linux.git/mm/rmap.c, branch v4.18

mm: do not drop unused pages when userfaultd is running

2018-07-14T18:11:09+00:00

KVM guests on s390 can notify the host of unused pages.  This can result
in pte_unused callbacks to be true for KVM guest memory.

If a page is unused (checked with pte_unused) we might drop this page
instead of paging it.  This can have side-effects on userfaultd, when
the page in question was already migrated:

The next access of that page will trigger a fault and a user fault
instead of faulting in a new and empty zero page.  As QEMU does not
expect a userfault on an already migrated page this migration will fail.

The most straightforward solution is to ignore the pte_unused hint if a
userfault context is active for this VMA.

Link: http://lkml.kernel.org/r/20180703171854.63981-1-borntraeger@de.ibm.com
Signed-off-by: Christian Borntraeger 
Cc: Martin Schwidefsky 
Cc: Andrea Arcangeli 
Cc: Mike Rapoport 
Cc: Janosch Frank 
Cc: David Hildenbrand 
Cc: Cornelia Huck 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'v4.17-rc2' into docs-next

2018-04-27T23:13:20+00:00

  Merge -rc2 to pick up the changes to
  Documentation/core-api/kernel-api.rst that hit mainline via the
  networking tree.  In their absence, subsequent patches cannot be
  applied.

mm: enable thp migration for shmem thp

2018-04-21T00:18:35+00:00

My testing for the latest kernel supporting thp migration showed an
infinite loop in offlining the memory block that is filled with shmem
thps.  We can get out of the loop with a signal, but kernel should return
with failure in this case.

What happens in the loop is that scan_movable_pages() repeats returning
the same pfn without any progress.  That's because page migration always
fails for shmem thps.

In memory offline code, memory blocks containing unmovable pages should be
prevented from being offline targets by has_unmovable_pages() inside
start_isolate_page_range().  So it's possible to change migratability for
non-anonymous thps to avoid the issue, but it introduces more complex and
thp-specific handling in migration code, so it might not good.

So this patch is suggesting to fix the issue by enabling thp migration for
shmem thp.  Both of anon/shmem thp are migratable so we don't need
precheck about the type of thps.

Link: http://lkml.kernel.org/r/20180406030706.GA2434@hori1.linux.bs1.fc.nec.co.jp
Fixes: commit 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early")
Signed-off-by: Naoya Horiguchi 
Acked-by: Kirill A. Shutemov 
Cc: Zi Yan 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'mm-rst' into docs-next

2018-04-16T20:25:08+00:00

Mike Rapoport says:

  These patches convert files in Documentation/vm to ReST format, add an
  initial index and link it to the top level documentation.

  There are no contents changes in the documentation, except few spelling
  fixes. The relatively large diffstat stems from the indentation and
  paragraph wrapping changes.

  I've tried to keep the formatting as consistent as possible, but I could
  miss some places that needed markup and add some markup where it was not
  necessary.

[jc: significant conflicts in vm/hmm.rst]

docs/vm: rename documentation files to .rst

2018-04-16T20:18:15+00:00

Signed-off-by: Mike Rapoport 
Signed-off-by: Jonathan Corbet

page cache: use xa_lock

2018-04-11T17:28:39+00:00

Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root.  Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.

[willy@infradead.org: fix nds32, fs/dax.c]
  Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Jeff Layton 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Ryusuke Konishi 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: kernel-doc: add missing parameter descriptions

2018-04-06T04:36:27+00:00

Link: http://lkml.kernel.org/r/1519585191-10180-4-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport 
Reviewed-by: Andrew Morton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, swap: Add infrastructure for saving page metadata on swap

2018-03-18T14:38:45+00:00

If a processor supports special metadata for a page, for example ADI
version tags on SPARC M7, this metadata must be saved when the page is
swapped out. The same metadata must be restored when the page is swapped
back in. This patch adds two new architecture specific functions -
arch_do_swap_page() to be called when a page is swapped in, and
arch_unmap_one() to be called when a page is being unmapped for swap
out. These architecture hooks allow page metadata to be saved if the
architecture supports it.

Signed-off-by: Khalid Aziz 
Cc: Khalid Aziz 
Acked-by: Jerome Marchand 
Reviewed-by: Anthony Yznaga 
Acked-by: Andrew Morton 
Signed-off-by: David S. Miller

mm: remove cold parameter from free_hot_cold_page*

2017-11-16T02:21:06+00:00

Most callers users of free_hot_cold_page claim the pages being released
are cache hot.  The exception is the page reclaim paths where it is
likely that enough pages will be freed in the near future that the
per-cpu lists are going to be recycled and the cache hotness information
is lost.  As no one really cares about the hotness of pages being
released to the allocator, just ditch the parameter.

The APIs are renamed to indicate that it's no longer about hot/cold
pages.  It should also be less confusing as there are subtle differences
between them.  __free_pages drops a reference and frees a page when the
refcount reaches zero.  free_hot_cold_page handled pages whose refcount
was already zero which is non-obvious from the name.  free_unref_page
should be more obvious.

No performance impact is expected as the overhead is marginal.  The
parameter is removed simply because it is a bit stupid to have a useless
parameter copied everywhere.

[mgorman@techsingularity.net: add pages to head, not tail]
  Link: http://lkml.kernel.org/r/20171019154321.qtpzaeftoyyw4iey@techsingularity.net
Link: http://lkml.kernel.org/r/20171018075952.10627-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Andi Kleen 
Cc: Dave Chinner 
Cc: Dave Hansen 
Cc: Jan Kara 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/rmap.c: remove redundant variable cend

2017-11-16T02:21:04+00:00

Variable cend is set but never read, hence it is redundant and can be
removed.

Cleans up clang build warning: Value stored to 'cend' is never read

Link: http://lkml.kernel.org/r/20171011174942.1372-1-colin.king@canonical.com
Fixes: 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2")
Signed-off-by: Colin Ian King 
Acked-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds