When using a sparse memory model memmap_init_zone() when invoked with
the MEMMAP_EARLY context will skip over pages which aren't valid - ie.
which aren't in a populated region of the sparse memory map.  However if
the memory map is extremely sparse then it can spend a long time
linearly checking each PFN in a large non-populated region of the memory
map & skipping it in turn.

When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient
information to quickly discover the next valid PFN given an invalid one
by searching through the list of memory regions & skipping forwards to
the first PFN covered by the memory region to the right of the
non-populated region.  Implement this in order to speed up
memmap_init_zone() for systems with extremely sparse memory maps.

James said "I have tested this patch on a virtual model of a Samurai CPU
with a sparse memory map.  The kernel boot time drops from 109 to
62 seconds. "

Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@imgtec.comSigned-off-by: NPaul Burton <paul.burton@imgtec.com>
Tested-by: NJames Hartley <james.hartley@imgtec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A "compact_daemon_wake" vmstat exists that represents the number of
times kcompactd has woken up.  This doesn't represent how much work it
actually did, though.

It's useful to understand how much compaction work is being done by
kcompactd versus other methods such as direct compaction and explicitly
triggered per-node (or system) compaction.

This adds two new vmstats: "compact_daemon_migrate_scanned" and
"compact_daemon_free_scanned" to represent the number of pages kcompactd
has scanned as part of its migration scanner and freeing scanner,
respectively.

These values are still accounted for in the general
"compact_migrate_scanned" and "compact_free_scanned" for compatibility.

It could be argued that explicitly triggered compaction could also be
tracked separately, and that could be added if others find it useful.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1612071749390.69852@chino.kir.corp.google.comSigned-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 682a3385 ("mm, page_alloc: inline the fast path of the
zonelist iterator") changed how next_zones_zonelist() is called, by
adding a static inline function to do the fast path.  This function
adds:

       if (likely(!nodes && zonelist_zone_idx(z) <= highest_zoneidx))
               return z;
       return __next_zones_zonelist(z, highest_zoneidx, nodes);

Where __next_zones_zonelist() is only called when nodes is not NULL or
zonelist_zone_idx(z) is less than highest_zoneidx.

The original next_zone_zonelist() was converted to __next_zones_zonelist()
but it still maintained:

	if (likely(nodes == NULL))

Which is now actually a very unlikely, as it is only called with nodes
equal to NULL when zonelist_zone_idx(z) is greater than highest_zoneidx.

Before this commit, this if had this statistic:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
  837895   446078  34 next_zones_zonelist            mmzone.c             63

After this commit, it has:

 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
      10   173840  99 __next_zones_zonelist          mmzone.c             63

Thus, the if statement is now much more unlikely than it ever was as a
likely.

Link: http://lkml.kernel.org/r/20170105200102.77989567@gandalf.local.homeSigned-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix kernel-doc warnings in mm/filemap.c:

  mm/filemap.c:993: warning: No description found for parameter '__page'
  mm/filemap.c:993: warning: Excess function parameter 'page' description in '__lock_page'

Link: http://lkml.kernel.org/r/a66fe492-518c-ad6c-5f03-5e8b721fb451@infradead.orgSigned-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These are no longer used outside mm/filemap.c, so un-export them and
make them static where possible.  These were exported specifically for
NFS use in commit a4796e37 ("MM: export page_wakeup functions").

Link: http://lkml.kernel.org/r/20170103182234.30141-3-npiggin@gmail.comSigned-off-by: NNicholas Piggin <npiggin@gmail.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently we have tracepoints for both active and inactive LRU lists
reclaim but we do not have any which would tell us why we we decided to
age the active list.  Without that it is quite hard to diagnose
active/inactive lists balancing.  Add mm_vmscan_inactive_list_is_low
tracepoint to tell us this information.

Link: http://lkml.kernel.org/r/20170104101942.4860-8-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm_vmscan_lru_shrink_inactive will currently report the number of
scanned and reclaimed pages.  This doesn't give us an idea how the
reclaim went except for the overall effectiveness though.  Export and
show other counters which will tell us why we couldn't reclaim some
pages.

	- nr_dirty, nr_writeback, nr_congested and nr_immediate tells
	  us how many pages are blocked due to IO
	- nr_activate tells us how many pages were moved to the active
	  list
	- nr_ref_keep reports how many pages are kept on the LRU due
	  to references (mostly for the file pages which are about to
	  go for another round through the inactive list)
	- nr_unmap_fail - how many pages failed to unmap

All these are rather low level so they might change in future but the
tracepoint is already implementation specific so no tools should be
depending on its stability.

Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

shrink_page_list returns quite some counters back to its caller.
Extract the existing 5 into struct reclaim_stat because this makes the
code easier to follow and also allows further counters to be returned.

While we are at it, make all of them unsigned rather than unsigned long
as we do not really need full 64b for them (we never scan more than
SWAP_CLUSTER_MAX pages at once).  This should reduce some stack space.

This patch shouldn't introduce any functional change.

Link: http://lkml.kernel.org/r/20170104101942.4860-6-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm_vmscan_lru_isolate currently prints only whether the LRU we isolate
from is file or anonymous but we do not know which LRU this is.

It is useful to know whether the list is active or inactive, since we
are using the same function to isolate pages from both of them and it's
hard to distinguish otherwise.

Link: http://lkml.kernel.org/r/20170104101942.4860-5-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm_vmscan_lru_isolate shows the number of requested, scanned and taken
pages.  This is mostly OK but on 32b systems the number of scanned pages
is quite misleading because it includes both the scanned and skipped
pages.  Moreover the skipped part is scaled based on the number of taken
pages.  Let's report the exact numbers without any additional logic and
add the number of skipped pages.

This should make the reported data much more easier to interpret.

Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Our reclaim process has several tracepoints to tell us more about how
things are progressing.  We are, however, missing a tracepoint to track
active list aging.  Introduce mm_vmscan_lru_shrink_active which reports
the number of

	- nr_taken is number of isolated pages from the active list
	- nr_referenced pages which tells us that we are hitting referenced
	  pages which are deactivated. If this is a large part of the
	  reported nr_deactivated pages then we might be hitting into
	  the active list too early because they might be still part of
	  the working set. This might help to debug performance issues.
	- nr_active pages which tells us how many pages are kept on the
	  active list - mostly exec file backed pages. A high number can
	  indicate that we might be trashing on executables.

[mhocko@suse.com: update]
  Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

pmd_trans_unstable does an atomic read on the pmd so it doesn't require
the pmd_lock for the same check.

This also removes the special assumption that the mmap_sem is hold for
writing if prot_numa is not set.  userfaultfd will hold the mmap_sem
only for reading in change_pte_range like prot_numa, but it will not set
prot_numa.

This is always a valid micro-optimization regardless of userfaultfd.

[kirill@shutemov.name: drop unneeded pmd_trans_unstable(pmd) check after __split_huge_pmd()]
  Link: http://lkml.kernel.org/r/20170208120421.GE5578@node.shutemov.name
Link: http://lkml.kernel.org/r/20161216144821.5183-43-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the atomic copy_user fails because of a real dangling userland
pointer, we won't go back into the shmem method, so when the method
returns it must not leave anything charged up, except the page itself.

Link: http://lkml.kernel.org/r/20161216144821.5183-37-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the non atomic version of __SetPageUptodate while the page is still
private and not visible to lookup operations.  Using the non atomic
version after the page is already visible to lookups is unsafe as there
would be concurrent lock_page operation modifying the page->flags while
it runs.

This solves a lockup in find_lock_entry with the userfaultfd_shmem
selftest.

  userfaultfd_shm D14296   691      1 0x00000004
  Call Trace:
   schedule+0x3d/0x90
   schedule_timeout+0x228/0x420
   io_schedule_timeout+0xa4/0x110
   __lock_page+0x12d/0x170
   find_lock_entry+0xa4/0x190
   shmem_getpage_gfp+0xb9/0xc30
   shmem_fault+0x70/0x1c0
   __do_fault+0x21/0x150
   handle_mm_fault+0xec9/0x1490
   __do_page_fault+0x20d/0x520
   trace_do_page_fault+0x61/0x270
   do_async_page_fault+0x19/0x80
   async_page_fault+0x25/0x30

Link: http://lkml.kernel.org/r/20170116180408.12184-2-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A VM_BUG_ON triggered on the shmem selftest.

Link: http://lkml.kernel.org/r/20161216144821.5183-36-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When userfaultfd hugetlbfs support was originally added, it followed the
pattern of anon mappings and did not support any vmas marked VM_SHARED.
As such, support was only added for private mappings.

Remove this limitation and support shared mappings.  The primary
functional change required is adding pages to the page cache.  More subtle
changes are required for huge page reservation handling in error paths.  A
lengthy comment in the code describes the reservation handling.

[mike.kravetz@oracle.com: update]
  Link: http://lkml.kernel.org/r/c9c8cafe-baa7-05b4-34ea-1dfa5523a85f@oracle.com
Link: http://lkml.kernel.org/r/1487195210-12839-1-git-send-email-mike.kravetz@oracle.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When processing a page fault in shared memory area for not present page,
check the VMA determine if faults are to be handled by userfaultfd.  If
so, delegate the page fault to handle_userfault.

Link: http://lkml.kernel.org/r/20161216144821.5183-33-aarcange@redhat.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The shmem_mcopy_atomic_pte implements low lever part of UFFDIO_COPY
operation for shared memory VMAs.  It's based on mcopy_atomic_pte with
adjustments necessary for shared memory pages.

Link: http://lkml.kernel.org/r/20161216144821.5183-32-aarcange@redhat.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It resolves this build error:

All errors (new ones prefixed by >>):

   mm/shmem.c: In function 'shmem_mcopy_atomic_pte':
   >> mm/shmem.c:2228:2: error: implicit declaration of function 'update_mmu_cache' [-Werror=implicit-function-declaration]
        update_mmu_cache(dst_vma, dst_addr, dst_pte);

microblaze may have to be also updated to define it in asm/pgtable.h
like the other archs, then this header inclusion can be removed.

Link: http://lkml.kernel.org/r/20161216144821.5183-31-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently userfault relies on vma_is_anonymous and vma_is_hugetlb to
ensure compatibility of a VMA with userfault.  Introduction of
vma_is_shmem allows detection if tmpfs backed VMAs, so that they may be
used with userfaultfd.  Current implementation presumes usage of
vma_is_shmem only by slow path routines in userfaultfd, therefore the
vma_is_shmem is not made inline to leave the few remaining free bits in
vm_flags.

Link: http://lkml.kernel.org/r/20161216144821.5183-30-aarcange@redhat.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

shmem_mcopy_atomic_pte is the low level routine that implements the
userfaultfd UFFDIO_COPY command.  It is based on the existing
mcopy_atomic_pte routine with modifications for shared memory pages.

Link: http://lkml.kernel.org/r/20161216144821.5183-29-aarcange@redhat.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If __mcopy_atomic_hugetlb exits with an error, put_page will be called
if a huge page was allocated and needs to be freed.  If a reservation
was associated with the huge page, the PagePrivate flag will be set.
Clear PagePrivate before calling put_page/free_huge_page so that the
global reservation count is not incremented.

Link: http://lkml.kernel.org/r/20161216144821.5183-26-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add support for VM_FAULT_RETRY to follow_hugetlb_page() so that
get_user_pages_unlocked/locked and "nonblocking/FOLL_NOWAIT" features
will work on hugetlbfs.

This is required for fully functional userfaultfd non-present support on
hugetlbfs.

Link: http://lkml.kernel.org/r/20161216144821.5183-25-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When processing a hugetlb fault for no page present, check the vma to
determine if faults are to be handled via userfaultfd.  If so, drop the
hugetlb_fault_mutex and call handle_userfault().

Link: http://lkml.kernel.org/r/20161216144821.5183-21-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The new routine copy_huge_page_from_user() uses kmap_atomic() to map
PAGE_SIZE pages.  However, this prevents page faults in the subsequent
call to copy_from_user().  This is OK in the case where the routine is
copied with mmap_sema held.  However, in another case we want to allow
page faults.  So, add a new argument allow_pagefault to indicate if the
routine should allow page faults.

[dan.carpenter@oracle.com: unmap the correct pointer]
  Link: http://lkml.kernel.org/r/20170113082608.GA3548@mwanda
[akpm@linux-foundation.org: kunmap() takes a page*, per Hugh]
Link: http://lkml.kernel.org/r/20161216144821.5183-20-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__mcopy_atomic_hugetlb performs the UFFDIO_COPY operation for huge
pages.  It is based on the existing __mcopy_atomic routine for normal
pages.  Unlike normal pages, there is no huge page support for the
UFFDIO_ZEROPAGE operation.

Link: http://lkml.kernel.org/r/20161216144821.5183-19-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

hugetlb_mcopy_atomic_pte is the low level routine that implements the
userfaultfd UFFDIO_COPY command.  It is based on the existing
mcopy_atomic_pte routine with modifications for huge pages.

Link: http://lkml.kernel.org/r/20161216144821.5183-18-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

userfaultfd UFFDIO_COPY allows user level code to copy data to a page at
fault time.  The data is copied from user space to a newly allocated
huge page.  The new routine copy_huge_page_from_user performs this copy.

Link: http://lkml.kernel.org/r/20161216144821.5183-17-aarcange@redhat.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

MADV_DONTNEED must be notified to userland before the pages are zapped.

This allows userland to immediately stop adding pages to the userfaultfd
ranges before the pages are actually zapped or there could be
non-zeropage leftovers as result of concurrent UFFDIO_COPY run in
between zap_page_range and madvise_userfault_dontneed (both
MADV_DONTNEED and UFFDIO_COPY runs under the mmap_sem for reading, so
they can run concurrently).

Link: http://lkml.kernel.org/r/20161216144821.5183-15-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the page is punched out of the address space the uffd reader should
know this and zeromap the respective area in case of the #PF event.

Link: http://lkml.kernel.org/r/20161216144821.5183-14-aarcange@redhat.comSigned-off-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Optimize the mremap_userfaultfd_complete() interface to pass only the
vm_userfaultfd_ctx pointer through the stack as a microoptimization.

Link: http://lkml.kernel.org/r/20161216144821.5183-13-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The event denotes that an area [start:end] moves to different location.
Length change isn't reported as "new" addresses, if they appear on the
uffd reader side they will not contain any data and the latter can just
zeromap them.

Waiting for the event ACK is also done outside of mmap sem, as for fork
event.

Link: http://lkml.kernel.org/r/20161216144821.5183-12-aarcange@redhat.comSigned-off-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Cleanup the vma->vm_ops usage.

Side note: it would be more robust if vma_is_anonymous() would also
check that vm_flags hasn't VM_PFNMAP set.

Link: http://lkml.kernel.org/r/20161216144821.5183-5-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Higher order requests oom debugging is currently quite hard.  We do have
some compaction points which can tell us how the compaction is operating
but there is no trace point to tell us about compaction retry logic.
This patch adds a one which will have the following format

            bash-3126  [001] ....  1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0

we can see that the order 9 request is not retried even though we are in
the highest compaction priority mode becase the last compaction attempt
was withdrawn.  This means that compaction_zonelist_suitable must have
returned false and there is no suitable zone to compact for this request
and so no need to retry further.

another example would be
           <...>-3137  [001] ....    81.501689: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=failed retries=0 max_retries=16 should_retry=0

in this case the order-9 compaction failed to find any suitable block.
We do not retry anymore because this is a costly request and those do
not go below COMPACT_PRIO_SYNC_LIGHT priority.

Link: http://lkml.kernel.org/r/20161220130135.15719-4-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

should_reclaim_retry is the central decision point for declaring the
OOM.  It might be really useful to expose data used for this decision
making when debugging an unexpected oom situations.

Say we have an OOM report:
[   52.264001] mem_eater invoked oom-killer: gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=0, order=0, oom_score_adj=0
[   52.267549] CPU: 3 PID: 3148 Comm: mem_eater Tainted: G        W       4.8.0-oomtrace3-00006-gb21338b386d2 #1024

Now we can check the tracepoint data to see how we have ended up in this
situation:
       mem_eater-3148  [003] ....    52.432801: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11134 min_wmark=11084 no_progress_loops=1 wmark_check=1
       mem_eater-3148  [003] ....    52.433269: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11103 min_wmark=11084 no_progress_loops=1 wmark_check=1
       mem_eater-3148  [003] ....    52.433712: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11100 min_wmark=11084 no_progress_loops=2 wmark_check=1
       mem_eater-3148  [003] ....    52.434067: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11097 min_wmark=11084 no_progress_loops=3 wmark_check=1
       mem_eater-3148  [003] ....    52.434414: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11094 min_wmark=11084 no_progress_loops=4 wmark_check=1
       mem_eater-3148  [003] ....    52.434761: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11091 min_wmark=11084 no_progress_loops=5 wmark_check=1
       mem_eater-3148  [003] ....    52.435108: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11087 min_wmark=11084 no_progress_loops=6 wmark_check=1
       mem_eater-3148  [003] ....    52.435478: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11084 min_wmark=11084 no_progress_loops=7 wmark_check=0
       mem_eater-3148  [003] ....    52.435478: reclaim_retry_zone: node=0 zone=DMA order=0 reclaimable=0 available=1126 min_wmark=179 no_progress_loops=7 wmark_check=0

The above shows that we can quickly deduce that the reclaim stopped
making any progress (see no_progress_loops increased in each round) and
while there were still some 51 reclaimable pages they couldn't be
dropped for some reason (vmscan trace points would tell us more about
that part).  available will represent reclaimable + free_pages scaled
down per no_progress_loops factor.  This is essentially an optimistic
estimate of how much memory we would have when reclaiming everything.
This can be compared to min_wmark to get a rought idea but the
wmark_check tells the result of the watermark check which is more
precise (includes lowmem reserves, considers the order etc.).  As we can
see no zone is eligible in the end and that is why we have triggered the
oom in this situation.

Please note that higher order requests might fail on the wmark_check
even when there is much more memory available than min_wmark - e.g.
when the memory is fragmented.  A follow up tracepoint will help to
debug those situations.

Link: http://lkml.kernel.org/r/20161220130135.15719-3-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use rb_entry_safe() instead of open-coding it.

Link: http://lkml.kernel.org/r/81bb9820e5b9e4a1c596b3e76f88abf8c4a76cb0.1482221947.git.geliangtang@gmail.comSigned-off-by: NGeliang Tang <geliangtang@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On architectures that allow memory holes, page_is_buddy() has to perform
page_to_pfn() to check for the memory hole.  After the previous patch,
we have the pfn already available in __free_one_page(), which is the
only caller of page_is_buddy(), so move the check there and avoid
page_to_pfn().

Link: http://lkml.kernel.org/r/20161216120009.20064-2-vbabka@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In __free_one_page() we do the buddy merging arithmetics on "page/buddy
index", which is just the lower MAX_ORDER bits of pfn.  The operations
we do that affect the higher bits are bitwise AND and subtraction (in
that order), where the final result will be the same with the higher
bits left unmasked, as long as these bits are equal for both buddies -
which must be true by the definition of a buddy.

We can therefore use pfn's directly instead of "index" and skip the
zeroing of >MAX_ORDER bits.  This can help a bit by itself, although
compiler might be smart enough already.  It also helps the next patch to
avoid page_to_pfn() for memory hole checks.

Link: http://lkml.kernel.org/r/20161216120009.20064-1-vbabka@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tetsuo has been stressing OOM killer path with many parallel allocation
requests when he has noticed that it is not all that hard to swamp
kernel logs with warn_alloc messages caused by allocation stalls.  Even
though the allocation stall message is triggered only once in 10s there
might be many different tasks hitting it roughly around the same time.

A big part of the output is show_mem() which can generate a lot of
output even on a small machines.  There is no reason to show the state
of memory counter for each allocation stall, especially when multiple of
them are reported in a short time period.  Chances are that not much has
changed since the last report.  This patch simply rate limits show_mem
called from warn_alloc to only dump something once per second.  This
should be enough to give us a clue why an allocation might be stalling
while burst of warnings will not swamp log with too much data.

While we are at it, extract all the show_mem related handling (filters)
into a separate function warn_alloc_show_mem.  This will make the code
cleaner and as a bonus point we can distinguish which part of warn_alloc
got throttled due to rate limiting as ___ratelimit dumps the caller.

[akpm@linux-foundation.org: reduce scope of the ratelimit_states]
Link: http://lkml.kernel.org/r/20161215101510.9030-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reported-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Callers of shmem_mapping() are interested in whether the mapping is swap
backed - except for uprobes, which is interested in whether it should
use shmem_read_mapping_page().  All these callers are better served by a
shmem_mapping() which checks for shmem_aops, than the current version
which goes through several indirections to find where the inode lives -
and has the surprising effect that a private mmap of /dev/zero satisfies
both vma_is_anonymous() and shmem_mapping(), when that device node is on
devtmpfs.  I don't think anything in the tree suffers from that
surprise, but it caught me out, and is better fixed.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052148530.13021@eggly.anvilsSigned-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>