When kswapd is awake reclaiming, the per-cpu stat thresholds are lowered
to get more accurate counts to avoid breaching watermarks.  This
threshold update iterates over all possible CPUs which is unnecessary.
Only online CPUs need to be updated.  If a new CPU is onlined,
refresh_zone_stat_thresholds() will set the thresholds correctly.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

zone->pages_scanned is a write-intensive cache line during page reclaim
and it's also updated during page free.  Move the counter into vmstat to
take advantage of the per-cpu updates and do not update it in the free
paths unless necessary.

On a small UMA machine running tiobench the difference is marginal.  On
a 4-node machine the overhead is more noticable.  Note that automatic
NUMA balancing was disabled for this test as otherwise the system CPU
overhead is unpredictable.

          3.16.0-rc3  3.16.0-rc3  3.16.0-rc3
             vanillarearrange-v5   vmstat-v5
User          746.94      759.78      774.56
System      65336.22    58350.98    32847.27
Elapsed     27553.52    27282.02    27415.04

Note that the overhead reduction will vary depending on where exactly
pages are allocated and freed.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The arrangement of struct zone has changed over time and now it has
reached the point where there is some inappropriate sharing going on.
On x86-64 for example

o The zone->node field is shared with the zone lock and zone->node is
  accessed frequently from the page allocator due to the fair zone
  allocation policy.

o span_seqlock is almost never used by shares a line with free_area

o Some zone statistics share a cache line with the LRU lock so
  reclaim-intensive and allocator-intensive workloads can bounce the cache
  line on a stat update

This patch rearranges struct zone to put read-only and read-mostly
fields together and then splits the page allocator intensive fields, the
zone statistics and the page reclaim intensive fields into their own
cache lines.  Note that the type of lowmem_reserve changes due to the
watermark calculations being signed and avoiding a signed/unsigned
conversion there.

On the test configuration I used the overall size of struct zone shrunk
by one cache line.  On smaller machines, this is not likely to be
noticable.  However, on a 4-node NUMA machine running tiobench the
system CPU overhead is reduced by this patch.

          3.16.0-rc3  3.16.0-rc3
             vanillarearrange-v5r9
User          746.94      759.78
System      65336.22    58350.98
Elapsed     27553.52    27282.02
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This was formerly the series "Improve sequential read throughput" which
noted some major differences in performance of tiobench since 3.0.
While there are a number of factors, two that dominated were the
introduction of the fair zone allocation policy and changes to CFQ.

The behaviour of fair zone allocation policy makes more sense than
tiobench as a benchmark and CFQ defaults were not changed due to
insufficient benchmarking.

This series is what's left.  It's one functional fix to the fair zone
allocation policy when used on NUMA machines and a reduction of overhead
in general.  tiobench was used for the comparison despite its flaws as
an IO benchmark as in this case we are primarily interested in the
overhead of page allocator and page reclaim activity.

On UMA, it makes little difference to overhead

          3.16.0-rc3   3.16.0-rc3
             vanilla lowercost-v5
User          383.61      386.77
System        403.83      401.74
Elapsed      5411.50     5413.11

On a 4-socket NUMA machine it's a bit more noticable

          3.16.0-rc3   3.16.0-rc3
             vanilla lowercost-v5
User          746.94      802.00
System      65336.22    40852.33
Elapsed     27553.52    27368.46

This patch (of 6):

The LRU insertion and activate tracepoints take PFN as a parameter
forcing the overhead to the caller.  Move the overhead to the tracepoint
fast-assign method to ensure the cost is only incurred when the
tracepoint is active.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Until now, the reporting from trace-vmscan-postprocess.pl is not very
useful because we cannot directly use this script for checking the
file/anon ratio of scanning.  This patch aims to report respectively the
number of file/anon pages which were scanned/reclaimed by kswapd or
direct-reclaim.  Sample output is usually something like the following.

Summary
Direct reclaims:                          8823
Direct reclaim pages scanned:             2438797
Direct reclaim file pages scanned:        1315200
Direct reclaim anon pages scanned:        1123597
Direct reclaim pages reclaimed:           446139
Direct reclaim file pages reclaimed:      378668
Direct reclaim anon pages reclaimed:      67471
Direct reclaim write file sync I/O:       0
Direct reclaim write anon sync I/O:       0
Direct reclaim write file async I/O:      0
Direct reclaim write anon async I/O:      4240
Wake kswapd requests:                     122310
Time stalled direct reclaim:              13.78 seconds

Kswapd wakeups:                           25817
Kswapd pages scanned:                     170779115
Kswapd file pages scanned:                162725123
Kswapd anon pages scanned:                8053992
Kswapd pages reclaimed:                   129065738
Kswapd file pages reclaimed:              128500930
Kswapd anon pages reclaimed:              564808
Kswapd reclaim write file sync I/O:       0
Kswapd reclaim write anon sync I/O:       0
Kswapd reclaim write file async I/O:      36
Kswapd reclaim write anon async I/O:      730730
Time kswapd awake:                        1015.50 seconds
Signed-off-by: NChen Yucong <slaoub@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

vm_total_pages is calculated by nr_free_pagecache_pages(), which counts
the number of pages which are beyond the high watermark within all
zones.  So vm_total_pages is not equal to total number of pages which
the VM controls.
Signed-off-by: NWang Sheng-Hui <shhuiw@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.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>

Otherwise we may not notice that pte was softdirty because
pte_mksoft_dirty helper _returns_ new pte but doesn't modify the
argument.

In case if page fault happend on dirty filemapping the newly created pte
may loose softdirty bit thus if a userspace program is tracking memory
changes with help of a memory tracker (CONFIG_MEM_SOFT_DIRTY) it might
miss modification of a memory page (which in worts case may lead to data
inconsistency).
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Acked-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When limiting memory by mem= and ACPI DSDT table has PNP0C80,
firmware_map_entrys of same memory range are allocated and memmap X
sysfses which have same memory range are created as follows:

  # cat /sys/firmware/memmap/0/*
  0x407ffffffff
  0x40000000000
  System RAM
  # cat /sys/firmware/memmap/33/*
  0x407ffffffff
  0x40000000000
  System RAM
  # cat /sys/firmware/memmap/35/*
  0x407ffffffff
  0x40000000000
  System RAM

In this case, when hot-removing memory, kernel panic occurs, showing
following call trace:

  BUG: unable to handle kernel paging request at 00000001003e000b
  IP: sysfs_open_file+0x46/0x2b0
  PGD 203a89fe067 PUD 0
  Oops: 0000 [#1] SMP
  ...
  Call Trace:
    do_dentry_open+0x1ef/0x2a0
    finish_open+0x31/0x40
    do_last+0x57c/0x1220
    path_openat+0xc2/0x4c0
    do_filp_open+0x4b/0xb0
    do_sys_open+0xf3/0x1f0
    SyS_open+0x1e/0x20
    system_call_fastpath+0x16/0x1b

The problem occurs as follows:

When calling e820_reserve_resources(), firmware_map_entrys of all e820
memory map are allocated.  And all firmware_map_entrys is added
map_entries list as follows:

map_entries
 -> +--- entry A --------+ -> ...
    | start 0x407ffffffff|
    | end   0x40000000000|
    | type  System RAM   |
    +--------------------+

After that, if ACPI DSDT table has PNP0C80 and the memory range is
limited by mem=, the PNP0C80 is hot-added.  Then firmware_map_entry of
PNP0C80 is allocated and added map_entries list as follows:

map_entries
 -> +--- entry A --------+ -> ... -> +--- entry B --------+
    | start 0x407ffffffff|           | start 0x407ffffffff|
    | end   0x40000000000|           | end   0x40000000000|
    | type  System RAM   |           | type  System RAM   |
    +--------------------+           +--------------------+

Then memmap 0 sysfs for entry B is created.

After that, firmware_memmap_init() creates memmap sysfses of all
firmware_map_entrys in map_entries list.  As a result, memmap 33 sysfs
for entry A and memmap 35 sysfs for entry B are created.  But kobject of
entry B has been used by memmap 0 sysfs.  So when creating memmap 35
sysfs, the kobject is broken.

If hot-removing memory, memmap 0 sysfs is destroyed and kobject of
memmap 0 sysfs is freed.  But the kobject can be accessed via memmap 35
sysfs.  So when open memmap 35 sysfs, kernel panic occurs.

This patch checks whether there is firmware_map_entry of same memory
range in map_entries list and don't allocate firmware_map_entry of same
memroy range.
Signed-off-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

firmware_map_add_hotplug() calls firmware_map_find_entry_bootmem() to
get free firmware_map_entry.  But end arguments is not correct.  So
firmware_map_find_entry_bootmem() cannot not find firmware_map_entry.

The patch passes the correct end argument to firmware_map_find_entry_bootmem().
Signed-off-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently map_vm_area() takes (struct page *** pages) as third argument,
and after mapping, it moves (*pages) to point to (*pages +
nr_mappped_pages).

It looks like this kind of increment is useless to its caller these
days.  The callers don't care about the increments and actually they're
trying to avoid this by passing another copy to map_vm_area().

The caller can always guarantee all the pages can be mapped into vm_area
as specified in first argument and the caller only cares about whether
map_vm_area() fails or not.

This patch cleans up the pointer movement in map_vm_area() and updates
its callers accordingly.
Signed-off-by: NWANG Chao <chaowang@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 71e3aac0 ("thp: transparent hugepage core") adds
copy_pte_range prototype to huge_mm.h.  I'm not sure why (or if) this
function have been used outside of memory.c, but it currently isn't.
This patch makes copy_pte_range() static again.
Signed-off-by: NJerome Marchand <jmarchan@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

They are unnecessary: "zero" can be used in place of "hugetlb_zero" and
passing extra2 == NULL is equivalent to infinity.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: NLuiz Capitulino <lcapitulino@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>

Three different interfaces alter the maximum number of hugepages for an
hstate:

 - /proc/sys/vm/nr_hugepages for global number of hugepages of the default
   hstate,

 - /sys/kernel/mm/hugepages/hugepages-X/nr_hugepages for global number of
   hugepages for a specific hstate, and

 - /sys/kernel/mm/hugepages/hugepages-X/nr_hugepages/mempolicy for number of
   hugepages for a specific hstate over the set of allowed nodes.

Generalize the code so that a single function handles all of these
writes instead of duplicating the code in two different functions.

This decreases the number of lines of code, but also reduces the size of
.text by about half a percent since set_max_huge_pages() can be inlined.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: NLuiz Capitulino <lcapitulino@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Acked-by: NDavidlohr Bueso <davidlohr@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When a hwpoison page is locked it could change state due to parallel
modifications.  The original compound page can be torn down and then
this 4k page becomes part of a differently-size compound page is is a
standalone regular page.

Check after the lock if the page is still the same compound page.

We could go back, grab the new head page and try again but it should be
quite rare, so I thought this was safest.  A retry loop would be more
difficult to test and may have more side effects.

The hwpoison code by design only tries to handle cases that are
reasonably common in workloads, as visible in page-flags.

I'm not really that concerned about handling this (likely rare case),
just not crashing on it.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When returning from hugetlb_cow(), we always (1) put back the refcount
for each referenced page -- always 'old', and 'new' if allocation was
successful.  And (2) retake the page table lock right before returning,
as the callers expects.  This logic can be simplified and encapsulated,
as proposed in this patch.  In addition to cleaner code, we also shave a
few bytes off the instruction text:

   text    data     bss     dec     hex filename
  28399     462   41328   70189   1122d mm/hugetlb.o-baseline
  28367     462   41328   70157   1120d mm/hugetlb.o-patched

Passes libhugetlbfs testcases.
Signed-off-by: NDavidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This function always returns 1, thus no need to check return value in
hugetlb_cow().  By doing so, we can get rid of the unnecessary WARN_ON
call.  While this logic perhaps existed as a way of identifying future
unmap_ref_private() mishandling, reality is it serves no apparent
purpose.
Signed-off-by: NDavidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Do we really need an exported alias for __SetPageReferenced()? Its
callers better know what they're doing, in which case the page would not
be already marked referenced.  Kill init_page_accessed(), just
__SetPageReferenced() inline.
Signed-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Prabhakar Lad <prabhakar.csengg@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix checkpatch warning:
  "WARNING: debugfs_remove_recursive(NULL) is safe this check is probably not required"
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Acked-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Historically, we exported shared pages to userspace via sysinfo(2)
sharedram and /proc/meminfo's "MemShared" fields.  With the advent of
tmpfs, from kernel v2.4 onward, that old way for accounting shared mem
was deemed inaccurate and we started to export a hard-coded 0 for
sysinfo.sharedram.  Later on, during the 2.6 timeframe, "MemShared" got
re-introduced to /proc/meminfo re-branded as "Shmem", but we're still
reporting sysinfo.sharedmem as that old hard-coded zero, which makes the
"shared memory" report inconsistent across interfaces.

This patch leverages the addition of explicit accounting for pages used
by shmem/tmpfs -- "4b02108a mm: oom analysis: add shmem vmstat" -- in
order to make the users of sysinfo(2) and si_meminfo*() friends aware of
that vmstat entry and make them report it consistently across the
interfaces, as well to make sysinfo(2) returned data consistent with our
current API documentation states.
Signed-off-by: NRafael Aquini <aquini@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.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>

Print a warning (if CONFIG_DEBUG_VM=y) when memory commitment becomes
too negative.

This shouldn't happen any more - the previous two patches fixed the
committed_as underflow issues.

[akpm@linux-foundation.org: use VM_WARN_ONCE, per Dave]
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A shared anonymous mapping created without MAP_NORESERVE holds memory
reservation for whole range of shmem segment.  Usually there is no way
to change its size, but /proc/<pid>/map_files/...  (available if
CONFIG_CHECKPOINT_RESTORE=y) allows that.

This patch adjusts the memory reservation in shmem_setattr().
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If __shmem_file_setup() fails on struct file allocation it uncharges
memory commitment twice: first by shmem_unacct_size() and second time
implicitly in shmem_evict_inode() when it kills the newly created inode.

This patch removes shmem_unacct_size() from error path if the inode was
already there.
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It was missing...

Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.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>

tmp_mask in the __vmalloc_area_node() iteration never changes so it can
be moved into function scope and marked with const.  This causes the
movl and orl to only be done once per call rather than area->nr_pages
times.

nested_gfp can also be marked const.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is not uncommon on busy servers to get stuck hundred of ms in
vmalloc() calls (like file descriptor expansions).

Add a cond_resched() to __vmalloc_area_node() to be gentle to
other tasks.

[akpm@linux-foundation.org: only do it for __GFP_WAIT, per David]
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, we have more filesystems supporting fallocate, e.g
ext4/btrfs.  Remove the outdated comment for madvise_remove.
Signed-off-by: NWang Sheng-Hui <shhuiw@gmail.com>
Reviewed-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The mm_migrate_pages trace event reports a reason for the migration,
typically as a symbolic string.  The exception is the reason
MR_NUMA_MISPLACED for which it just displays the numeric value:
mm_migrate_pages: nr_succeeded=1 nr_failed=0 mode=MIGRATE_ASYNC
reason=0x5

This patch makes the output consistent by introducing a string value for
MR_NUMA_MISPLACED.  The event is then reported as: mm_migrate_pages:
nr_succeeded=1 nr_failed=0 mode=MIGRATE_ASYNC reason=numa_misplaced
Signed-off-by: NMax Asbock <masbock@linux.vnet.ibm.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reorder the members by input and output, then turn the individual
integers for may_writepage, may_unmap, may_swap, compaction_ready,
hibernation_mode into bit fields to save stack space:

  +72/-296 -224
  kswapd                                       104     176     +72
  try_to_free_pages                             80      56     -24
  try_to_free_mem_cgroup_pages                  80      56     -24
  shrink_all_memory                             88      64     -24
  reclaim_clean_pages_from_list                168     144     -24
  mem_cgroup_shrink_node_zone                  104      80     -24
  __zone_reclaim                               176     152     -24
  balance_pgdat                                152       -    -152
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Swappiness is determined for each scanned memcg individually in
shrink_zone() and is not a parameter that applies throughout the reclaim
scan.  Move it out of struct scan_control to prevent accidental use of a
stale value.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Direct reclaim currently calls shrink_zones() to reclaim all members of
a zonelist, and if that wasn't successful it does another pass through
the same zonelist to check overall reclaimability.

Just check reclaimability in shrink_zones() directly and propagate the
result through the return value.  Then remove all_unreclaimable().
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Page reclaim for a higher-order page runs until compaction is ready,
then aborts and signals this situation through the return value of
shrink_zones().  This is an oddly specific signal to encode in the
return value of shrink_zones(), though, and can be quite confusing.

Introduce sc->compaction_ready and signal the compactability of the
zones out-of-band to free up the return value of shrink_zones() for
actual zone reclaimability.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

shrink_zones() has a special branch to skip the all_unreclaimable()
check during hibernation, because a frozen kswapd can't mark a zone
unreclaimable.

But ever since commit 6e543d57 ("mm: vmscan: fix
do_try_to_free_pages() livelock"), determining a zone to be
unreclaimable is done by directly looking at its scan history and no
longer relies on kswapd setting the per-zone flag.

Remove this branch and let shrink_zones() check the reclaimability of
the target zones regardless of hibernation state.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <Kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In original code, zone_movable_is_highmem() assumes ZONE_MOVABLE not
highmem if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not set.  In online_pages,
it extracts pages from the previous zone before ZONE_MOVABLE.  Which is
logically inconsistent:

If HAVE_MEMBLOCK_NODE_MAP is turned off but HIGHMEM is on,
zone_movable_is_highmem() makes movable zone not highmem, but
online_pages() extracts pages from ZONE_HIGHMEM.

This inconsistency doesn't cause real problem currently, because all
architectures support online_pages also have HAVE_MEMBLOCK_NODE_MAP.
However, fixing it makes code clear, and also helps futher coding.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Zhang Zhen <zhangzhen@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the newer and more pleasant kstrtoull() to replace
simple_strtoull(), because simple_strtoull() is marked for obsoletion.
Signed-off-by: NZhang Zhen <zhenzhang.zhang@huawei.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Kmem page charging and uncharging is serialized by means of exclusive
access to the page.  Do not take the page_cgroup lock and don't set
pc->flags atomically.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Acked-by: NVladimir Davydov <vdavydov@parallels.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a write barrier between setting pc->mem_cgroup and
PageCgroupUsed, which was added to allow LRU operations to lookup the
memcg LRU list of a page without acquiring the page_cgroup lock.

But ever since commit 38c5d72f ("memcg: simplify LRU handling by new
rule"), pages are ensured to be off-LRU while charging, so nobody else
is changing LRU state while pc->mem_cgroup is being written, and there
are no read barriers anymore.

Remove the unnecessary write barrier.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Due to an old optimization to keep expensive res_counter changes at a
minimum, the root_mem_cgroup res_counter is never charged; there is no
limit at that level anyway, and any statistics can be generated on
demand by summing up the counters of all other cgroups.

However, with per-cpu charge caches, res_counter operations do not even
show up in profiles anymore, so this optimization is no longer
necessary.

Remove it to simplify the code.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When mem_cgroup_try_charge() returns -EINTR, it bypassed the charge to
the root memcg.  But move precharging does not catch this and treats
this case as if no charge had happened, thus leaking a charge against
root.  Because of an old optimization, the root memcg's res_counter is
not actually charged right now, but it's still an imbalance and
subsequent patches will charge the root memcg again.

Catch those bypasses to the root memcg and properly cancel them before
giving up the move.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The move precharge function does some baroque things: it tries raw
res_counter charging of the entire amount first, and then falls back to
a loop of one-by-one charges, with checks for pending signals and
cond_resched() batching.

Just use mem_cgroup_try_charge() without __GFP_WAIT for the first bulk
charge attempt.  In the one-by-one loop, remove the signal check (this
is already checked in try_charge), and simply call cond_resched() after
every charge - it's not that expensive.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For the page allocator, __GFP_NORETRY implies that no OOM should be
triggered, whereas memcg has an explicit parameter to disable OOM.

The only callsites that want OOM disabled are THP charges and charge
moving.  THP already uses __GFP_NORETRY and charge moving can use it as
well - one full reclaim cycle should be plenty.  Switch it over, then
remove the OOM parameter.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>