linux.git/mm/migrate.c, branch v5.11

mm: migrate: do not migrate HugeTLB page whose refcount is one

2021-02-05T19:03:47+00:00

All pages isolated for the migration have an elevated reference count and
therefore seeing a reference count equal to 1 means that the last user of
the page has dropped the reference and the page has became unused and
there doesn't make much sense to migrate it anymore.

This has been done for regular pages and this patch does the same for
hugetlb pages.  Although the likelihood of the race is rather small for
hugetlb pages it makes sense the two code paths in sync.

Link: https://lkml.kernel.org/r/20210115124942.46403-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Reviewed-by: Mike Kravetz 
Acked-by: Yang Shi 
Acked-by: Michal Hocko 
Reviewed-by: David Hildenbrand 
Reviewed-by: Oscar Salvador 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix numa stats for thp migration

2021-01-24T17:20:52+00:00

Currently the kernel is not correctly updating the numa stats for
NR_FILE_PAGES and NR_SHMEM on THP migration.  Fix that.

For NR_FILE_DIRTY and NR_ZONE_WRITE_PENDING, although at the moment
there is no need to handle THP migration as kernel still does not have
write support for file THP but to be more future proof, this patch adds
the THP support for those stats as well.

Link: https://lkml.kernel.org/r/20210108155813.2914586-2-shakeelb@google.com
Fixes: e71769ae52609 ("mm: enable thp migration for shmem thp")
Signed-off-by: Shakeel Butt 
Acked-by: Yang Shi 
Reviewed-by: Roman Gushchin 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcg: fix memcg file_dirty numa stat

2021-01-24T17:20:52+00:00

The kernel updates the per-node NR_FILE_DIRTY stats on page migration
but not the memcg numa stats.

That was not an issue until recently the commit 5f9a4f4a7096 ("mm:
memcontrol: add the missing numa_stat interface for cgroup v2") exposed
numa stats for the memcg.

So fix the file_dirty per-memcg numa stat.

Link: https://lkml.kernel.org/r/20210108155813.2914586-1-shakeelb@google.com
Fixes: 5f9a4f4a7096 ("mm: memcontrol: add the missing numa_stat interface for cgroup v2")
Signed-off-by: Shakeel Butt 
Reviewed-by: Muchun Song 
Acked-by: Yang Shi 
Reviewed-by: Roman Gushchin 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix some spelling mistakes in comments

2020-12-16T06:46:19+00:00

Fix some spelling mistakes in comments:
	udpate ==> update
	succesful ==> successful
	exmaple ==> example
	unneccessary ==> unnecessary
	stoping ==> stopping
	uknown ==> unknown

Link: https://lkml.kernel.org/r/20201127011747.86005-1-shihaitao1@huawei.com
Signed-off-by: Haitao Shi 
Reviewed-by: Mike Rapoport 
Reviewed-by: Souptick Joarder 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: remove unused parameter in migrate_vma_insert_page()

2020-12-15T20:13:46+00:00

"dst" parameter to migrate_vma_insert_page() is not used anymore.

Link: https://lkml.kernel.org/r/CANubcdUwCAMuUyamG2dkWP=cqSR9MAS=tHLDc95kQkqU-rEnAg@mail.gmail.com
Signed-off-by: Stephen Zhang 
Reviewed-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: return -ENOSYS if THP migration is unsupported

2020-12-15T20:13:45+00:00

In the current implementation unmap_and_move() would return -ENOMEM if THP
migration is unsupported, then the THP will be split.  If split is failed
just exit without trying to migrate other pages.  It doesn't make too much
sense since there may be enough free memory to migrate other pages and
there may be a lot base pages on the list.

Return -ENOSYS to make consistent with hugetlb.  And if THP split is
failed just skip and try other pages on the list.

Just skip the whole list and exit when free memory is really low.

Link: https://lkml.kernel.org/r/20201113205359.556831-6-shy828301@gmail.com
Signed-off-by: Yang Shi 
Cc: Jan Kara 
Cc: Matthew Wilcox 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Song Liu 
Cc: Zi Yan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: clean up migrate_prep{_local}

2020-12-15T20:13:45+00:00

The migrate_prep{_local} never fails, so it is pointless to have return
value and check the return value.

Link: https://lkml.kernel.org/r/20201113205359.556831-5-shy828301@gmail.com
Signed-off-by: Yang Shi 
Reviewed-by: Zi Yan 
Cc: Jan Kara 
Cc: Matthew Wilcox 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Song Liu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: skip shared exec THP for NUMA balancing

2020-12-15T20:13:45+00:00

The NUMA balancing skip shared exec base page.  Since
CONFIG_READ_ONLY_THP_FOR_FS was introduced, there are probably shared exec
THP, so skip such THPs for NUMA balancing as well.

And Willy's regular filesystem THP support patches could create shared
exec THP wven without that config.

In addition, the page_is_file_lru() is used to tell if the page is file
cache or not, but it filters out shmem page.  It sounds like a typical
usecase by putting executables in shmem to achieve performance gain via
using shmem-THP, so it sounds worth skipping migration for such case too.

Link: https://lkml.kernel.org/r/20201113205359.556831-4-shy828301@gmail.com
Signed-off-by: Yang Shi 
Cc: Matthew Wilcox 
Cc: Jan Kara 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Song Liu 
Cc: Zi Yan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: migrate: simplify the logic for handling permanent failure

2020-12-15T20:13:45+00:00

When unmap_and_move{_huge_page}() returns !-EAGAIN and
!MIGRATEPAGE_SUCCESS, the page would be put back to LRU or proper list if
it is non-LRU movable page.  But, the callers always call
putback_movable_pages() to put the failed pages back later on, so it seems
not very efficient to put every single page back immediately, and the code
looks convoluted.

Put the failed page on a separate list, then splice the list to migrate
list when all pages are tried.  It is the caller's responsibility to call
putback_movable_pages() to handle failures.  This also makes the code
simpler and more readable.

After the change the rules are:
    * Success: non hugetlb page will be freed, hugetlb page will be put
               back
    * -EAGAIN: stay on the from list
    * -ENOMEM: stay on the from list
    * Other errno: put on ret_pages list then splice to from list

The from list would be empty iff all pages are migrated successfully, it
was not so before.  This has no impact to current existing callsites.

Link: https://lkml.kernel.org/r/20201113205359.556831-3-shy828301@gmail.com
Signed-off-by: Yang Shi 
Reviewed-by: Zi Yan 
Cc: Jan Kara 
Cc: Matthew Wilcox 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Song Liu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: truncate_complete_page() does not exist any more

2020-12-15T20:13:45+00:00

Patch series "mm: misc migrate cleanup and improvement", v3.

This patch (of 5):

The commit 9f4e41f4717832e ("mm: refactor truncate_complete_page()")
refactored truncate_complete_page(), and it is not existed anymore,
correct the comment in vmscan and migrate to avoid confusion.

Link: https://lkml.kernel.org/r/20201113205359.556831-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20201113205359.556831-2-shy828301@gmail.com
Signed-off-by: Yang Shi 
Reviewed-by: Jan Kara 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Song Liu 
Cc: Mel Gorman 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds