linux-stable.git/Documentation/admin-guide/mm, branch linux-5.15.y

proc: fix documentation and description of pagemap

2022-03-08T18:12:54+00:00

commit dd21bfa425c098b95ca86845f8e7d1ec1ddf6e4a upstream.

Since bit 57 was exported for uffd-wp write-protected (commit
fb8e37f35a2f: "mm/pagemap: export uffd-wp protection information"),
fixing it can reduce some unnecessary confusion.

Link: https://lkml.kernel.org/r/20220301044538.3042713-1-yun.zhou@windriver.com
Fixes: fb8e37f35a2fe1 ("mm/pagemap: export uffd-wp protection information")
Signed-off-by: Yun Zhou 
Reviewed-by: Peter Xu 
Cc: Jonathan Corbet 
Cc: Tiberiu A Georgescu 
Cc: Florian Schmidt 
Cc: Ivan Teterevkov 
Cc: SeongJae Park 
Cc: Yang Shi 
Cc: David Hildenbrand 
Cc: Axel Rasmussen 
Cc: Miaohe Lin 
Cc: Andrea Arcangeli 
Cc: Colin Cross 
Cc: Alistair Popple 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'akpm' (patches from Andrew)

2021-09-08T19:55:35+00:00

Merge more updates from Andrew Morton:
 "147 patches, based on 7d2a07b769330c34b4deabeed939325c77a7ec2f.

  Subsystems affected by this patch series: mm (memory-hotplug, rmap,
  ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
  alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
  checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
  selftests, ipc, and scripts"

* emailed patches from Andrew Morton : (94 commits)
  scripts: check_extable: fix typo in user error message
  mm/workingset: correct kernel-doc notations
  ipc: replace costly bailout check in sysvipc_find_ipc()
  selftests/memfd: remove unused variable
  Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
  configs: remove the obsolete CONFIG_INPUT_POLLDEV
  prctl: allow to setup brk for et_dyn executables
  pid: cleanup the stale comment mentioning pidmap_init().
  kernel/fork.c: unexport get_{mm,task}_exe_file
  coredump: fix memleak in dump_vma_snapshot()
  fs/coredump.c: log if a core dump is aborted due to changed file permissions
  nilfs2: use refcount_dec_and_lock() to fix potential UAF
  nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
  nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
  nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
  nilfs2: fix NULL pointer in nilfs_##name##_attr_release
  nilfs2: fix memory leak in nilfs_sysfs_create_device_group
  trap: cleanup trap_init()
  init: move usermodehelper_enable() to populate_rootfs()
  ...

Documentation: add documents for DAMON

2021-09-08T18:50:25+00:00

This commit adds documents for DAMON under
`Documentation/admin-guide/mm/damon/` and `Documentation/vm/damon/`.

Link: https://lkml.kernel.org/r/20210716081449.22187-11-sj38.park@gmail.com
Signed-off-by: SeongJae Park 
Reviewed-by: Fernand Sieber 
Reviewed-by: Markus Boehme 
Cc: Alexander Shishkin 
Cc: Amit Shah 
Cc: Benjamin Herrenschmidt 
Cc: Brendan Higgins 
Cc: David Hildenbrand 
Cc: David Rientjes 
Cc: David Woodhouse 
Cc: Fan Du 
Cc: Greg Kroah-Hartman 
Cc: Greg Thelen 
Cc: Ingo Molnar 
Cc: Joe Perches 
Cc: Jonathan Cameron 
Cc: Jonathan Corbet 
Cc: Leonard Foerster 
Cc: Marco Elver 
Cc: Maximilian Heyne 
Cc: Mel Gorman 
Cc: Minchan Kim 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Shakeel Butt 
Cc: Shuah Khan 
Cc: Steven Rostedt (VMware) 
Cc: Vladimir Davydov 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory-hotplug.rst: complete admin-guide overhaul

2021-09-08T18:50:22+00:00

The memory hot(un)plug documentation is outdated and incomplete.  Most of
the content dates back to 2007, so it's time for a major overhaul.

Let's rewrite, reorganize and update most parts of the documentation.  In
addition to memory hot(un)plug, also add some details regarding
ZONE_MOVABLE, with memory hotunplug being one of its main consumers.

Drop the file history, that information can more reliably be had from the
git log.

The style of the document is also properly fixed that e.g., "restview"
renders it cleanly now.

In the future, we might add some more details about virt users like
virtio-mem, the XEN balloon, the Hyper-V balloon and ppc64 dlpar.

Link: https://lkml.kernel.org/r/20210707073205.3835-3-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Michal Hocko 
Reviewed-by: Mike Rapoport 
Reviewed-by: Oscar Salvador 
Cc: Mike Kravetz 
Cc: Dave Hansen 
Cc: Matthew Wilcox 
Cc: Anshuman Khandual 
Cc: Muchun Song 
Cc: Pavel Tatashin 
Cc: Jonathan Corbet 
Cc: Stephen Rothwell 

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory-hotplug.rst: remove locking details from admin-guide

2021-09-08T18:50:22+00:00

Patch series "memory-hotplug.rst: complete admin-guide overhaul", v3.

This patch (of 2):

We have the same content at Documentation/core-api/memory-hotplug.rst and
it doesn't fit into the admin-guide.  The documentation was accidentially
duplicated when merging.

Link: https://lkml.kernel.org/r/20210707073205.3835-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210707073205.3835-2-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Mike Rapoport 
Acked-by: Michal Hocko 
Reviewed-by: Oscar Salvador 
Cc: Mike Kravetz 
Cc: Dave Hansen 
Cc: Matthew Wilcox 
Cc: Anshuman Khandual 
Cc: Muchun Song 
Cc: Pavel Tatashin 
Cc: Jonathan Corbet 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/mempolicy: advertise new MPOL_PREFERRED_MANY

2021-09-03T16:58:17+00:00

Adds a new mode to the existing mempolicy modes, MPOL_PREFERRED_MANY.

MPOL_PREFERRED_MANY will be adequately documented in the internal
admin-guide with this patch.  Eventually, the man pages for mbind(2),
get_mempolicy(2), set_mempolicy(2) and numactl(8) will also have text
about this mode.  Those shall contain the canonical reference.

NUMA systems continue to become more prevalent.  New technologies like
PMEM make finer grain control over memory access patterns increasingly
desirable.  MPOL_PREFERRED_MANY allows userspace to specify a set of nodes
that will be tried first when performing allocations.  If those
allocations fail, all remaining nodes will be tried.  It's a straight
forward API which solves many of the presumptive needs of system
administrators wanting to optimize workloads on such machines.  The mode
will work either per VMA, or per thread.

[Michal Hocko: refine kernel doc for MPOL_PREFERRED_MANY]

Link: https://lore.kernel.org/r/20200630212517.308045-13-ben.widawsky@intel.com
Link: https://lkml.kernel.org/r/1627970362-61305-5-git-send-email-feng.tang@intel.com
Signed-off-by: Ben Widawsky 
Signed-off-by: Feng Tang 
Acked-by: Michal Hocko 
Cc: Andi Kleen 
Cc: Andrea Arcangeli 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Huang Ying 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Mike Kravetz 
Cc: Randy Dunlap 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

userfaultfd/shmem: advertise shmem minor fault support

2021-07-01T03:47:27+00:00

Now that the feature is fully implemented (the faulting path hooks exist
so userspace is notified, and the ioctl to resolve such faults is
available), advertise this as a supported feature.

Link: https://lkml.kernel.org/r/20210503180737.2487560-6-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: Hugh Dickins 
Acked-by: Peter Xu 
Cc: Alexander Viro 
Cc: Andrea Arcangeli 
Cc: Brian Geffon 
Cc: "Dr . David Alan Gilbert" 
Cc: Jerome Glisse 
Cc: Joe Perches 
Cc: Kirill A. Shutemov 
Cc: Lokesh Gidra 
Cc: Mike Kravetz 
Cc: Mike Rapoport 
Cc: Mina Almasry 
Cc: Oliver Upton 
Cc: Shaohua Li 
Cc: Shuah Khan 
Cc: Stephen Rothwell 
Cc: Wang Qing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/pagemap: export uffd-wp protection information

2021-07-01T03:47:27+00:00

Export the PTE/PMD status of uffd-wp to pagemap too.

Link: https://lkml.kernel.org/r/20210428225030.9708-6-peterx@redhat.com
Signed-off-by: Peter Xu 
Cc: Alexander Viro 
Cc: Andrea Arcangeli 
Cc: Axel Rasmussen 
Cc: Brian Geffon 
Cc: "Dr . David Alan Gilbert" 
Cc: Hugh Dickins 
Cc: Jerome Glisse 
Cc: Joe Perches 
Cc: Kirill A. Shutemov 
Cc: Lokesh Gidra 
Cc: Mike Kravetz 
Cc: Mike Rapoport 
Cc: Mina Almasry 
Cc: Oliver Upton 
Cc: Shaohua Li 
Cc: Shuah Khan 
Cc: Stephen Rothwell 
Cc: Wang Qing 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap

2021-07-01T03:47:25+00:00

Add a kernel parameter hugetlb_free_vmemmap to enable the feature of
freeing unused vmemmap pages associated with each hugetlb page on boot.

We disable PMD mapping of vmemmap pages for x86-64 arch when this feature
is enabled.  Because vmemmap_remap_free() depends on vmemmap being base
page mapped.

Link: https://lkml.kernel.org/r/20210510030027.56044-8-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Reviewed-by: Oscar Salvador 
Reviewed-by: Barry Song 
Reviewed-by: Miaohe Lin 
Tested-by: Chen Huang 
Tested-by: Bodeddula Balasubramaniam 
Reviewed-by: Mike Kravetz 
Cc: Alexander Viro 
Cc: Andy Lutomirski 
Cc: Anshuman Khandual 
Cc: Balbir Singh 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: David Rientjes 
Cc: HORIGUCHI NAOYA 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Joao Martins 
Cc: Joerg Roedel 
Cc: Jonathan Corbet 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: Mina Almasry 
Cc: Oliver Neukum 
Cc: Paul E. McKenney 
Cc: Pawan Gupta 
Cc: Peter Zijlstra 
Cc: Randy Dunlap 
Cc: Thomas Gleixner 
Cc: Xiongchun Duan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page

2021-07-01T03:47:25+00:00

When we free a HugeTLB page to the buddy allocator, we need to allocate
the vmemmap pages associated with it.  However, we may not be able to
allocate the vmemmap pages when the system is under memory pressure.  In
this case, we just refuse to free the HugeTLB page.  This changes behavior
in some corner cases as listed below:

 1) Failing to free a huge page triggered by the user (decrease nr_pages).

    User needs to try again later.

 2) Failing to free a surplus huge page when freed by the application.

    Try again later when freeing a huge page next time.

 3) Failing to dissolve a free huge page on ZONE_MOVABLE via
    offline_pages().

    This can happen when we have plenty of ZONE_MOVABLE memory, but
    not enough kernel memory to allocate vmemmmap pages.  We may even
    be able to migrate huge page contents, but will not be able to
    dissolve the source huge page.  This will prevent an offline
    operation and is unfortunate as memory offlining is expected to
    succeed on movable zones.  Users that depend on memory hotplug
    to succeed for movable zones should carefully consider whether the
    memory savings gained from this feature are worth the risk of
    possibly not being able to offline memory in certain situations.

 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via
    alloc_contig_range() - once we have that handling in place. Mainly
    affects CMA and virtio-mem.

    Similar to 3). virito-mem will handle migration errors gracefully.
    CMA might be able to fallback on other free areas within the CMA
    region.

Vmemmap pages are allocated from the page freeing context.  In order for
those allocations to be not disruptive (e.g.  trigger oom killer)
__GFP_NORETRY is used.  hugetlb_lock is dropped for the allocation because
a non sleeping allocation would be too fragile and it could fail too
easily under memory pressure.  GFP_ATOMIC or other modes to access memory
reserves is not used because we want to prevent consuming reserves under
heavy hugetlb freeing.

[mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page]
  Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com
[willy@infradead.org: fix alloc_vmemmap_page_list documentation warning]
  Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org

Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Signed-off-by: Mike Kravetz 
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Mike Kravetz 
Reviewed-by: Oscar Salvador 
Cc: Alexander Viro 
Cc: Andy Lutomirski 
Cc: Anshuman Khandual 
Cc: Balbir Singh 
Cc: Barry Song 
Cc: Bodeddula Balasubramaniam 
Cc: Borislav Petkov 
Cc: Chen Huang 
Cc: Dave Hansen 
Cc: David Hildenbrand 
Cc: David Rientjes 
Cc: HORIGUCHI NAOYA 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Joao Martins 
Cc: Joerg Roedel 
Cc: Jonathan Corbet 
Cc: Matthew Wilcox 
Cc: Miaohe Lin 
Cc: Michal Hocko 
Cc: Mina Almasry 
Cc: Oliver Neukum 
Cc: Paul E. McKenney 
Cc: Pawan Gupta 
Cc: Peter Zijlstra 
Cc: Randy Dunlap 
Cc: Thomas Gleixner 
Cc: Xiongchun Duan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds