The busy tree can be quite big, even though the area is freed or unmapped
it still stays there until "purge" logic removes it.

1) Optimize and reduce the size of "busy" tree by removing a node from
   it right away as soon as user triggers free paths.  It is possible to
   do so, because the allocation is done using another augmented tree.

The vmalloc test driver shows the difference, for example the
"fix_size_alloc_test" is ~11% better comparing with default configuration:

sudo ./test_vmalloc.sh performance

<default>
Summary: fix_size_alloc_test loops: 1000000 avg: 993985 usec
Summary: full_fit_alloc_test loops: 1000000 avg: 973554 usec
Summary: long_busy_list_alloc_test loops: 1000000 avg: 12617652 usec
<default>

<this patch>
Summary: fix_size_alloc_test loops: 1000000 avg: 882263 usec
Summary: full_fit_alloc_test loops: 1000000 avg: 973407 usec
Summary: long_busy_list_alloc_test loops: 1000000 avg: 12593929 usec
<this patch>

2) Since the busy tree now contains allocated areas only and does not
   interfere with lazily free nodes, introduce the new function
   show_purge_info() that dumps "unpurged" areas that is propagated
   through "/proc/vmallocinfo".

3) Eliminate VM_LAZY_FREE flag.

Link: http://lkml.kernel.org/r/20190716152656.12255-2-lpf.vector@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Pengfei Li <lpf.vector@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There is no possibility for memmap to be NULL in the current codebase.

This check was added in commit 95a4774d ("memory-hotplug: update
mce_bad_pages when removing the memory") where memmap was originally
inited to NULL, and only conditionally given a value.

The code that could have passed a NULL has been removed by commit
ba72b4c8

 ("mm/sparsemem: support sub-section hotplug"), so there is no
longer a possibility that memmap can be NULL.

Link: http://lkml.kernel.org/r/20190829035151.20975-1-alastair@d-silva.org
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use the function written to do it instead.

Link: http://lkml.kernel.org/r/20190827053656.32191-2-alastair@au1.ibm.com
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

__pfn_to_section is defined as __nr_to_section(pfn_to_section_nr(pfn)).

Since we already get section_nr, it is not necessary to get mem_section
from start_pfn. By doing so, we reduce one redundant operation.

Link: http://lkml.kernel.org/r/20190809010242.29797-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Tested-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The size argument passed into sparse_buffer_alloc() has already been
aligned with PAGE_SIZE or PMD_SIZE.

If the size after aligned is not power of 2 (e.g.  0x480000), the
PTR_ALIGN() will return wrong value.  Use roundup to round sparsemap_buf
up to next multiple of size.

Link: http://lkml.kernel.org/r/20190705114826.28586-1-lecopzer.chen@mediatek.com
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Mark-PK Tsai <Mark-PK.Tsai@mediatek.com>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sparse_buffer_alloc(xsize) gets the size of memory from sparsemap_buf
after being aligned with the size.  However, the size is at least
PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION) and usually larger
than PAGE_SIZE.

Also, sparse_buffer_fini() only frees memory between sparsemap_buf and
sparsemap_buf_end, since sparsemap_buf may be changed by PTR_ALIGN()
first, the aligned space before sparsemap_buf is wasted and no one will
touch it.

In our ARM32 platform (without SPARSEMEM_VMEMMAP)
  Sparse_buffer_init
    Reserve d359c000 - d3e9c000 (9M)
  Sparse_buffer_alloc
    Alloc   d3a00000 - d3E80000 (4.5M)
  Sparse_buffer_fini
    Free    d3e80000 - d3e9c000 (~=100k)
 The reserved memory between d359c000 - d3a00000 (~=4.4M) is unfreed.

In ARM64 platform (with SPARSEMEM_VMEMMAP)

  sparse_buffer_init
    Reserve ffffffc07d623000 - ffffffc07f623000 (32M)
  Sparse_buffer_alloc
    Alloc   ffffffc07d800000 - ffffffc07f600000 (30M)
  Sparse_buffer_fini
    Free    ffffffc07f600000 - ffffffc07f623000 (140K)
 The reserved memory between ffffffc07d623000 - ffffffc07d800000
 (~=1.9M) is unfreed.

Let's explicit free redundant aligned memory.

