linux.git/mm/migrate.c, branch v5.9

mm/migrate: correct thp migration stats

2020-09-26T17:33:57+00:00

PageTransHuge returns true for both thp and hugetlb, so thp stats was
counting both thp and hugetlb migrations.  Exclude hugetlb migration by
setting is_thp variable right.

Clean up thp handling code too when we are there.

Fixes: 1a5bae25e3cf ("mm/vmstat: add events for THP migration without split")
Signed-off-by: Zi Yan 
Signed-off-by: Andrew Morton 
Reviewed-by: Daniel Jordan 
Cc: Anshuman Khandual 
Link: https://lkml.kernel.org/r/20200917210413.1462975-1-zi.yan@sent.com
Signed-off-by: Linus Torvalds

mm: migration of hugetlbfs page skip memcg

2020-09-19T20:13:38+00:00

hugetlbfs pages do not participate in memcg: so although they do find most
of migrate_page_states() useful, it would be better if they did not call
into mem_cgroup_migrate() - where Qian Cai reported that LTP's
move_pages12 triggers the warning in Alex Shi's prospective commit
"mm/memcg: warning on !memcg after readahead page charged".

Signed-off-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Reviewed-by: Shakeel Butt 
Acked-by: Johannes Weiner 
Cc: Alex Shi 
Cc: Michal Hocko 
Cc: Mike Kravetz 
Cc: Qian Cai 
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301359460.5954@eggly.anvils
Signed-off-by: Linus Torvalds

mm/migrate: preserve soft dirty in remove_migration_pte()

2020-09-05T19:14:30+00:00

The code to remove a migration PTE and replace it with a device private
PTE was not copying the soft dirty bit from the migration entry.  This
could lead to page contents not being marked dirty when faulting the page
back from device private memory.

Signed-off-by: Ralph Campbell 
Signed-off-by: Andrew Morton 
Reviewed-by: Christoph Hellwig 
Cc: Jerome Glisse 
Cc: Alistair Popple 
Cc: Christoph Hellwig 
Cc: Jason Gunthorpe 
Cc: Bharata B Rao 
Link: https://lkml.kernel.org/r/20200831212222.22409-3-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds

mm/migrate: remove unnecessary is_zone_device_page() check

2020-09-05T19:14:30+00:00

Patch series "mm/migrate: preserve soft dirty in remove_migration_pte()".

I happened to notice this from code inspection after seeing Alistair
Popple's patch ("mm/rmap: Fixup copying of soft dirty and uffd ptes").

This patch (of 2):

The check for is_zone_device_page() and is_device_private_page() is
unnecessary since the latter is sufficient to determine if the page is a
device private page.  Simplify the code for easier reading.

Signed-off-by: Ralph Campbell 
Signed-off-by: Andrew Morton 
Reviewed-by: Christoph Hellwig 
Cc: Jerome Glisse 
Cc: Alistair Popple 
Cc: Christoph Hellwig 
Cc: Jason Gunthorpe 
Cc: Bharata B Rao 
Link: https://lkml.kernel.org/r/20200831212222.22409-1-rcampbell@nvidia.com
Link: https://lkml.kernel.org/r/20200831212222.22409-2-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds

mm/rmap: fixup copying of soft dirty and uffd ptes

2020-09-05T19:14:30+00:00

During memory migration a pte is temporarily replaced with a migration
swap pte.  Some pte bits from the existing mapping such as the soft-dirty
and uffd write-protect bits are preserved by copying these to the
temporary migration swap pte.

However these bits are not stored at the same location for swap and
non-swap ptes.  Therefore testing these bits requires using the
appropriate helper function for the given pte type.

Unfortunately several code locations were found where the wrong helper
function is being used to test soft_dirty and uffd_wp bits which leads to
them getting incorrectly set or cleared during page-migration.

Fix these by using the correct tests based on pte type.

Fixes: a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in migration")
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple 
Signed-off-by: Andrew Morton 
Reviewed-by: Peter Xu 
Cc: Jérôme Glisse 
Cc: John Hubbard 
Cc: Ralph Campbell 
Cc: Alistair Popple 
Cc: 
Link: https://lkml.kernel.org/r/20200825064232.10023-2-alistair@popple.id.au
Signed-off-by: Linus Torvalds

mm/migrate: fixup setting UFFD_WP flag

2020-09-05T19:14:30+00:00

Commit f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration")
introduced support for tracking the uffd wp bit during page migration.
However the non-swap PTE variant was used to set the flag for zone device
private pages which are a type of swap page.

