Constify `struct zs_pool' ->name.

[akpm@inux-foundation.org: constify zpool_create_pool()'s `type' arg also]
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: NDan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the return type of zpool_get_type const; the string belongs to the
zpool driver and should not be modified.  Remove the redundant type field
in the struct zpool; it is private to zpool.c and isn't needed since
->driver->type can be used directly.  Add comments indicating strings must
be null-terminated.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of using a fixed-length string for the zswap params, use charp.
This simplifies the code and uses less memory, as most zswap param strings
will be less than the current maximum length.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change the param_free_charp() function from static to exported.

It is used by zswap in the next patch ("zswap: use charp for zswap param
strings").
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On the next line entry variable will be re-initialized so no need to init
it with NULL.
Signed-off-by: NAlexey Klimov <alexey.klimov@linaro.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make is_partial_io()/valid_io_request()/page_zero_filled() return boolean,
since each function only uses either one or zero as its return value.
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Reviewed-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

`mem_used_max' is designed to store the max amount of memory zram consumed
to store the data.  However, it does not represent the actual
'overcommited' (max) value.  The existing code goes to -ENOMEM
overcommited case before it updates `->stats.max_used_pages', which hides
the reason we went to -ENOMEM in the first place -- we actually used more
memory than `->limit_pages':

        alloced_pages = zs_get_total_pages(meta->mem_pool);
        if (zram->limit_pages && alloced_pages > zram->limit_pages) {
                zs_free(meta->mem_pool, handle);
                ret = -ENOMEM;
                goto out;
        }

        update_used_max(zram, alloced_pages);

Which is misleading.  User will see -ENOMEM, check `->limit_pages', check
`->stats.max_used_pages', which will keep the value BEFORE zram passed
`->limit_pages', and see:
	`->stats.max_used_pages' < `->limit_pages'

Move update_used_max() before we do `->limit_pages' check, so that
user will see:
	`->stats.max_used_pages' > `->limit_pages'
should the overcommit and -ENOMEM happen.
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
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>

When the user supplies an unsupported compression algorithm, keep the
previously selected one (knowingly supported) or the default one (if the
compression algorithm hasn't been changed yet).

Note that previously this operation (i.e. setting an invalid algorithm)
would result in no algorithm being selected, which means that this
represents a small change in the default behaviour.

Minchan said:

For initializing zram, we need to set up 3 optional parameters in advance.

1. the number of compression streams
2. memory limitation
3. compression algorithm

Although user pass completely wrong value to set up for 1 and 2
parameters, it's okay because they have default value so zram will be
initialized with the default value (of course, when user passes a wrong
value via *echo*, sysfs returns -EINVAL so the user can notice it).

But 3 is not consistent with other optional parameters.  IOW, if the
user passes a wrong value to set up 3 parameter, zram's initialization
would fail unlike other optional parameters.

So this patch makes them consistent.
Signed-off-by: NLuis Henriques <luis.henriques@canonical.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

gcc version 5.2.1 20151010 (Debian 5.2.1-22)
$ size mm/memcontrol.o mm/memcontrol.o.before
   text    data     bss     dec     hex filename
  35535    7908      64   43507    a9f3 mm/memcontrol.o
  35762    7908      64   43734    aad6 mm/memcontrol.o.before

Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sync_file_range(2) is documented to issue writeback only for pages that
are not currently being written.  After all the system call has been
created for userspace to be able to issue background writeout and so
waiting for in-flight IO is undesirable there.  However commit
ee53a891 ("mm: do_sync_mapping_range integrity fix") switched
do_sync_mapping_range() and thus sync_file_range() to issue writeback in
WB_SYNC_ALL mode since do_sync_mapping_range() was used by other code
relying on WB_SYNC_ALL semantics.

These days do_sync_mapping_range() went away and we can switch
sync_file_range(2) back to issuing WB_SYNC_NONE writeback.  That should
help PostgreSQL avoid large latency spikes when flushing data in the
background.

Andres measured a 20% increase in transactions per second on an SSD disk.
Signed-off-by: NJan Kara <jack@suse.com>
Reported-by: NAndres Freund <andres@anarazel.de>
Tested-By: NAndres Freund <andres@anarazel.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The "vma" parameter to khugepaged_alloc_page() is unused.  It has to
remain unused or the drop read lock 'map_sem' optimisation introduce by
commit 8b164568 ("mm, THP: don't hold mmap_sem in khugepaged when
allocating THP") wouldn't be safe.  So let's remove it.
Signed-off-by: NAaron Tomlin <atomlin@redhat.com>
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>

There are many places which use mapping_gfp_mask to restrict a more
generic gfp mask which would be used for allocations which are not
directly related to the page cache but they are performed in the same
context.

Let's introduce a helper function which makes the restriction explicit and
easier to track.  This patch doesn't introduce any functional changes.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Someone has an 86 column display.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Andrew stated the following

	We have quite a history of remote parts of the kernel using
	weird/wrong/inexplicable combinations of __GFP_ flags.	I tend
	to think that this is because we didn't adequately explain the
	interface.

	And I don't think that gfp.h really improved much in this area as
	a result of this patchset.  Could you go through it some time and
	decide if we've adequately documented all this stuff?

This patches first moves some GFP flag combinations that are part of the MM
internals to mm/internal.h. The rest of the patch documents the __GFP_FOO
bits under various headings and then documents the flag combinations. It
will not help callers that are brain damaged but the clarity might motivate
some fixes and avoid future mistakes.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The primary purpose of watermarks is to ensure that reclaim can always
make forward progress in PF_MEMALLOC context (kswapd and direct reclaim).
These assume that order-0 allocations are all that is necessary for
forward progress.

High-order watermarks serve a different purpose.  Kswapd had no high-order
awareness before they were introduced
(https://lkml.kernel.org/r/413AA7B2.4000907@yahoo.com.au).  This was
particularly important when there were high-order atomic requests.  The
watermarks both gave kswapd awareness and made a reserve for those atomic
requests.

There are two important side-effects of this.  The most important is that
a non-atomic high-order request can fail even though free pages are
available and the order-0 watermarks are ok.  The second is that
high-order watermark checks are expensive as the free list counts up to
the requested order must be examined.

With the introduction of MIGRATE_HIGHATOMIC it is no longer necessary to
have high-order watermarks.  Kswapd and compaction still need high-order
awareness which is handled by checking that at least one suitable
high-order page is free.

With the patch applied, there was little difference in the allocation
failure rates as the atomic reserves are small relative to the number of
allocation attempts.  The expected impact is that there will never be an
allocation failure report that shows suitable pages on the free lists.

The one potential side-effect of this is that in a vanilla kernel, the
watermark checks may have kept a free page for an atomic allocation.  Now,
we are 100% relying on the HighAtomic reserves and an early allocation to
have allocated them.  If the first high-order atomic allocation is after
the system is already heavily fragmented then it'll fail.

[akpm@linux-foundation.org: simplify __zone_watermark_ok(), per Vlastimil]
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

High-order watermark checking exists for two reasons -- kswapd high-order
awareness and protection for high-order atomic requests.  Historically the
kernel depended on MIGRATE_RESERVE to preserve min_free_kbytes as
high-order free pages for as long as possible.  This patch introduces
MIGRATE_HIGHATOMIC that reserves pageblocks for high-order atomic
allocations on demand and avoids using those blocks for order-0
allocations.  This is more flexible and reliable than MIGRATE_RESERVE was.

A MIGRATE_HIGHORDER pageblock is created when an atomic high-order
allocation request steals a pageblock but limits the total number to 1% of
the zone.  Callers that speculatively abuse atomic allocations for
long-lived high-order allocations to access the reserve will quickly fail.
 Note that SLUB is currently not such an abuser as it reclaims at least
once.  It is possible that the pageblock stolen has few suitable
high-order pages and will need to steal again in the near future but there
would need to be strong justification to search all pageblocks for an
ideal candidate.

The pageblocks are unreserved if an allocation fails after a direct
reclaim attempt.

The watermark checks account for the reserved pageblocks when the
allocation request is not a high-order atomic allocation.

The reserved pageblocks can not be used for order-0 allocations.  This may
allow temporary wastage until a failed reclaim reassigns the pageblock.
This is deliberate as the intent of the reservation is to satisfy a
limited number of atomic high-order short-lived requests if the system
requires them.

The stutter benchmark was used to evaluate this but while it was running
there was a systemtap script that randomly allocated between 1 high-order
page and 12.5% of memory's worth of order-3 pages using GFP_ATOMIC.  This
is much larger than the potential reserve and it does not attempt to be
realistic.  It is intended to stress random high-order allocations from an
unknown source, show that there is a reduction in failures without
introducing an anomaly where atomic allocations are more reliable than
regular allocations.  The amount of memory reserved varied throughout the
workload as reserves were created and reclaimed under memory pressure.
The allocation failures once the workload warmed up were as follows;

4.2-rc5-vanilla		70%
4.2-rc5-atomic-reserve	56%

The failure rate was also measured while building multiple kernels.  The
failure rate was 14% but is 6% with this patch applied.

Overall, this is a small reduction but the reserves are small relative to
the number of allocation requests.  In early versions of the patch, the
failure rate reduced by a much larger amount but that required much larger
reserves and perversely made atomic allocations seem more reliable than
regular allocations.

[yalin.wang2010@gmail.com: fix redundant check and a memory leak]
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Nyalin wang <yalin.wang2010@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

MIGRATE_RESERVE preserves an old property of the buddy allocator that
existed prior to fragmentation avoidance -- min_free_kbytes worth of pages
tended to remain contiguous until the only alternative was to fail the
allocation.  At the time it was discovered that high-order atomic
allocations relied on this property so MIGRATE_RESERVE was introduced.  A
later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch
deletes MIGRATE_RESERVE and supporting code so it'll be easier to review.
Note that this patch in isolation may look like a false regression if
someone was bisecting high-order atomic allocation failures.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The zonelist cache (zlc) was introduced to skip over zones that were
recently known to be full.  This avoided expensive operations such as the
cpuset checks, watermark calculations and zone_reclaim.  The situation
today is different and the complexity of zlc is harder to justify.

1) The cpuset checks are no-ops unless a cpuset is active and in general
   are a lot cheaper.

2) zone_reclaim is now disabled by default and I suspect that was a large
   source of the cost that zlc wanted to avoid. When it is enabled, it's
   known to be a major source of stalling when nodes fill up and it's
   unwise to hit every other user with the overhead.

3) Watermark checks are expensive to calculate for high-order
   allocation requests. Later patches in this series will reduce the cost
   of the watermark checking.

4) The most important issue is that in the current implementation it
   is possible for a failed THP allocation to mark a zone full for order-0
   allocations and cause a fallback to remote nodes.

The last issue could be addressed with additional complexity but as the
benefit of zlc is questionable, it is better to remove it.  If stalls due
to zone_reclaim are ever reported then an alternative would be to
introduce deferring logic based on a timeout inside zone_reclaim itself
and leave the page allocator fast paths alone.

The impact on page-allocator microbenchmarks is negligible as they don't
hit the paths where the zlc comes into play.  Most page-reclaim related
workloads showed no noticeable difference as a result of the removal.

The impact was noticeable in a workload called "stutter".  One part uses a
lot of anonymous memory, a second measures mmap latency and a third copies
a large file.  In an ideal world the latency application would not notice
the mmap latency.  On a 2-node machine the results of this patch are

stutter
                             4.3.0-rc1             4.3.0-rc1
                              baseline              nozlc-v4
Min         mmap     20.9243 (  0.00%)     20.7716 (  0.73%)
1st-qrtle   mmap     22.0612 (  0.00%)     22.0680 ( -0.03%)
2nd-qrtle   mmap     22.3291 (  0.00%)     22.3809 ( -0.23%)
3rd-qrtle   mmap     25.2244 (  0.00%)     25.2396 ( -0.06%)
Max-90%     mmap     48.0995 (  0.00%)     28.3713 ( 41.02%)
Max-93%     mmap     52.5557 (  0.00%)     36.0170 ( 31.47%)
Max-95%     mmap     55.8173 (  0.00%)     47.3163 ( 15.23%)
Max-99%     mmap     67.3781 (  0.00%)     70.1140 ( -4.06%)
Max         mmap  24447.6375 (  0.00%)  12915.1356 ( 47.17%)
Mean        mmap     33.7883 (  0.00%)     27.7944 ( 17.74%)
Best99%Mean mmap     27.7825 (  0.00%)     25.2767 (  9.02%)
Best95%Mean mmap     26.3912 (  0.00%)     23.7994 (  9.82%)
Best90%Mean mmap     24.9886 (  0.00%)     23.2251 (  7.06%)
Best50%Mean mmap     22.0157 (  0.00%)     22.0261 ( -0.05%)
Best10%Mean mmap     21.6705 (  0.00%)     21.6083 (  0.29%)
Best5%Mean  mmap     21.5581 (  0.00%)     21.4611 (  0.45%)
Best1%Mean  mmap     21.3079 (  0.00%)     21.1631 (  0.68%)

Note that the maximum stall latency went from 24 seconds to 12 which is
still bad but an improvement.  The milage varies considerably 2-node
machine on an earlier test went from 494 seconds to 47 seconds and a
4-node machine that tested an earlier version of this patch went from a
worst case stall time of 6 seconds to 67ms.  The nature of the benchmark
is inherently unpredictable as it is hammering the system and the milage
will vary between machines.

There is a secondary impact with potentially more direct reclaim because
zones are now being considered instead of being skipped by zlc.  In this
particular test run it did not occur so will not be described.  However,
in at least one test the following was observed

1. Direct reclaim rates were higher. This was likely due to direct reclaim
  being entered instead of the zlc disabling a zone and busy looping.
  Busy looping may have the effect of allowing kswapd to make more
  progress and in some cases may be better overall. If this is found then
  the correct action is to put direct reclaimers to sleep on a waitqueue
  and allow kswapd make forward progress. Busy looping on the zlc is even
  worse than when the allocator used to blindly call congestion_wait().

2. There was higher swap activity as direct reclaim was active.

3. Direct reclaim efficiency was lower. This is related to 1 as more
  scanning activity also encountered more pages that could not be
  immediately reclaimed

In that case, the direct page scan and reclaim rates are noticeable but
it is not considered a problem for a few reasons

1. The test is primarily concerned with latency. The mmap attempts are also
   faulted which means there are THP allocation requests. The ZLC could
   cause zones to be disabled causing the process to busy loop instead
   of reclaiming.  This looks like elevated direct reclaim activity but
   it's the correct action to take based on what processes requested.

2. The test hammers reclaim and compaction heavily. The number of successful
   THP faults is highly variable but affects the reclaim stats. It's not a
   realistic or reasonable measure of page reclaim activity.

3. No other page-reclaim intensive workload that was tested showed a problem.

4. If a workload is identified that benefitted from the busy looping then it
   should be fixed by having direct reclaimers sleep on a wait queue until
   woken by kswapd instead of busy looping. We had this class of problem before
   when congestion_waits() with a fixed timeout was a brain damaged decision
   but happened to benefit some workloads.