[arnd@arndb.de: mark sparse_buffer_free as __meminit]
  Link: http://lkml.kernel.org/r/20190709185528.3251709-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20190705114730.28534-1-lecopzer.chen@mediatek.com
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Mark-PK Tsai <Mark-PK.Tsai@mediatek.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Correct typo in comment.

Link: http://lkml.kernel.org/r/1568233954-3913-1-git-send-email-jrdr.linux@gmail.com
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

walk_system_ram_range() will fail with -EINVAL in case
online_pages_range() was never called (== no resource applicable in the
range).  Otherwise, we will always call online_pages_range() with nr_pages
> 0 and, therefore, have online_pages > 0.

Remove that special handling.

Link: http://lkml.kernel.org/r/20190814154109.3448-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit a9cd410a

 ("mm/page_alloc.c: memory hotplug: free pages as
higher order") assumed that any PFN we get via memory resources is aligned
to to MAX_ORDER - 1, I am not convinced that is always true.  Let's play
safe, check the alignment and fallback to single pages.

akpm: warn in this situation so we get to find out if and why this ever
occurs.

[akpm@linux-foundation.org: add WARN_ON_ONCE()]
Link: http://lkml.kernel.org/r/20190814154109.3448-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

online_pages always corresponds to nr_pages.  Simplify the code, getting
rid of online_pages_blocks().  Add some comments.

Link: http://lkml.kernel.org/r/20190814154109.3448-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

move_pfn_range_to_zone() will set all pages to PG_reserved via
memmap_init_zone().  The only way a page could no longer be reserved would
be if a MEM_GOING_ONLINE notifier would clear PG_reserved - which is not
done (the online_page callback is used for that purpose by e.g., Hyper-V
instead).  walk_system_ram_range() will never call online_pages_range()
with duplicate PFNs, so drop the PageReserved() check.

This seems to be a leftover from ancient times where the memmap was
initialized when adding memory and we wanted to check for already onlined
memory.

Link: http://lkml.kernel.org/r/20190814154109.3448-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "mm/memory_hotplug: online_pages() cleanups", v2.

Some cleanups (+ one fix for a special case) in the context of
online_pages().

This patch (of 5):

This makes it clearer that we will never call func() with duplicate PFNs
in case we have multiple sub-page memory resources.  All unaligned parts
of PFNs are completely discarded.

Link: http://lkml.kernel.org/r/20190814154109.3448-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When offlining a node in try_offline_node(), pgdat is not released.  So
that pgdat could be reused in hotadd_new_pgdat().  While we reallocate
pgdat->per_cpu_nodestats if this pgdat is reused.

This patch prevents the memory leak by just allocating per_cpu_nodestats
when it is a new pgdat.

Link: http://lkml.kernel.org/r/20190813020608.10194-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Each memory block spans the same amount of sections/pages/bytes.  The size
is determined before the first memory block is created.  No need to store
what we can easily calculate - and the calculations even look simpler now.

Michal brought up the idea of variable-sized memory blocks.  However, if
we ever implement something like this, we will need an API compatibility
switch and reworks at various places (most code assumes a fixed memory
block size).  So let's cleanup what we have right now.

While at it, fix the variable naming in register_mem_sect_under_node() -
we no longer talk about a single section.

Link: http://lkml.kernel.org/r/20190809110200.2746-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Let's validate the memory block size early, when initializing the memory
device infrastructure.  Fail hard in case the value is not suitable.

As nobody checks the return value of memory_dev_init(), turn it into a
void function and fail with a panic in all scenarios instead.  Otherwise,
we'll crash later during boot when core/drivers expect that the memory
device infrastructure (including memory_block_size_bytes()) works as
expected.

I think long term, we should move the whole memory block size
configuration (set_memory_block_size_order() and
memory_block_size_bytes()) into drivers/base/memory.c.

Link: http://lkml.kernel.org/r/20190806090142.22709-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Let's rephrase to memory block terminology and add some further
clarifications.

Link: http://lkml.kernel.org/r/20190806080826.5963-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We don't allow to offline memory block devices that belong to multiple
numa nodes.  Therefore, such devices can never get removed.  It is
sufficient to process a single node when removing the memory block.  No
need to iterate over each and every PFN.

We already have the nid stored for each memory block.  Make sure that the
nid always has a sane value.

Please note that checking for node_online(nid) is not required.  If we
would have a memory block belonging to a node that is no longer offline,
then we would have a BUG in the node offlining code.

Link: http://lkml.kernel.org/r/20190719135244.15242-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Let's remove this indirection.  We need the zone in the caller either way,
so let's just detect it there.  Add some documentation for
move_pfn_range_to_zone() instead.

[akpm@linux-foundation.org: restore newline, per David]
Link: http://lkml.kernel.org/r/20190724142324.3686-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Using %px to show the actual address in print_bad_pte()
to help us to debug issue.

Link: http://lkml.kernel.org/r/20190831011816.141002-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem
cache for page table allocations on several architectures that do not use
PAGE_SIZE tables for one or more levels of the page table hierarchy.

Most architectures do not implement these functions and use __weak default
NOP implementation of pgd_cache_init().  Since there is no such default
for pgtable_cache_init(), its empty stub is duplicated among most
architectures.

Rename the definitions of pgd_cache_init() to pgtable_cache_init() and
drop empty stubs of pgtable_cache_init().

Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Will Deacon <will@kernel.org>		[arm64]
Acked-by: Thomas Gleixner <tglx@linutronix.de>	[x86]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The microblaze implementation of pte_alloc_one() has a provision to
allocated PTEs from high memory, but neither CONFIG_HIGHPTE nor pte_map*()
versions for suitable for HIGHPTE are defined.

Except that, microblaze version of pte_alloc_one() is identical to the
generic one as well as the implementations of pte_free() and
pte_free_kernel().

Switch microblaze to use the generic versions of these functions.  Also
remove pte_free_slow() that is not referenced anywhere in the code.

Link: http://lkml.kernel.org/r/1565690952-32158-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The sh implementation pte_alloc_one(), pte_alloc_one_kernel(),
pte_free_kernel() and pte_free() is identical to the generic except of
lack of __GFP_ACCOUNT for the user PTEs allocation.

Switch sh to use generic version of these functions.

Link: http://lkml.kernel.org/r/1565250728-21721-4-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The ia64 implementation pte_alloc_one(), pte_alloc_one_kernel(),
pte_free_kernel() and pte_free() is identical to the generic except of
lack of __GFP_ACCOUNT for the user PTEs allocation.

Switch ia64 to use generic version of these functions.

Link: http://lkml.kernel.org/r/1565250728-21721-3-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "mm: remove quicklist page table caches".

A while ago Nicholas proposed to remove quicklist page table caches [1].

I've rebased his patch on the curren upstream and switched ia64 and sh to
use generic versions of PTE allocation.

[1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

This patch (of 3):

Remove page table allocator "quicklists".  These have been around for a
long time, but have not got much traction in the last decade and are only
used on ia64 and sh architectures.

The numbers in the initial commit look interesting but probably don't
apply anymore.  If anybody wants to resurrect this it's in the git
history, but it's unhelpful to have this code and divergent allocator
behaviour for minor archs.

Also it might be better to instead make more general improvements to page
allocator if this is still so slow.

Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In our testing (camera recording), Miguel and Wei found
unmap_page_range() takes above 6ms with preemption disabled easily.
When I see that, the reason is it holds page table spinlock during
entire 512 page operation in a PMD.  6.2ms is never trivial for user
experince if RT task couldn't run in the time because it could make
frame drop or glitch audio problem.

I had a time to benchmark it via adding some trace_printk hooks between
pte_offset_map_lock and pte_unmap_unlock in zap_pte_range.  The testing
device is 2018 premium mobile device.

I can get 2ms delay rather easily to release 2M(ie, 512 pages) when the
task runs on little core even though it doesn't have any IPI and LRU
lock contention.  It's already too heavy.

If I remove activate_page, 35-40% overhead of zap_pte_range is gone so
most of overhead(about 0.7ms) comes from activate_page via
mark_page_accessed.  Thus, if there are LRU contention, that 0.7ms could
accumulate up to several ms.

So this patch adds a check for need_resched() in the loop, and a
preemption point if necessary.

Link: http://lkml.kernel.org/r/20190731061440.GC155569@google.com
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Miguel de Dios <migueldedios@google.com>
Reported-by: Wei Wang <wvw@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since ptent will not be changed after previous assignment of entry, it is
not necessary to do the assignment again.

Link: http://lkml.kernel.org/r/20190708082740.21111-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in fc1d8e7c

 ("mm:
introduce put_user_page*(), placeholder versions").

Link: http://lkml.kernel.org/r/20190724044537.10458-4-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Cc: Björn Töpel <bjorn.topel@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in fc1d8e7c

 ("mm:
introduce put_user_page*(), placeholder versions").

Also reverse the order of a comparison, in order to placate checkpatch.pl.

Link: http://lkml.kernel.org/r/20190724044537.10458-3-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[11~From: John Hubbard <jhubbard@nvidia.com>
Subject: mm/gup: add make_dirty arg to put_user_pages_dirty_lock()

Patch series "mm/gup: add make_dirty arg to put_user_pages_dirty_lock()",
v3.

There are about 50+ patches in my tree [2], and I'll be sending out the
remaining ones in a few more groups:

* The block/bio related changes (Jerome mostly wrote those, but I've had
  to move stuff around extensively, and add a little code)

* mm/ changes

* other subsystem patches

* an RFC that shows the current state of the tracking patch set.  That
  can only be applied after all call sites are converted, but it's good to
  get an early look at it.

This is part a tree-wide conversion, as described in fc1d8e7c

 ("mm:
introduce put_user_page*(), placeholder versions").

This patch (of 3):

Provide more capable variation of put_user_pages_dirty_lock(), and delete
put_user_pages_dirty().  This is based on the following:

1.  Lots of call sites become simpler if a bool is passed into
   put_user_page*(), instead of making the call site choose which
   put_user_page*() variant to call.

2.  Christoph Hellwig's observation that set_page_dirty_lock() is
   usually correct, and set_page_dirty() is usually a bug, or at least
   questionable, within a put_user_page*() calling chain.

This leads to the following API choices:

    * put_user_pages_dirty_lock(page, npages, make_dirty)

    * There is no put_user_pages_dirty(). You have to
      hand code that, in the rare case that it's
      required.

[jhubbard@nvidia.com: remove unused variable in siw_free_plist()]
  Link: http://lkml.kernel.org/r/20190729074306.10368-1-jhubbard@nvidia.com
Link: http://lkml.kernel.org/r/20190724044537.10458-2-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

One of our services observed a high rate of cgroup OOM kills in the
presence of large amounts of clean cache.  Debugging showed that the
culprit is the shared cgroup iteration in page reclaim.

Under high allocation concurrency, multiple threads enter reclaim at the
same time.  Fearing overreclaim when we first switched from the single
global LRU to cgrouped LRU lists, we introduced a shared iteration state
for reclaim invocations - whether 1 or 20 reclaimers are active
concurrently, we only walk the cgroup tree once: the 1st reclaimer
reclaims the first cgroup, the second the second one etc.  With more
reclaimers than cgroups, we start another walk from the top.

This sounded reasonable at the time, but the problem is that reclaim
concurrency doesn't scale with allocation concurrency.  As reclaim
concurrency increases, the amount of memory individual reclaimers get to
scan gets smaller and smaller.  Individual reclaimers may only see one
cgroup per cycle, and that may not have much reclaimable memory.  We see
individual reclaimers declare OOM when there is plenty of reclaimable
memory available in cgroups they didn't visit.

This patch does away with the shared iterator, and every reclaimer is
allowed to scan the full cgroup tree and see all of reclaimable memory,
just like it would on a non-cgrouped system.  This way, when OOM is
declared, we know that the reclaimer actually had a chance.

To still maintain fairness in reclaim pressure, disallow cgroup reclaim
from bailing out of the tree walk early.  Kswapd and regular direct
reclaim already don't bail, so it's not clear why limit reclaim would have
to, especially since it only walks subtrees to begin with.

This change completely eliminates the OOM kills on our service, while
showing no signs of overreclaim - no increased scan rates, %sys time, or
abrupt free memory spikes.  I tested across 100 machines that have 64G of
RAM and host about 300 cgroups each.

[ It's possible overreclaim never was a *practical* issue to begin
  with - it was simply a concern we had on the mailing lists at the
  time, with no real data to back it up. But we have also added more
  bail-out conditions deeper inside reclaim (e.g. the proportional
  exit in shrink_node_memcg) since. Regardless, now we have data that
  suggests full walks are more reliable and scale just fine. ]

Link: http://lkml.kernel.org/r/20190812192316.13615-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
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>

Commit 72f0184c

 ("mm, memcg: remove hotplug locking from try_charge")
introduced css_tryget()/css_put() calls in drain_all_stock(), which are
supposed to protect the target memory cgroup from being released during
the mem_cgroup_is_descendant() call.

However, it's not completely safe.  In theory, memcg can go away between
reading stock->cached pointer and calling css_tryget().

This can happen if drain_all_stock() races with drain_local_stock()
performed on the remote cpu as a result of a work, scheduled by the
previous invocation of drain_all_stock().

The race is a bit theoretical and there are few chances to trigger it, but
the current code looks a bit confusing, so it makes sense to fix it
anyway.  The code looks like as if css_tryget() and css_put() are used to
protect stocks drainage.  It's not necessary because stocked pages are
holding references to the cached cgroup.  And it obviously won't work for
works, scheduled on other cpus.

So, let's read the stock->cached pointer and evaluate the memory cgroup
inside a rcu read section, and get rid of css_tryget()/css_put() calls.

Link: http://lkml.kernel.org/r/20190802192241.3253165-1-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
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>

We're trying to use memory.high to limit workloads, but have found that
containment can frequently fail completely and cause OOM situations
outside of the cgroup.  This happens especially with swap space -- either
when none is configured, or swap is full.  These failures often also don't
have enough warning to allow one to react, whether for a human or for a
daemon monitoring PSI.

Here is output from a simple program showing how long it takes in usec
(column 2) to allocate a megabyte of anonymous memory (column 1) when a
cgroup is already beyond its memory high setting, and no swap is
available:

    [root@ktst ~]# systemd-run -p MemoryHigh=100M -p MemorySwapMax=1 \
    > --wait -t timeout 300 /root/mdf
    [...]
    95  1035
    96  1038
    97  1000
    98  1036
    99  1048
    100 1590
    101 1968
    102 1776
    103 1863
    104 1757
    105 1921
    106 1893
    107 1760
    108 1748
    109 1843
    110 1716
    111 1924
    112 1776
    113 1831
    114 1766
    115 1836
    116 1588
    117 1912
    118 1802
    119 1857
    120 1731
    [...]
    [System OOM in 2-3 seconds]

The delay does go up extremely marginally past the 100MB memory.high
threshold, as now we spend time scanning before returning to usermode, but
it's nowhere near enough to contain growth.  It also doesn't get worse the
more pages you have, since it only considers nr_pages.

The current situation goes against both the expectations of users of
memory.high, and our intentions as cgroup v2 developers.  In
cgroup-v2.txt, we claim that we will throttle and only under "extreme
conditions" will memory.high protection be breached.  Likewise, cgroup v2
users generally also expect that memory.high should throttle workloads as
they exceed their high threshold.  However, as seen above, this isn't
always how it works in practice -- even on banal setups like those with no
swap, or where swap has become exhausted, we can end up with memory.high
being breached and us having no weapons left in our arsenal to combat
runaway growth with, since reclaim is futile.

It's also hard for system monitoring software or users to tell how bad the
situation is, as "high" events for the memcg may in some cases be benign,
and in others be catastrophic.  The current status quo is that we fail
containment in a way that doesn't provide any advance warning that things
are about to go horribly wrong (for example, we are about to invoke the
kernel OOM killer).

This patch introduces explicit throttling when reclaim is failing to keep
memcg size contained at the memory.high setting.  It does so by applying
an exponential delay curve derived from the memcg's overage compared to
memory.high.  In the normal case where the memcg is either below or only
marginally over its memory.high setting, no throttling will be performed.

This composes well with system health monitoring and remediation, as these
allocator delays are factored into PSI's memory pressure calculations.
This both creates a mechanism system administrators or applications
consuming the PSI interface to trivially see that the memcg in question is
struggling and use that to make more reasonable decisions, and permits
them enough time to act.  Either of these can act with significantly more
nuance than that we can provide using the system OOM killer.

This is a similar idea to memory.oom_control in cgroup v1 which would put
the cgroup to sleep if the threshold was violated, but it's also
significantly improved as it results in visible memory pressure, and also
doesn't schedule indefinitely, which previously made tracing and other
introspection difficult (ie.  it's clamped at 2*HZ per allocation through
MEMCG_MAX_HIGH_DELAY_JIFFIES).

Contrast the previous results with a kernel with this patch:

    [root@ktst ~]# systemd-run -p MemoryHigh=100M -p MemorySwapMax=1 \
    > --wait -t timeout 300 /root/mdf
    [...]
    95  1002
    96  1000
    97  1002
    98  1003
    99  1000
    100 1043
    101 84724
    102 330628
    103 610511
    104 1016265
    105 1503969
    106 2391692
    107 2872061
    108 3248003
    109 4791904
    110 5759832
    111 6912509
    112 8127818
    113 9472203
    114 12287622
    115 12480079
    116 14144008
    117 15808029
    118 16384500
    119 16383242
    120 16384979
    [...]

As you can see, in the normal case, memory allocation takes around 1000
usec.  However, as we exceed our memory.high, things start to increase
exponentially, but fairly leniently at first.  Our first megabyte over
memory.high takes us 0.16 seconds, then the next is 0.46 seconds, then the
next is almost an entire second.  This gets worse until we reach our
eventual 2*HZ clamp per batch, resulting in 16 seconds per megabyte.
However, this is still making forward progress, so permits tracing or
further analysis with programs like GDB.

We use an exponential curve for our delay penalty for a few reasons:

1. We run mem_cgroup_handle_over_high to potentially do reclaim after
   we've already performed allocations, which means that temporarily
   going over memory.high by a small amount may be perfectly legitimate,
   even for compliant workloads. We don't want to unduly penalise such
   cases.
2. An exponential curve (as opposed to a static or linear delay) allows
   ramping up memory pressure stats more gradually, which can be useful
   to work out that you have set memory.high too low, without destroying
   application performance entirely.

This patch expands on earlier work by Johannes Weiner. Thanks!

[akpm@linux-foundation.org: fix max() warning]
[akpm@linux-foundation.org: fix __udivdi3 ref on 32-bit]
[akpm@linux-foundation.org: fix it even more]
[chris@chrisdown.name: fix 64-bit divide even more]
Link: http://lkml.kernel.org/r/20190723180700.GA29459@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Transparent Huge Pages are currently stored in i_pages as pointers to
consecutive subpages.  This patch changes that to storing consecutive
pointers to the head page in preparation for storing huge pages more
efficiently in i_pages.

Large parts of this are "inspired" by Kirill's patch
https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@linux.intel.com/

Kirill and Huang Ying contributed several fixes.

[willy@infradead.org: use compound_nr, squish uninit-var warning]
Link: http://lkml.kernel.org/r/20190731210400.7419-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>
Reviewed-by: Kirill Shutemov <kirill@shutemov.name>
Reviewed-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Tested-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Tested-by: Qian Cai <cai@lca.pw>
Tested-by: Mikhail Gavrilo...

This actually checks that writeback is needed or in progress.

Link: http://lkml.kernel.org/r/156378817069.1087.1302816672037672488.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Functions like filemap_write_and_wait_range() should do nothing if inode
has no dirty pages or pages currently under writeback.  But they anyway
construct struct writeback_control and this does some atomic operations if
CONFIG_CGROUP_WRITEBACK=y - on fast path it locks inode->i_lock and
updates state of writeback ownership, on slow path might be more work.
Current this path is safely avoided only when inode mapping has no pages.

For example generic_file_read_iter() calls filemap_write_and_wait_range()
at each O_DIRECT read - pretty hot path.

This patch skips starting new writeback if mapping has no dirty tags set.
If writeback is already in progress filemap_write_and_wait_range() will
wait for it.

Link: http://lkml.kernel.org/r/156378816804.1087.8607636317907921438.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The debug_pagealloc functionality is useful to catch buggy page allocator
users that cause e.g.  use after free or double free.  When page
inconsistency is detected, debugging is often simpler by knowing the call
stack of process that last allocated and freed the page.  When page_owner
is also enabled, we record the allocation stack trace, but not freeing.

This patch therefore adds recording of freeing process stack trace to page
owner info, if both page_owner and debug_pagealloc are configured and
enabled.  With only page_owner enabled, this info is not useful for the
memory leak debugging use case.  dump_page() is adjusted to print the
info.  An example result of calling __free_pages() twice may look like
this (note the page last free stack trace):

BUG: Bad page state in process bash  pfn:13d8f8
page:ffffc31984f63e00 refcount:-1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x1affff800000000()
raw: 01affff800000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 ffffffffffffffff 0000000000000000
page dumped because: nonzero _refcount
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xcc0(GFP_KERNEL)
 prep_new_page+0x143/0x150
 get_page_from_freelist+0x289/0x380
 __alloc_pages_nodemask+0x13c/0x2d0
 khugepaged+0x6e/0xc10
 kthread+0xf9/0x130
 ret_from_fork+0x3a/0x50
page last free stack trace:
 free_pcp_prepare+0x134/0x1e0
 free_unref_page+0x18/0x90
 khugepaged+0x7b/0xc10
 kthread+0xf9/0x130
 ret_from_fork+0x3a/0x50
Modules linked in:
CPU: 3 PID: 271 Comm: bash Not tainted 5.3.0-rc4-2.g07a1a73-default+ #57
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014
Call Trace:
 dump_stack+0x85/0xc0
 bad_page.cold+0xba/0xbf
 rmqueue_pcplist.isra.0+0x6c5/0x6d0
 rmqueue+0x2d/0x810
 get_page_from_freelist+0x191/0x380
 __alloc_pages_nodemask+0x13c/0x2d0
 __get_free_pages+0xd/0x30
 __pud_alloc+0x2c/0x110
 copy_page_range+0x4f9/0x630
 dup_mmap+0x362/0x480
 dup_mm+0x68/0x110
 copy_process+0x19e1/0x1b40
 _do_fork+0x73/0x310
 __x64_sys_clone+0x75/0x80
 do_syscall_64+0x6e/0x1e0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f10af854a10
...

Link: http://lkml.kernel.org/r/20190820131828.22684-5-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For debugging purposes it might be useful to keep the owner info even
after page has been freed, and include it in e.g.  dump_page() when
detecting a bad page state.  For that, change the PAGE_EXT_OWNER flag
meaning to "page owner info has been set at least once" and add new
PAGE_EXT_OWNER_ACTIVE for tracking whether page is supposed to be
currently tracked allocated or free.  Adjust dump_page() accordingly,
distinguishing free and allocated pages.  In the page_owner debugfs file,
keep printing only allocated pages so that existing scripts are not
confused, and also because free pages are irrelevant for the memory
statistics or leak detection that's the typical use case of the file,
anyway.

Link: http://lkml.kernel.org/r/20190820131828.22684-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "debug_pagealloc improvements through page_owner", v2.

The debug_pagealloc functionality serves a similar purpose on the page
allocator level that slub_debug does on the kmalloc level, which is to
detect bad users.  One notable feature that slub_debug has is storing
stack traces of who last allocated and freed the object.  On page level we
track allocations via page_owner, but that info is discarded when freeing,
and we don't track freeing at all.  This series improves those aspects.
With both debug_pagealloc and page_owner enabled, we can then get bug
reports such as the example in Patch 4.

SLUB debug tracking additionally stores cpu, pid and timestamp.  This could
be added later, if deemed useful enough to justify the additional page_ext
structure size.

This patch (of 3):

Currently, page owner info is only recorded for the first page of a
high-order allocation, and copied to tail pages in the event of a split
page.  With the plan to keep previous owner info after freeing the page,
it would be benefical to record page owner for each subpage upon
allocation.  This increases the overhead for high orders, but that should
be acceptable for a debugging option.

The order stored for each subpage is the order of the whole allocation.
This makes it possible to calculate the "head" pfn and to recognize "tail"
pages (quoted because not all high-order allocations are compound pages
with true head and tail pages).  When reading the page_owner debugfs file,
keep skipping the "tail" pages so that stats gathered by existing scripts
don't get inflated.

Link: http://lkml.kernel.org/r/20190820131828.22684-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is a cleanup patch that replaces two historical uses of
list_move_tail() with relatively recent add_page_to_lru_list_tail().

Link: http://lkml.kernel.org/r/20190716212436.7137-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ira Weiny <ira.weiny@intel.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>