This leads to corruption of the swap offset if the original PTE has the
uffd_wp flag set.

Fixes: f45ec5ff16a75 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple 
Signed-off-by: Andrew Morton 
Reviewed-by: Peter Xu 
Cc: Jérôme Glisse 
Cc: John Hubbard 
Cc: Ralph Campbell 
Link: https://lkml.kernel.org/r/20200825064232.10023-1-alistair@popple.id.au
Signed-off-by: Linus Torvalds

mm: replace hpage_nr_pages with thp_nr_pages

2020-08-15T02:56:56+00:00

The thp prefix is more frequently used than hpage and we should be
consistent between the various functions.

[akpm@linux-foundation.org: fix mm/migrate.c]

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: William Kucharski 
Reviewed-by: Zi Yan 
Cc: Mike Kravetz 
Cc: David Hildenbrand 
Cc: "Kirill A. Shutemov" 
Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org
Signed-off-by: Linus Torvalds

mm/mempolicy: use a standard migration target allocation callback

2020-08-12T17:58:02+00:00

There is a well-defined migration target allocation callback.  Use it.

Signed-off-by: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Acked-by: Michal Hocko 
Acked-by: Vlastimil Babka 
Cc: Christoph Hellwig 
Cc: Mike Kravetz 
Cc: Naoya Horiguchi 
Cc: Roman Gushchin 
Link: http://lkml.kernel.org/r/1594622517-20681-7-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds

mm/migrate: introduce a standard migration target allocation function

2020-08-12T17:58:02+00:00

There are some similar functions for migration target allocation.  Since
there is no fundamental difference, it's better to keep just one rather
than keeping all variants.  This patch implements base migration target
allocation function.  In the following patches, variants will be converted
to use this function.

Changes should be mechanical, but, unfortunately, there are some
differences.  First, some callers' nodemask is assgined to NULL since NULL
nodemask will be considered as all available nodes, that is,
&node_states[N_MEMORY].  Second, for hugetlb page allocation, gfp_mask is
redefined as regular hugetlb allocation gfp_mask plus __GFP_THISNODE if
user provided gfp_mask has it.  This is because future caller of this
function requires to set this node constaint.  Lastly, if provided nodeid
is NUMA_NO_NODE, nodeid is set up to the node where migration source
lives.  It helps to remove simple wrappers for setting up the nodeid.

Note that PageHighmem() call in previous function is changed to open-code
"is_highmem_idx()" since it provides more readability.

[akpm@linux-foundation.org: tweak patch title, per Vlastimil]
[akpm@linux-foundation.org: fix typo in comment]

Signed-off-by: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Acked-by: Vlastimil Babka 
Acked-by: Michal Hocko 
Cc: Christoph Hellwig 
Cc: Mike Kravetz 
Cc: Naoya Horiguchi 
Cc: Roman Gushchin 
Link: http://lkml.kernel.org/r/1594622517-20681-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds

mm/migrate: clear __GFP_RECLAIM to make the migration callback consistent with regular THP allocations

2020-08-12T17:58:02+00:00

new_page_nodemask is a migration callback and it tries to use a common gfp
flags for the target page allocation whether it is a base page or a THP.
The later only adds GFP_TRANSHUGE to the given mask.  This results in the
allocation being slightly more aggressive than necessary because the
resulting gfp mask will contain also __GFP_RECLAIM_KSWAPD.  THP
allocations usually exclude this flag to reduce over eager background
reclaim during a high THP allocation load which has been seen during large
mmaps initialization.  There is no indication that this is a problem for
migration as well but theoretically the same might happen when migrating
large mappings to a different node.  Make the migration callback
consistent with regular THP allocations.

[akpm@linux-foundation.org: fix comment typo, per Vlastimil]

Signed-off-by: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Acked-by: Michal Hocko 
Acked-by: Vlastimil Babka 
Cc: Christoph Hellwig 
Cc: Mike Kravetz 
Cc: Naoya Horiguchi 
Cc: Roman Gushchin 
Link: http://lkml.kernel.org/r/1594622517-20681-5-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds