linux.git/mm/page_alloc.c, branch v5.4-rc2 Linux kernel source tree Merge branch 'hugepage-fallbacks' (hugepatch patches from David Rientjes) 2019-09-28T21:26:47+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-09-28T21:26:47+00:00 edf445ad7c8d58c2784a5b733790e80999093d8f Merge hugepage allocation updates from David Rientjes: "We (mostly Linus, Andrea, and myself) have been discussing offlist how to implement a sane default allocation strategy for hugepages on NUMA platforms. With these reverts in place, the page allocator will happily allocate a remote hugepage immediately rather than try to make a local hugepage available. This incurs a substantial performance degradation when memory compaction would have otherwise made a local hugepage available. This series reverts those reverts and attempts to propose a more sane default allocation strategy specifically for hugepages. Andrea acknowledges this is likely to fix the swap storms that he originally reported that resulted in the patches that removed __GFP_THISNODE from hugepage allocations. The immediate goal is to return 5.3 to the behavior the kernel has implemented over the past several years so that remote hugepages are not immediately allocated when local hugepages could have been made available because the increased access latency is untenable. The next goal is to introduce a sane default allocation strategy for hugepages allocations in general regardless of the configuration of the system so that we prevent thrashing of local memory when compaction is unlikely to succeed and can prefer remote hugepages over remote native pages when the local node is low on memory." Note on timing: this reverts the hugepage VM behavior changes that got introduced fairly late in the 5.3 cycle, and that fixed a huge performance regression for certain loads that had been around since 4.18. Andrea had this note: "The regression of 4.18 was that it was taking hours to start a VM where 3.10 was only taking a few seconds, I reported all the details on lkml when it was finally tracked down in August 2018. https://lore.kernel.org/linux-mm/20180820032640.9896-2-aarcange@redhat.com/ __GFP_THISNODE in MADV_HUGEPAGE made the above enterprise vfio workload degrade like in the "current upstream" above. And it still would have been that bad as above until 5.3-rc5" where the bad behavior ends up happening as you fill up a local node, and without that change, you'd get into the nasty swap storm behavior due to compaction working overtime to make room for more memory on the nodes. As a result 5.3 got the two performance fix reverts in rc5. However, David Rientjes then noted that those performance fixes in turn regressed performance for other loads - although not quite to the same degree. He suggested reverting the reverts and instead replacing them with two small changes to how hugepage allocations are done (patch descriptions rephrased by me): - "avoid expensive reclaim when compaction may not succeed": just admit that the allocation failed when you're trying to allocate a huge-page and compaction wasn't successful. - "allow hugepage fallback to remote nodes when madvised": when that node-local huge-page allocation failed, retry without forcing the local node. but by then I judged it too late to replace the fixes for a 5.3 release. So 5.3 was released with behavior that harked back to the pre-4.18 logic. But now we're in the merge window for 5.4, and we can see if this alternate model fixes not just the horrendous swap storm behavior, but also restores the performance regression that the late reverts caused. Fingers crossed. * emailed patches from David Rientjes <rientjes@google.com>: mm, page_alloc: allow hugepage fallback to remote nodes when madvised mm, page_alloc: avoid expensive reclaim when compaction may not succeed Revert "Revert "Revert "mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask"" Revert "Revert "mm, thp: restore node-local hugepage allocations"" 
Merge hugepage allocation updates from David Rientjes:
 "We (mostly Linus, Andrea, and myself) have been discussing offlist how
  to implement a sane default allocation strategy for hugepages on NUMA
  platforms.

  With these reverts in place, the page allocator will happily allocate
  a remote hugepage immediately rather than try to make a local hugepage
  available. This incurs a substantial performance degradation when
  memory compaction would have otherwise made a local hugepage
  available.

  This series reverts those reverts and attempts to propose a more sane
  default allocation strategy specifically for hugepages. Andrea
  acknowledges this is likely to fix the swap storms that he originally
  reported that resulted in the patches that removed __GFP_THISNODE from
  hugepage allocations.

  The immediate goal is to return 5.3 to the behavior the kernel has
  implemented over the past several years so that remote hugepages are
  not immediately allocated when local hugepages could have been made
  available because the increased access latency is untenable.

  The next goal is to introduce a sane default allocation strategy for
  hugepages allocations in general regardless of the configuration of
  the system so that we prevent thrashing of local memory when
  compaction is unlikely to succeed and can prefer remote hugepages over
  remote native pages when the local node is low on memory."

Note on timing: this reverts the hugepage VM behavior changes that got
introduced fairly late in the 5.3 cycle, and that fixed a huge
performance regression for certain loads that had been around since
4.18.

Andrea had this note:

 "The regression of 4.18 was that it was taking hours to start a VM
  where 3.10 was only taking a few seconds, I reported all the details
  on lkml when it was finally tracked down in August 2018.

     https://lore.kernel.org/linux-mm/20180820032640.9896-2-aarcange@redhat.com/

  __GFP_THISNODE in MADV_HUGEPAGE made the above enterprise vfio
  workload degrade like in the "current upstream" above. And it still
  would have been that bad as above until 5.3-rc5"

where the bad behavior ends up happening as you fill up a local node,
and without that change, you'd get into the nasty swap storm behavior
due to compaction working overtime to make room for more memory on the
nodes.

As a result 5.3 got the two performance fix reverts in rc5.

However, David Rientjes then noted that those performance fixes in turn
regressed performance for other loads - although not quite to the same
degree.  He suggested reverting the reverts and instead replacing them
with two small changes to how hugepage allocations are done (patch
descriptions rephrased by me):

 - "avoid expensive reclaim when compaction may not succeed": just admit
   that the allocation failed when you're trying to allocate a huge-page
   and compaction wasn't successful.

 - "allow hugepage fallback to remote nodes when madvised": when that
   node-local huge-page allocation failed, retry without forcing the
   local node.

but by then I judged it too late to replace the fixes for a 5.3 release.
So 5.3 was released with behavior that harked back to the pre-4.18 logic.

But now we're in the merge window for 5.4, and we can see if this
alternate model fixes not just the horrendous swap storm behavior, but
also restores the performance regression that the late reverts caused.

Fingers crossed.

* emailed patches from David Rientjes <rientjes@google.com>:
  mm, page_alloc: allow hugepage fallback to remote nodes when madvised
  mm, page_alloc: avoid expensive reclaim when compaction may not succeed
  Revert "Revert "Revert "mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask""
  Revert "Revert "mm, thp: restore node-local hugepage allocations""
mm, page_alloc: avoid expensive reclaim when compaction may not succeed 2019-09-28T21:05:38+00:00 David Rientjes rientjes@google.com 2019-09-04T19:54:22+00:00 b39d0ee2632d2f4fb180e8e4eba33736283f23de Memory compaction has a couple significant drawbacks as the allocation order increases, specifically: - isolate_freepages() is responsible for finding free pages to use as migration targets and is implemented as a linear scan of memory starting at the end of a zone, - failing order-0 watermark checks in memory compaction does not account for how far below the watermarks the zone actually is: to enable migration, there must be *some* free memory available. Per the above, watermarks are not always suffficient if isolate_freepages() cannot find the free memory but it could require hundreds of MBs of reclaim to even reach this threshold (read: potentially very expensive reclaim with no indication compaction can be successful), and - if compaction at this order has failed recently so that it does not even run as a result of deferred compaction, looping through reclaim can often be pointless. For hugepage allocations, these are quite substantial drawbacks because these are very high order allocations (order-9 on x86) and falling back to doing reclaim can potentially be *very* expensive without any indication that compaction would even be successful. Reclaim itself is unlikely to free entire pageblocks and certainly no reliance should be put on it to do so in isolation (recall lumpy reclaim). This means we should avoid reclaim and simply fail hugepage allocation if compaction is deferred. It is also not helpful to thrash a zone by doing excessive reclaim if compaction may not be able to access that memory. If order-0 watermarks fail and the allocation order is sufficiently large, it is likely better to fail the allocation rather than thrashing the zone. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Stefan Priebe - Profihost AG <s.priebe@profihost.ag> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Memory compaction has a couple significant drawbacks as the allocation
order increases, specifically:

 - isolate_freepages() is responsible for finding free pages to use as
   migration targets and is implemented as a linear scan of memory
   starting at the end of a zone,

 - failing order-0 watermark checks in memory compaction does not account
   for how far below the watermarks the zone actually is: to enable
   migration, there must be *some* free memory available.  Per the above,
   watermarks are not always suffficient if isolate_freepages() cannot
   find the free memory but it could require hundreds of MBs of reclaim to
   even reach this threshold (read: potentially very expensive reclaim with
   no indication compaction can be successful), and

 - if compaction at this order has failed recently so that it does not even
   run as a result of deferred compaction, looping through reclaim can often
   be pointless.

For hugepage allocations, these are quite substantial drawbacks because
these are very high order allocations (order-9 on x86) and falling back to
doing reclaim can potentially be *very* expensive without any indication
that compaction would even be successful.

Reclaim itself is unlikely to free entire pageblocks and certainly no
reliance should be put on it to do so in isolation (recall lumpy reclaim).
This means we should avoid reclaim and simply fail hugepage allocation if
compaction is deferred.

It is also not helpful to thrash a zone by doing excessive reclaim if
compaction may not be able to access that memory.  If order-0 watermarks
fail and the allocation order is sufficiently large, it is likely better
to fail the allocation rather than thrashing the zone.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: move mem_cgroup_uncharge out of __page_cache_release() 2019-09-24T22:54:11+00:00 Yang Shi yang.shi@linux.alibaba.com 2019-09-23T22:38:09+00:00 7ae88534cdd96235cd775c03b32a75009355740b A later patch makes THP deferred split shrinker memcg aware, but it needs page->mem_cgroup information in THP destructor, which is called after mem_cgroup_uncharge() now. So move mem_cgroup_uncharge() from __page_cache_release() to compound page destructor, which is called by both THP and other compound pages except HugeTLB. And call it in __put_single_page() for single order page. Link: http://lkml.kernel.org/r/1565144277-36240-3-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
A later patch makes THP deferred split shrinker memcg aware, but it needs
page->mem_cgroup information in THP destructor, which is called after
mem_cgroup_uncharge() now.

So move mem_cgroup_uncharge() from __page_cache_release() to compound page
destructor, which is called by both THP and other compound pages except
HugeTLB.  And call it in __put_single_page() for single order page.

Link: http://lkml.kernel.org/r/1565144277-36240-3-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: thp: extract split_queue_* into a struct 2019-09-24T22:54:11+00:00 Yang Shi yang.shi@linux.alibaba.com 2019-09-23T22:38:06+00:00 364c1eebe453f06f0c1e837eb155a5725c9cd272 Patch series "Make deferred split shrinker memcg aware", v6. Currently THP deferred split shrinker is not memcg aware, this may cause premature OOM with some configuration. For example the below test would run into premature OOM easily: $ cgcreate -g memory:thp $ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes $ cgexec -g memory:thp transhuge-stress 4000 transhuge-stress comes from kernel selftest. It is easy to hit OOM, but there are still a lot THP on the deferred split queue, memcg direct reclaim can't touch them since the deferred split shrinker is not memcg aware. Convert deferred split shrinker memcg aware by introducing per memcg deferred split queue. The THP should be on either per node or per memcg deferred split queue if it belongs to a memcg. When the page is immigrated to the other memcg, it will be immigrated to the target memcg's deferred split queue too. Reuse the second tail page's deferred_list for per memcg list since the same THP can't be on multiple deferred split queues. Make deferred split shrinker not depend on memcg kmem since it is not slab. It doesn't make sense to not shrink THP even though memcg kmem is disabled. With the above change the test demonstrated above doesn't trigger OOM even though with cgroup.memory=nokmem. This patch (of 4): Put split_queue, split_queue_lock and split_queue_len into a struct in order to reduce code duplication when we convert deferred_split to memcg aware in the later patches. Link: http://lkml.kernel.org/r/1565144277-36240-2-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Patch series "Make deferred split shrinker memcg aware", v6.

Currently THP deferred split shrinker is not memcg aware, this may cause
premature OOM with some configuration.  For example the below test would
run into premature OOM easily:

$ cgcreate -g memory:thp
$ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes
$ cgexec -g memory:thp transhuge-stress 4000

transhuge-stress comes from kernel selftest.

It is easy to hit OOM, but there are still a lot THP on the deferred split
queue, memcg direct reclaim can't touch them since the deferred split
shrinker is not memcg aware.

Convert deferred split shrinker memcg aware by introducing per memcg
deferred split queue.  The THP should be on either per node or per memcg
deferred split queue if it belongs to a memcg.  When the page is
immigrated to the other memcg, it will be immigrated to the target memcg's
deferred split queue too.

Reuse the second tail page's deferred_list for per memcg list since the
same THP can't be on multiple deferred split queues.

Make deferred split shrinker not depend on memcg kmem since it is not
slab.  It doesn't make sense to not shrink THP even though memcg kmem is
disabled.

With the above change the test demonstrated above doesn't trigger OOM even
though with cgroup.memory=nokmem.

This patch (of 4):

Put split_queue, split_queue_lock and split_queue_len into a struct in
order to reduce code duplication when we convert deferred_split to memcg
aware in the later patches.

Link: http://lkml.kernel.org/r/1565144277-36240-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm, compaction: raise compaction priority after it withdrawns 2019-09-24T22:54:10+00:00 Vlastimil Babka vbabka@suse.cz 2019-09-23T22:37:32+00:00 494330855641269c8a49f1580f0d4e2ead693245 Mike Kravetz reports that "hugetlb allocations could stall for minutes or hours when should_compact_retry() would return true more often then it should. Specifically, this was in the case where compact_result was COMPACT_DEFERRED and COMPACT_PARTIAL_SKIPPED and no progress was being made." The problem is that the compaction_withdrawn() test in should_compact_retry() includes compaction outcomes that are only possible on low compaction priority, and results in a retry without increasing the priority. This may result in furter reclaim, and more incomplete compaction attempts. With this patch, compaction priority is raised when possible, or should_compact_retry() returns false. The COMPACT_SKIPPED result doesn't really fit together with the other outcomes in compaction_withdrawn(), as that's a result caused by insufficient order-0 pages, not due to low compaction priority. With this patch, it is moved to a new compaction_needs_reclaim() function, and for that outcome we keep the current logic of retrying if it looks like reclaim will be able to help. Link: http://lkml.kernel.org/r/20190806014744.15446-4-mike.kravetz@oracle.com Reported-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Mike Kravetz reports that "hugetlb allocations could stall for minutes or
hours when should_compact_retry() would return true more often then it
should.  Specifically, this was in the case where compact_result was
COMPACT_DEFERRED and COMPACT_PARTIAL_SKIPPED and no progress was being
made."

The problem is that the compaction_withdrawn() test in
should_compact_retry() includes compaction outcomes that are only possible
on low compaction priority, and results in a retry without increasing the
priority.  This may result in furter reclaim, and more incomplete
compaction attempts.

With this patch, compaction priority is raised when possible, or
should_compact_retry() returns false.

The COMPACT_SKIPPED result doesn't really fit together with the other
outcomes in compaction_withdrawn(), as that's a result caused by
insufficient order-0 pages, not due to low compaction priority.  With this
patch, it is moved to a new compaction_needs_reclaim() function, and for
that outcome we keep the current logic of retrying if it looks like
reclaim will be able to help.

Link: http://lkml.kernel.org/r/20190806014744.15446-4-mike.kravetz@oracle.com
Reported-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Tested-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: introduce compound_nr() 2019-09-24T22:54:08+00:00 Matthew Wilcox (Oracle) willy@infradead.org 2019-09-23T22:34:30+00:00 d8c6546b1aea843fbeb4d54a1202f1adda6504be Replace 1 << compound_order(page) with compound_nr(page). Minor improvements in readability. Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Replace 1 << compound_order(page) with compound_nr(page).  Minor
improvements in readability.

Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma 2019-09-21T17:07:42+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-09-21T17:07:42+00:00 84da111de0b4be15bd500deff773f5116f39f7be Pull hmm updates from Jason Gunthorpe: "This is more cleanup and consolidation of the hmm APIs and the very strongly related mmu_notifier interfaces. Many places across the tree using these interfaces are touched in the process. Beyond that a cleanup to the page walker API and a few memremap related changes round out the series: - General improvement of hmm_range_fault() and related APIs, more documentation, bug fixes from testing, API simplification & consolidation, and unused API removal - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE, and make them internal kconfig selects - Hoist a lot of code related to mmu notifier attachment out of drivers by using a refcount get/put attachment idiom and remove the convoluted mmu_notifier_unregister_no_release() and related APIs. - General API improvement for the migrate_vma API and revision of its only user in nouveau - Annotate mmu_notifiers with lockdep and sleeping region debugging Two series unrelated to HMM or mmu_notifiers came along due to dependencies: - Allow pagemap's memremap_pages family of APIs to work without providing a struct device - Make walk_page_range() and related use a constant structure for function pointers" * tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (75 commits) libnvdimm: Enable unit test infrastructure compile checks mm, notifier: Catch sleeping/blocking for !blockable kernel.h: Add non_block_start/end() drm/radeon: guard against calling an unpaired radeon_mn_unregister() csky: add missing brackets in a macro for tlb.h pagewalk: use lockdep_assert_held for locking validation pagewalk: separate function pointers from iterator data mm: split out a new pagewalk.h header from mm.h mm/mmu_notifiers: annotate with might_sleep() mm/mmu_notifiers: prime lockdep mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end mm/mmu_notifiers: remove the __mmu_notifier_invalidate_range_start/end exports mm/hmm: hmm_range_fault() infinite loop mm/hmm: hmm_range_fault() NULL pointer bug mm/hmm: fix hmm_range_fault()'s handling of swapped out pages mm/mmu_notifiers: remove unregister_no_release RDMA/odp: remove ib_ucontext from ib_umem RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm' RDMA/mlx5: Use odp instead of mr->umem in pagefault_mr RDMA/mlx5: Use ib_umem_start instead of umem.address ... 
Pull hmm updates from Jason Gunthorpe:
 "This is more cleanup and consolidation of the hmm APIs and the very
  strongly related mmu_notifier interfaces. Many places across the tree
  using these interfaces are touched in the process. Beyond that a
  cleanup to the page walker API and a few memremap related changes
  round out the series:

   - General improvement of hmm_range_fault() and related APIs, more
     documentation, bug fixes from testing, API simplification &
     consolidation, and unused API removal

   - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE,
     and make them internal kconfig selects

   - Hoist a lot of code related to mmu notifier attachment out of
     drivers by using a refcount get/put attachment idiom and remove the
     convoluted mmu_notifier_unregister_no_release() and related APIs.

   - General API improvement for the migrate_vma API and revision of its
     only user in nouveau

   - Annotate mmu_notifiers with lockdep and sleeping region debugging

  Two series unrelated to HMM or mmu_notifiers came along due to
  dependencies:

   - Allow pagemap's memremap_pages family of APIs to work without
     providing a struct device

   - Make walk_page_range() and related use a constant structure for
     function pointers"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (75 commits)
  libnvdimm: Enable unit test infrastructure compile checks
  mm, notifier: Catch sleeping/blocking for !blockable
  kernel.h: Add non_block_start/end()
  drm/radeon: guard against calling an unpaired radeon_mn_unregister()
  csky: add missing brackets in a macro for tlb.h
  pagewalk: use lockdep_assert_held for locking validation
  pagewalk: separate function pointers from iterator data
  mm: split out a new pagewalk.h header from mm.h
  mm/mmu_notifiers: annotate with might_sleep()
  mm/mmu_notifiers: prime lockdep
  mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end
  mm/mmu_notifiers: remove the __mmu_notifier_invalidate_range_start/end exports
  mm/hmm: hmm_range_fault() infinite loop
  mm/hmm: hmm_range_fault() NULL pointer bug
  mm/hmm: fix hmm_range_fault()'s handling of swapped out pages
  mm/mmu_notifiers: remove unregister_no_release
  RDMA/odp: remove ib_ucontext from ib_umem
  RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'
  RDMA/mlx5: Use odp instead of mr->umem in pagefault_mr
  RDMA/mlx5: Use ib_umem_start instead of umem.address
  ...
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-17T00:25:49+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-09-17T00:25:49+00:00 7e67a859997aad47727aff9c5a32e160da079ce3 Pull scheduler updates from Ingo Molnar: - MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann, Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers. As perf and the scheduler is getting bigger and more complex, document the status quo of current responsibilities and interests, and spread the review pain^H^H^H^H fun via an increase in the Cc: linecount generated by scripts/get_maintainer.pl. :-) - Add another series of patches that brings the -rt (PREEMPT_RT) tree closer to mainline: split the monolithic CONFIG_PREEMPT dependencies into a new CONFIG_PREEMPTION category that will allow the eventual introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches to go though. - Extend the CPU cgroup controller with uclamp.min and uclamp.max to allow the finer shaping of CPU bandwidth usage. - Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS). - Improve the behavior of high CPU count, high thread count applications running under cpu.cfs_quota_us constraints. - Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present. - Improve CPU isolation housekeeping CPU allocation NUMA locality. - Fix deadline scheduler bandwidth calculations and logic when cpusets rebuilds the topology, or when it gets deadline-throttled while it's being offlined. - Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from setscheduler() system calls without creating global serialization. Add new synchronization between cpuset topology-changing events and the deadline acceptance tests in setscheduler(), which were broken before. - Rework the active_mm state machine to be less confusing and more optimal. - Rework (simplify) the pick_next_task() slowpath. - Improve load-balancing on AMD EPYC systems. - ... and misc cleanups, smaller fixes and improvements - please see the Git log for more details. * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits) sched/psi: Correct overly pessimistic size calculation sched/fair: Speed-up energy-aware wake-ups sched/uclamp: Always use 'enum uclamp_id' for clamp_id values sched/uclamp: Update CPU's refcount on TG's clamp changes sched/uclamp: Use TG's clamps to restrict TASK's clamps sched/uclamp: Propagate system defaults to the root group sched/uclamp: Propagate parent clamps sched/uclamp: Extend CPU's cgroup controller sched/topology: Improve load balancing on AMD EPYC systems arch, ia64: Make NUMA select SMP sched, perf: MAINTAINERS update, add submaintainers and reviewers sched/fair: Use rq_lock/unlock in online_fair_sched_group cpufreq: schedutil: fix equation in comment sched: Rework pick_next_task() slow-path sched: Allow put_prev_task() to drop rq->lock sched/fair: Expose newidle_balance() sched: Add task_struct pointer to sched_class::set_curr_task sched: Rework CPU hotplug task selection sched/{rt,deadline}: Fix set_next_task vs pick_next_task sched: Fix kerneldoc comment for ia64_set_curr_task ... 
Pull scheduler updates from Ingo Molnar:

 - MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and
   Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann,
   Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers.

   As perf and the scheduler is getting bigger and more complex,
   document the status quo of current responsibilities and interests,
   and spread the review pain^H^H^H^H fun via an increase in the Cc:
   linecount generated by scripts/get_maintainer.pl. :-)

 - Add another series of patches that brings the -rt (PREEMPT_RT) tree
   closer to mainline: split the monolithic CONFIG_PREEMPT dependencies
   into a new CONFIG_PREEMPTION category that will allow the eventual
   introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches
   to go though.

 - Extend the CPU cgroup controller with uclamp.min and uclamp.max to
   allow the finer shaping of CPU bandwidth usage.

 - Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS).

 - Improve the behavior of high CPU count, high thread count
   applications running under cpu.cfs_quota_us constraints.

 - Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present.

 - Improve CPU isolation housekeeping CPU allocation NUMA locality.

 - Fix deadline scheduler bandwidth calculations and logic when cpusets
   rebuilds the topology, or when it gets deadline-throttled while it's
   being offlined.

 - Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from
   setscheduler() system calls without creating global serialization.
   Add new synchronization between cpuset topology-changing events and
   the deadline acceptance tests in setscheduler(), which were broken
   before.

 - Rework the active_mm state machine to be less confusing and more
   optimal.

 - Rework (simplify) the pick_next_task() slowpath.

 - Improve load-balancing on AMD EPYC systems.

 - ... and misc cleanups, smaller fixes and improvements - please see
   the Git log for more details.

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
  sched/psi: Correct overly pessimistic size calculation
  sched/fair: Speed-up energy-aware wake-ups
  sched/uclamp: Always use 'enum uclamp_id' for clamp_id values
  sched/uclamp: Update CPU's refcount on TG's clamp changes
  sched/uclamp: Use TG's clamps to restrict TASK's clamps
  sched/uclamp: Propagate system defaults to the root group
  sched/uclamp: Propagate parent clamps
  sched/uclamp: Extend CPU's cgroup controller
  sched/topology: Improve load balancing on AMD EPYC systems
  arch, ia64: Make NUMA select SMP
  sched, perf: MAINTAINERS update, add submaintainers and reviewers
  sched/fair: Use rq_lock/unlock in online_fair_sched_group
  cpufreq: schedutil: fix equation in comment
  sched: Rework pick_next_task() slow-path
  sched: Allow put_prev_task() to drop rq->lock
  sched/fair: Expose newidle_balance()
  sched: Add task_struct pointer to sched_class::set_curr_task
  sched: Rework CPU hotplug task selection
  sched/{rt,deadline}: Fix set_next_task vs pick_next_task
  sched: Fix kerneldoc comment for ia64_set_curr_task
  ...
sched/topology: Improve load balancing on AMD EPYC systems 2019-09-03T07:17:37+00:00 Matt Fleming matt@codeblueprint.co.uk 2019-08-08T19:53:01+00:00 a55c7454a8c887b226a01d7eed088ccb5374d81e SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init() for any sched domains with a NUMA distance greater than 2 hops (RECLAIM_DISTANCE). The idea being that it's expensive to balance across domains that far apart. However, as is rather unfortunately explained in: commit 32e45ff43eaf ("mm: increase RECLAIM_DISTANCE to 30") the value for RECLAIM_DISTANCE is based on node distance tables from 2011-era hardware. Current AMD EPYC machines have the following NUMA node distances: node distances: node 0 1 2 3 4 5 6 7 0: 10 16 16 16 32 32 32 32 1: 16 10 16 16 32 32 32 32 2: 16 16 10 16 32 32 32 32 3: 16 16 16 10 32 32 32 32 4: 32 32 32 32 10 16 16 16 5: 32 32 32 32 16 10 16 16 6: 32 32 32 32 16 16 10 16 7: 32 32 32 32 16 16 16 10 where 2 hops is 32. The result is that the scheduler fails to load balance properly across NUMA nodes on different sockets -- 2 hops apart. For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4 (CPUs 32-39) like so, $ numactl -C 0-7,32-39 ./spinner 16 causes all threads to fork and remain on node 0 until the active balancer kicks in after a few seconds and forcibly moves some threads to node 4. Override node_reclaim_distance for AMD Zen. Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Suravee.Suthikulpanit@amd.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas.Lendacky@amd.com Cc: Tony Luck <tony.luck@intel.com> Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> 
SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init()
for any sched domains with a NUMA distance greater than 2 hops
(RECLAIM_DISTANCE). The idea being that it's expensive to balance
across domains that far apart.

However, as is rather unfortunately explained in:

  commit 32e45ff43eaf ("mm: increase RECLAIM_DISTANCE to 30")

the value for RECLAIM_DISTANCE is based on node distance tables from
2011-era hardware.

Current AMD EPYC machines have the following NUMA node distances:

 node distances:
 node   0   1   2   3   4   5   6   7
   0:  10  16  16  16  32  32  32  32
   1:  16  10  16  16  32  32  32  32
   2:  16  16  10  16  32  32  32  32
   3:  16  16  16  10  32  32  32  32
   4:  32  32  32  32  10  16  16  16
   5:  32  32  32  32  16  10  16  16
   6:  32  32  32  32  16  16  10  16
   7:  32  32  32  32  16  16  16  10

where 2 hops is 32.

The result is that the scheduler fails to load balance properly across
NUMA nodes on different sockets -- 2 hops apart.

For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4
(CPUs 32-39) like so,

  $ numactl -C 0-7,32-39 ./spinner 16

causes all threads to fork and remain on node 0 until the active
balancer kicks in after a few seconds and forcibly moves some threads
to node 4.

Override node_reclaim_distance for AMD Zen.

Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suravee.Suthikulpanit@amd.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas.Lendacky@amd.com
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
mm, page_alloc: move_freepages should not examine struct page of reserved memory 2019-08-25T02:48:42+00:00 David Rientjes rientjes@google.com 2019-08-25T00:54:40+00:00 cd961038381f392b364a7c4a040f4576ca415b1a After commit 907ec5fca3dc ("mm: zero remaining unavailable struct pages"), struct page of reserved memory is zeroed. This causes page->flags to be 0 and fixes issues related to reading /proc/kpageflags, for example, of reserved memory. The VM_BUG_ON() in move_freepages_block(), however, assumes that page_zone() is meaningful even for reserved memory. That assumption is no longer true after the aforementioned commit. There's no reason why move_freepages_block() should be testing the legitimacy of page_zone() for reserved memory; its scope is limited only to pages on the zone's freelist. Note that pfn_valid() can be true for reserved memory: there is a backing struct page. The check for page_to_nid(page) is also buggy but reserved memory normally only appears on node 0 so the zeroing doesn't affect this. Move the debug checks to after verifying PageBuddy is true. This isolates the scope of the checks to only be for buddy pages which are on the zone's freelist which move_freepages_block() is operating on. In this case, an incorrect node or zone is a bug worthy of being warned about (and the examination of struct page is acceptable bcause this memory is not reserved). Why does move_freepages_block() gets called on reserved memory? It's simply math after finding a valid free page from the per-zone free area to use as fallback. We find the beginning and end of the pageblock of the valid page and that can bring us into memory that was reserved per the e820. pfn_valid() is still true (it's backed by a struct page), but since it's zero'd we shouldn't make any inferences here about comparing its node or zone. The current node check just happens to succeed most of the time by luck because reserved memory typically appears on node 0. The fix here is to validate that we actually have buddy pages before testing if there's any type of zone or node strangeness going on. We noticed it almost immediately after bringing 907ec5fca3dc in on CONFIG_DEBUG_VM builds. It depends on finding specific free pages in the per-zone free area where the math in move_freepages() will bring the start or end pfn into reserved memory and wanting to claim that entire pageblock as a new migratetype. So the path will be rare, require CONFIG_DEBUG_VM, and require fallback to a different migratetype. Some struct pages were already zeroed from reserve pages before 907ec5fca3c so it theoretically could trigger before this commit. I think it's rare enough under a config option that most people don't run that others may not have noticed. I wouldn't argue against a stable tag and the backport should be easy enough, but probably wouldn't single out a commit that this is fixing. Mel said: : The overhead of the debugging check is higher with this patch although : it'll only affect debug builds and the path is not particularly hot. : If this was a concern, I think it would be reasonable to simply remove : the debugging check as the zone boundaries are checked in : move_freepages_block and we never expect a zone/node to be smaller than : a pageblock and stuck in the middle of another zone. Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1908122036560.10779@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
After commit 907ec5fca3dc ("mm: zero remaining unavailable struct
pages"), struct page of reserved memory is zeroed.  This causes
page->flags to be 0 and fixes issues related to reading
/proc/kpageflags, for example, of reserved memory.

The VM_BUG_ON() in move_freepages_block(), however, assumes that
page_zone() is meaningful even for reserved memory.  That assumption is
no longer true after the aforementioned commit.

There's no reason why move_freepages_block() should be testing the
legitimacy of page_zone() for reserved memory; its scope is limited only
to pages on the zone's freelist.

Note that pfn_valid() can be true for reserved memory: there is a
backing struct page.  The check for page_to_nid(page) is also buggy but
reserved memory normally only appears on node 0 so the zeroing doesn't
affect this.

Move the debug checks to after verifying PageBuddy is true.  This
isolates the scope of the checks to only be for buddy pages which are on
the zone's freelist which move_freepages_block() is operating on.  In
this case, an incorrect node or zone is a bug worthy of being warned
about (and the examination of struct page is acceptable bcause this
memory is not reserved).

Why does move_freepages_block() gets called on reserved memory? It's
simply math after finding a valid free page from the per-zone free area
to use as fallback.  We find the beginning and end of the pageblock of
the valid page and that can bring us into memory that was reserved per
the e820.  pfn_valid() is still true (it's backed by a struct page), but
since it's zero'd we shouldn't make any inferences here about comparing
its node or zone.  The current node check just happens to succeed most
of the time by luck because reserved memory typically appears on node 0.

The fix here is to validate that we actually have buddy pages before
testing if there's any type of zone or node strangeness going on.

We noticed it almost immediately after bringing 907ec5fca3dc in on
CONFIG_DEBUG_VM builds.  It depends on finding specific free pages in
the per-zone free area where the math in move_freepages() will bring the
start or end pfn into reserved memory and wanting to claim that entire
pageblock as a new migratetype.  So the path will be rare, require
CONFIG_DEBUG_VM, and require fallback to a different migratetype.

Some struct pages were already zeroed from reserve pages before
907ec5fca3c so it theoretically could trigger before this commit.  I
think it's rare enough under a config option that most people don't run
that others may not have noticed.  I wouldn't argue against a stable tag
and the backport should be easy enough, but probably wouldn't single out
a commit that this is fixing.

Mel said:

: The overhead of the debugging check is higher with this patch although
: it'll only affect debug builds and the path is not particularly hot.
: If this was a concern, I think it would be reasonable to simply remove
: the debugging check as the zone boundaries are checked in
: move_freepages_block and we never expect a zone/node to be smaller than
: a pageblock and stuck in the middle of another zone.

Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1908122036560.10779@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>