.c | 1351 +++++++++++++++++++++++++----------- 21 files changed, 1475 insertions(+), 611 deletions(-)