If a workload is identified that relied on the zlc to busy loop then it
should be fixed correctly and have a direct reclaimer sleep on a waitqueue
until woken by kswapd.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep.  Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep.  The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake.  As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags.  This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

GFP_IOFS was intended to be shorthand for clearing two flags, not a set of
allocation flags.  There is only one user of this flag combination now and
there appears to be no reason why Lustre had to be protected from reclaim
stalls.  As none of the sites appear to be atomic, this patch simply
deletes GFP_IOFS and converts Lustre to using GFP_KERNEL, GFP_NOFS or
GFP_NOIO as appropriate.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch redefines which GFP bits are used for specifying mobility and
the order of the migrate types.  Once redefined it's possible to convert
GFP flags to a migrate type with a simple mask and shift.  The only
downside is that readers of OOM kill messages and allocation failures may
have been used to the existing values but scripts/gfp-translate will help.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a seqcounter that protects against spurious allocation failures
when a task is changing the allowed nodes in a cpuset.  There is no need
to check the seqcounter until a cpuset exists.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

File-backed pages that will be immediately written are balanced between
zones.  This heuristic tries to avoid having a single zone filled with
recently dirtied pages but the checks are unnecessarily expensive.  Move
consider_zone_balanced into the alloc_context instead of checking bitmaps
multiple times.  The patch also gives the parameter a more meaningful
name.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Overall, the intent of this series is to remove the zonelist cache which
was introduced to avoid high overhead in the page allocator.  Once this is
done, it is necessary to reduce the cost of watermark checks.

The series starts with minor micro-optimisations.

Next it notes that GFP flags that affect watermark checks are abused.
__GFP_WAIT historically identified callers that could not sleep and could
access reserves.  This was later abused to identify callers that simply
prefer to avoid sleeping and have other options.  A patch distinguishes
between atomic callers, high-priority callers and those that simply wish
to avoid sleep.

The zonelist cache has been around for a long time but it is of dubious
merit with a lot of complexity and some issues that are explained.  The
most important issue is that a failed THP allocation can cause a zone to
be treated as "full".  This potentially causes unnecessary stalls, reclaim
activity or remote fallbacks.  The issues could be fixed but it's not
worth it.  The series places a small number of other micro-optimisations
on top before examining GFP flags watermarks.

High-order watermarks enforcement can cause high-order allocations to fail
even though pages are free.  The watermark checks both protect high-order
atomic allocations and make kswapd aware of high-order pages but there is
a much better way that can be handled using migrate types.  This series
uses page grouping by mobility to reserve pageblocks for high-order
allocations with the size of the reservation depending on demand.  kswapd
awareness is maintained by examining the free lists.  By patch 12 in this
series, there are no high-order watermark checks while preserving the
properties that motivated the introduction of the watermark checks.

This patch (of 10):

No user of zone_watermark_ok_safe() specifies alloc_flags.  This patch
removes the unnecessary parameter.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NChristoph Lameter <cl@linux.com>
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>

Introduce is_sysrq_oom helper function indicating oom kill triggered
by sysrq to improve readability.

No functional changes.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Acked-by: NDavid Rientjes <rientjes@google.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>

Pull backlight updates from Lee Jones:
 "New Device Support
   - None

  New Functionality:
   - None

  Core Frameworks:
   - Reject legacy PWM request for device defined in DT

  Fix-ups:
   - Remove unnecessary MODULE_ALIAS(); adp8860_bl, adp8870_bl
   - Simplify code: pm8941-wled
   - Supply default-brightness logic; pm8941-wled

  Bug Fixes:
   - Clean up OF node; 88pm860x_bl
   - Ensure struct is zeroed; lp855x_bl"

* tag 'backlight-for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  backlight: pm8941-wled: Add default-brightness property
  backlight: pm8941-wled: Fix ptr_ret.cocci warnings
  backlight: pwm: Reject legacy PWM request for device defined in DT
  backlight: 88pm860x_bl: Add missing of_node_put
  backlight: adp8870: Remove unnecessary MODULE_ALIAS()
  backlight: adp8860: Remove unnecessary MODULE_ALIAS()
  backlight: lp855x: Make sure props struct is zeroed

Commit b158b69a ("mfd: rtsx: Simplify function return logic")
removed the use of the 'err' variable, but left the variable itself
around, resulting in gcc quite reasonably warning:

    drivers/mfd/rtsx_pcr.c: In function ‘rtsx_pci_set_pull_ctl’:
    drivers/mfd/rtsx_pcr.c:565:6: warning: unused variable ‘err’ [-Wunused-variable]
      int err;
          ^

Get rid of the unused variable, and avoid the new warning.

Cc: Javier Martinez Canillas <javier@osg.samsung.com>
Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull MFD updates from Lee Jones:
 "New Device Support:
   - Add support for 88pm860; 88pm80x
   - Add support for 24c08 EEPROM; at24
   - Add support for Broxton Whiskey Cove; intel*
   - Add support for RTS522A; rts5227
   - Add support for I2C devices; intel_quark_i2c_gpio

  New Functionality:
   - Add microphone support; arizona
   - Add general purpose switch support; arizona
   - Add fuel-gauge support; da9150-core
   - Add shutdown support; sec-core
   - Add charger support; tps65217
   - Add flexible serial communication unit support; atmel-flexcom
   - Add power button support; axp20x
   - Add led-flash support; rt5033

  Core Frameworks:
   - Supply a generic macro for defining Regmap IRQs
   - Rework ACPI child device matching

  Fix-ups:
   - Use Regmap to access registers; tps6105x
   - Use DEFINE_RES_IRQ_NAMED() macro; da9150
   - Re-arrange device registration order; intel_quark_i2c_gpio
   - Allow OF matching; cros_ec_i2c, atmel-hlcdc, hi6421-pmic, max8997, sm501
   - Handle deferred probe; twl6040
   - Improve accuracy of headphone detect; arizona
   - Unnecessary MODULE_ALIAS() removal; bcm590xx, rt5033
   - Remove unused code; htc-i2cpld, arizona, pcf50633-irq, sec-core
   - Simplify code; kempld, rts5209, da903x, lm3533, da9052, arizona
   - Remove #iffery; arizona
   - DT binding adaptions; many

  Bug Fixes:
   - Fix possible NULL pointer dereference; wm831x, tps6105x
   - Fix 64bit bug; intel_soc_pmic_bxtwc
   - Fix signedness issue; arizona"

* tag 'mfd-for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd: (73 commits)
  bindings: mfd: s2mps11: Add documentation for s2mps15 PMIC
  mfd: sec-core: Remove unused s2mpu02-rtc and s2mpu02-clk children
  extcon: arizona: Add extcon specific device tree binding document
  MAINTAINERS: Add binding docs for Cirrus Logic/Wolfson Arizona devices
  mfd: arizona: Remove bindings covered in new subsystem specific docs
  mfd: rt5033: Add RT5033 Flash led sub device
  mfd: lpss: Add Intel Broxton PCI IDs
  mfd: lpss: Add Broxton ACPI IDs
  mfd: arizona: Signedness bug in arizona_runtime_suspend()
  mfd: axp20x: Add a cell for the power button part of the, axp288 PMICs
  mfd: dt-bindings: Document pulled down WRSTBI pin on S2MPS1X
  mfd: sec-core: Disable buck voltage reset on watchdog falling edge
  mfd: sec-core: Dump PMIC revision to find out the HW
  mfd: arizona: Use correct type ID for device tree config
  mfd: arizona: Remove use of codec build config #ifdefs
  mfd: arizona: Simplify adding subdevices
  mfd: arizona: Downgrade type mismatch messages to dev_warn
  mfd: arizona: Factor out checking of jack detection state
  mfd: arizona: Factor out DCVDD isolation control
  mfd: Make TPS6105X select REGMAP_I2C
  ...

It turns out that we still have issues with the EFI memory map that ends
up polluting our kernel page tables with writable executable pages.

That will get sorted out, but in the meantime let's not make the scary
complaint about them be on by default.  The code is useful for
developers, but not ready for end user testing yet.
Acked-by: NBorislav Petkov <bp@alien8.de>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Merge tag 'platform-drivers-x86-v4.4-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver update from Darren Hart:
 "Various toshiba hotkey and keyboard related fixes and a new WMI
  driver.  Several intel_scu_ipc cleanups and a locking fix.  A
  spattering of small single fixes across various platforms.

  I was asked to pick up an OLPC cleanup as the driver appeared
  unmaintained and it seemed similar to what is maintained in
  platform/drivers/x86.  I have included the patch and an update to the
  MAINTAINERS file.

  toshiba_acpi:
   - Initialize hotkey_event_type variable
   - Remove unneeded u32 variables from *setup_keyboard
   - Add 0x prefix to available_kbd_modes_show function
   - Change default Hotkey enabling value
   - Unify hotkey enabling functions

  toshiba-wmi:
   - Toshiba WMI Hotkey Driver

  intel_scu_ipc:
   - Protect dev member assignment on ->remove()
   - Switch to use module_pci_driver() macro
   - Convert to use struct device *
   - Propagate pointer to struct intel_scu_ipc_dev
   - Fix error path by turning to devm_* / pcim_*

  acer-wmi:
   - remove threeg and interface sysfs interfaces

  OLPC:
   - Use %*ph specifier instead of passing direct values

  MAINTAINERS:
   - Add drivers/platform/olpc to drivers/platform/x86

  sony-laptop:
   - Fix handling sony_nc_hotkeys_decode result

  intel_mid_powerbtn:
   - Remove misuse of IRQF_NO_SUSPEND flag

  compal-laptop:
   - Add charge control limit

  asus-wmi:
   - restore kbd led level after resume"

* tag 'platform-drivers-x86-v4.4-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  toshiba_acpi: Initialize hotkey_event_type variable
  intel_scu_ipc: Protect dev member assignment on ->remove()
  intel_scu_ipc: Switch to use module_pci_driver() macro
  intel_scu_ipc: Convert to use struct device *
  intel_scu_ipc: Propagate pointer to struct intel_scu_ipc_dev
  intel_scu_ipc: Fix error path by turning to devm_* / pcim_*
  acer-wmi: remove threeg and interface sysfs interfaces
  OLPC: Use %*ph specifier instead of passing direct values
  MAINTAINERS: Add drivers/platform/olpc to drivers/platform/x86
  platform/x86: Toshiba WMI Hotkey Driver
  sony-laptop: Fix handling sony_nc_hotkeys_decode result
  intel_mid_powerbtn: Remove misuse of IRQF_NO_SUSPEND flag
  compal-laptop: Add charge control limit
  asus-wmi: restore kbd led level after resume
  toshiba_acpi: Remove unneeded u32 variables from *setup_keyboard
  toshiba_acpi: Add 0x prefix to available_kbd_modes_show function
  toshiba_acpi: Change default Hotkey enabling value
  toshiba_acpi: Unify hotkey enabling functions

Pull powerpc updates from Michael Ellerman:

 - Kconfig: remove BE-only platforms from LE kernel build from Boqun
   Feng
 - Refresh ps3_defconfig from Geoff Levand
 - Emit GNU & SysV hashes for the vdso from Michael Ellerman
 - Define an enum for the bolted SLB indexes from Anshuman Khandual
 - Use a local to avoid multiple calls to get_slb_shadow() from Michael
   Ellerman
 - Add gettimeofday() benchmark from Michael Neuling
 - Avoid link stack corruption in __get_datapage() from Michael Neuling
 - Add virt_to_pfn and use this instead of opencoding from Aneesh Kumar
   K.V
 - Add ppc64le_defconfig from Michael Ellerman
 - pseries: extract of_helpers module from Andy Shevchenko
 - Correct string length in pseries_of_derive_parent() from Nathan
   Fontenot
 - Free the MSI bitmap if it was slab allocated from Denis Kirjanov
 - Shorten irq_chip name for the SIU from Christophe Leroy
 - Wait 1s for secondaries to enter OPAL during kexec from Samuel
   Mendoza-Jonas
 - Fix _ALIGN_* errors due to type difference, from Aneesh Kumar K.V
 - powerpc/pseries/hvcserver: don't memset pi_buff if it is null from
   Colin Ian King
 - Disable hugepd for 64K page size, from Aneesh Kumar K.V
 - Differentiate between hugetlb and THP during page walk from Aneesh
   Kumar K.V
 - Make PCI non-optional for pseries from Michael Ellerman
 - Individual System V IPC system calls from Sam bobroff
 - Add selftest of unmuxed IPC calls from Michael Ellerman
 - discard .exit.data at runtime from Stephen Rothwell
 - Delete old orphaned PrPMC 280/2800 DTS and boot file, from Paul
   Gortmaker
 - Use of_get_next_parent to simplify code from Christophe Jaillet
 - Paginate some xmon output from Sam bobroff
 - Add some more elements to the xmon PACA dump from Michael Ellerman
 - Allow the tm-syscall selftest to build with old headers from Michael
   Ellerman
 - Run EBB selftests only on POWER8 from Denis Kirjanov
 - Drop CONFIG_TUNE_CELL in favour of CONFIG_CELL_CPU from Michael
   Ellerman
 - Avoid reference to potentially freed memory in prom.c from Christophe
   Jaillet
 - Quieten boot wrapper output with run_cmd from Geoff Levand
 - EEH fixes and cleanups from Gavin Shan
 - Fix recursive fenced PHB on Broadcom shiner adapter from Gavin Shan
 - Use of_get_next_parent() in of_get_ibm_chip_id() from Michael
   Ellerman
 - Fix section mismatch warning in msi_bitmap_alloc() from Denis
   Kirjanov
 - Fix ps3-lpm white space from Rudhresh Kumar J
 - Fix ps3-vuart null dereference from Colin King
 - nvram: Add missing kfree in error path from Christophe Jaillet
 - nvram: Fix function name in some errors messages, from Christophe
   Jaillet
 - drivers/macintosh: adb: fix misleading Kconfig help text from Aaro
   Koskinen
 - agp/uninorth: fix a memleak in create_gatt_table from Denis Kirjanov
 - cxl: Free virtual PHB when removing from Andrew Donnellan
 - scripts/kconfig/Makefile: Allow KBUILD_DEFCONFIG to be a target from
   Michael Ellerman
 - scripts/kconfig/Makefile: Fix KBUILD_DEFCONFIG check when building
   with O= from Michael Ellerman
 - Freescale updates from Scott: Highlights include 64-bit book3e
   kexec/kdump support, a rework of the qoriq clock driver, device tree
   changes including qoriq fman nodes, support for a new 85xx board, and
   some fixes.
 - MPC5xxx updates from Anatolij: Highlights include a driver for
   MPC512x LocalPlus Bus FIFO with its device tree binding
   documentation, mpc512x device tree updates and some minor fixes.

* tag 'powerpc-4.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (106 commits)
  powerpc/msi: Fix section mismatch warning in msi_bitmap_alloc()
  powerpc/prom: Use of_get_next_parent() in of_get_ibm_chip_id()
  powerpc/pseries: Correct string length in pseries_of_derive_parent()
  powerpc/e6500: hw tablewalk: make sure we invalidate and write to the same tlb entry
  powerpc/mpc85xx: Add FSL QorIQ DPAA FMan support to the SoC device tree(s)
  powerpc/mpc85xx: Create dts components for the FSL QorIQ DPAA FMan
  powerpc/fsl: Add #clock-cells and clockgen label to clockgen nodes
  powerpc: handle error case in cpm_muram_alloc()
  powerpc: mpic: use IRQCHIP_SKIP_SET_WAKE instead of redundant mpic_irq_set_wake
  powerpc/book3e-64: Enable kexec
  powerpc/book3e-64/kexec: Set "r4 = 0" when entering spinloop
  powerpc/booke: Only use VIRT_PHYS_OFFSET on booke32
  powerpc/book3e-64/kexec: Enable SMP release
  powerpc/book3e-64/kexec: create an identity TLB mapping
  powerpc/book3e-64: Don't limit paca to 256 MiB
  powerpc/book3e/kdump: Enable crash_kexec_wait_realmode
  powerpc/book3e: support CONFIG_RELOCATABLE
  powerpc/booke64: Fix args to copy_and_flush
  powerpc/book3e-64: rename interrupt_end_book3e with __end_interrupts
  powerpc/e6500: kexec: Handle hardware threads
  ...

Merge patch-bomb from Andrew Morton:

 - inotify tweaks

 - some ocfs2 updates (many more are awaiting review)

 - various misc bits

 - kernel/watchdog.c updates

 - Some of mm.  I have a huge number of MM patches this time and quite a
   lot of it is quite difficult and much will be held over to next time.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (162 commits)
  selftests: vm: add tests for lock on fault
  mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage
  mm: introduce VM_LOCKONFAULT
  mm: mlock: add new mlock system call
  mm: mlock: refactor mlock, munlock, and munlockall code
  kasan: always taint kernel on report
  mm, slub, kasan: enable user tracking by default with KASAN=y
  kasan: use IS_ALIGNED in memory_is_poisoned_8()
  kasan: Fix a type conversion error
  lib: test_kasan: add some testcases
  kasan: update reference to kasan prototype repo
  kasan: move KASAN_SANITIZE in arch/x86/boot/Makefile
  kasan: various fixes in documentation
  kasan: update log messages
  kasan: accurately determine the type of the bad access
  kasan: update reported bug types for kernel memory accesses
  kasan: update reported bug types for not user nor kernel memory accesses
  mm/kasan: prevent deadlock in kasan reporting
  mm/kasan: don't use kasan shadow pointer in generic functions
  mm/kasan: MODULE_VADDR is not available on all archs
  ...

This fixes a bug from commit f3f86e33 ("vfs: Fix pathological
performance case for __alloc_fd()").

v2: refactor to share fd bitmap copying code
Signed-off-by: NEric Biggers <ebiggers3@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Test the mmap() flag, and the mlockall() flag.  These tests ensure that
pages are not faulted in until they are accessed, that the pages are
unevictable once faulted in, and that VMA splitting and merging works with
the new VM flag.  The second test ensures that mlock limits are respected.
 Note that the limit test needs to be run a normal user.

Also add tests to use the new mlock2 family of system calls.

[treding@nvidia.com: : Fix mlock2-tests for 32-bit architectures]
[treding@nvidia.com: ensure the mlock2 syscall number can be found]
[treding@nvidia.com: use the right arguments for main()]
Signed-off-by: NEric B Munson <emunson@akamai.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The previous patch introduced a flag that specified pages in a VMA should
be placed on the unevictable LRU, but they should not be made present when
the area is created.  This patch adds the ability to set this state via
the new mlock system calls.

We add MLOCK_ONFAULT for mlock2 and MCL_ONFAULT for mlockall.
MLOCK_ONFAULT will set the VM_LOCKONFAULT modifier for VM_LOCKED.
MCL_ONFAULT should be used as a modifier to the two other mlockall flags.
When used with MCL_CURRENT, all current mappings will be marked with
VM_LOCKED | VM_LOCKONFAULT.  When used with MCL_FUTURE, the mm->def_flags
will be marked with VM_LOCKED | VM_LOCKONFAULT.  When used with both
MCL_CURRENT and MCL_FUTURE, all current mappings and mm->def_flags will be
marked with VM_LOCKED | VM_LOCKONFAULT.

Prior to this patch, mlockall() will unconditionally clear the
mm->def_flags any time it is called without MCL_FUTURE.  This behavior is
maintained after adding MCL_ONFAULT.  If a call to mlockall(MCL_FUTURE) is
followed by mlockall(MCL_CURRENT), the mm->def_flags will be cleared and
new VMAs will be unlocked.  This remains true with or without MCL_ONFAULT
in either mlockall() invocation.

munlock() will unconditionally clear both vma flags.  munlockall()
unconditionally clears for VMA flags on all VMAs and in the mm->def_flags
field.
Signed-off-by: NEric B Munson <emunson@akamai.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The cost of faulting in all memory to be locked can be very high when
working with large mappings.  If only portions of the mapping will be used
this can incur a high penalty for locking.

For the example of a large file, this is the usage pattern for a large
statical language model (probably applies to other statical or graphical
models as well).  For the security example, any application transacting in
data that cannot be swapped out (credit card data, medical records, etc).

This patch introduces the ability to request that pages are not
pre-faulted, but are placed on the unevictable LRU when they are finally
faulted in.  The VM_LOCKONFAULT flag will be used together with VM_LOCKED
and has no effect when set without VM_LOCKED.  Setting the VM_LOCKONFAULT
flag for a VMA will cause pages faulted into that VMA to be added to the
unevictable LRU when they are faulted or if they are already present, but
will not cause any missing pages to be faulted in.

Exposing this new lock state means that we cannot overload the meaning of
the FOLL_POPULATE flag any longer.  Prior to this patch it was used to
mean that the VMA for a fault was locked.  This means we need the new
FOLL_MLOCK flag to communicate the locked state of a VMA.  FOLL_POPULATE
will now only control if the VMA should be populated and in the case of
VM_LOCKONFAULT, it will not be set.
Signed-off-by: NEric B Munson <emunson@akamai.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With the refactored mlock code, introduce a new system call for mlock.
The new call will allow the user to specify what lock states are being
added.  mlock2 is trivial at the moment, but a follow on patch will add a
new mlock state making it useful.
Signed-off-by: NEric B Munson <emunson@akamai.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mlock() allows a user to control page out of program memory, but this
comes at the cost of faulting in the entire mapping when it is allocated.
For large mappings where the entire area is not necessary this is not
ideal.  Instead of forcing all locked pages to be present when they are
allocated, this set creates a middle ground.  Pages are marked to be
placed on the unevictable LRU (locked) when they are first used, but they
are not faulted in by the mlock call.

This series introduces a new mlock() system call that takes a flags
argument along with the start address and size.  This flags argument gives
the caller the ability to request memory be locked in the traditional way,
or to be locked after the page is faulted in.  A new MCL flag is added to
mirror the lock on fault behavior from mlock() in mlockall().

There are two main use cases that this set covers.  The first is the
security focussed mlock case.  A buffer is needed that cannot be written
to swap.  The maximum size is known, but on average the memory used is
significantly less than this maximum.  With lock on fault, the buffer is
guaranteed to never be paged out without consuming the maximum size every
time such a buffer is created.

The second use case is focussed on performance.  Portions of a large file
are needed and we want to keep the used portions in memory once accessed.
This is the case for large graphical models where the path through the
graph is not known until run time.  The entire graph is unlikely to be
used in a given invocation, but once a node has been used it needs to stay
resident for further processing.  Given these constraints we have a number
of options.  We can potentially waste a large amount of memory by mlocking
the entire region (this can also cause a significant stall at startup as
the entire file is read in).  We can mlock every page as we access them
without tracking if the page is already resident but this introduces large
overhead for each access.  The third option is mapping the entire region
with PROT_NONE and using a signal handler for SIGSEGV to
mprotect(PROT_READ) and mlock() the needed page.  Doing this page at a
time adds a significant performance penalty.  Batching can be used to
mitigate this overhead, but in order to safely avoid trying to mprotect
pages outside of the mapping, the boundaries of each mapping to be used in
this way must be tracked and available to the signal handler.  This is
precisely what the mm system in the kernel should already be doing.

For mlock(MLOCK_ONFAULT) the user is charged against RLIMIT_MEMLOCK as if
mlock(MLOCK_LOCKED) or mmap(MAP_LOCKED) was used, so when the VMA is
created not when the pages are faulted in.  For mlockall(MCL_ONFAULT) the
user is charged as if MCL_FUTURE was used.  This decision was made to keep
the accounting checks out of the page fault path.

To illustrate the benefit of this set I wrote a test program that mmaps a
5 GB file filled with random data and then makes 15,000,000 accesses to
random addresses in that mapping.  The test program was run 20 times for
each setup.  Results are reported for two program portions, setup and
execution.  The setup phase is calling mmap and optionally mlock on the
entire region.  For most experiments this is trivial, but it highlights
the cost of faulting in the entire region.  Results are averages across
the 20 runs in milliseconds.

mmap with mlock(MLOCK_LOCKED) on entire range:
Setup avg:      8228.666
Processing avg: 8274.257

mmap with mlock(MLOCK_LOCKED) before each access:
Setup avg:      0.113
Processing avg: 90993.552

mmap with PROT_NONE and signal handler and batch size of 1 page:
With the default value in max_map_count, this gets ENOMEM as I attempt
to change the permissions, after upping the sysctl significantly I get:
Setup avg:      0.058
Processing avg: 69488.073
mmap with PROT_NONE and signal handler and batch size of 8 pages:
Setup avg:      0.068
Processing avg: 38204.116

mmap with PROT_NONE and signal handler and batch size of 16 pages:
Setup avg:      0.044
Processing avg: 29671.180

mmap with mlock(MLOCK_ONFAULT) on entire range:
Setup avg:      0.189
Processing avg: 17904.899

The signal handler in the batch cases faulted in memory in two steps to
avoid having to know the start and end of the faulting mapping.  The first
step covers the page that caused the fault as we know that it will be
possible to lock.  The second step speculatively tries to mlock and
mprotect the batch size - 1 pages that follow.  There may be a clever way
to avoid this without having the program track each mapping to be covered
by this handeler in a globally accessible structure, but I could not find
it.  It should be noted that with a large enough batch size this two step
fault handler can still cause the program to crash if it reaches far
beyond the end of the mapping.

These results show that if the developer knows that a majority of the
mapping will be used, it is better to try and fault it in at once,
otherwise mlock(MLOCK_ONFAULT) is significantly faster.

The performance cost of these patches are minimal on the two benchmarks I
have tested (stream and kernbench).  The following are the average values
across 20 runs of stream and 10 runs of kernbench after a warmup run whose
results were discarded.

Avg throughput in MB/s from stream using 1000000 element arrays
Test     4.2-rc1      4.2-rc1+lock-on-fault
Copy:    10,566.5     10,421
Scale:   10,685       10,503.5
Add:     12,044.1     11,814.2
Triad:   12,064.8     11,846.3

Kernbench optimal load
                 4.2-rc1  4.2-rc1+lock-on-fault
Elapsed Time     78.453   78.991
User Time        64.2395  65.2355
System Time      9.7335   9.7085
Context Switches 22211.5  22412.1
Sleeps           14965.3  14956.1

This patch (of 6):

Extending the mlock system call is very difficult because it currently
does not take a flags argument.  A later patch in this set will extend
mlock to support a middle ground between pages that are locked and faulted
in immediately and unlocked pages.  To pave the way for the new system
call, the code needs some reorganization so that all the actual entry
point handles is checking input and translating to VMA flags.
Signed-off-by: NEric B Munson <emunson@akamai.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently we already taint the kernel in some cases.  E.g.  if we hit some
bug in slub memory we call object_err() which will taint the kernel with
TAINT_BAD_PAGE flag.  But for other kind of bugs kernel left untainted.

Always taint with TAINT_BAD_PAGE if kasan found some bug.  This is useful
for automated testing.
Signed-off-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>