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  1. 29 7月, 2020 1 次提交
  3. 27 12月, 2019 4 次提交
  5. 06 10月, 2018 2 次提交
  7. 29 6月, 2018 1 次提交
    • S
      Revert mm/vmstat.c: fix vmstat_update() preemption BUG · 28557cc1
      由 Sebastian Andrzej Siewior 提交于 
      Revert commit c7f26ccf ("mm/vmstat.c: fix vmstat_update() preemption
BUG").  Steven saw a "using smp_processor_id() in preemptible" message
and added a preempt_disable() section around it to keep it quiet.  This
is not the right thing to do it does not fix the real problem.

vmstat_update() is invoked by a kworker on a specific CPU.  This worker
it bound to this CPU.  The name of the worker was "kworker/1:1" so it
should have been a worker which was bound to CPU1.  A worker which can
run on any CPU would have a `u' before the first digit.

smp_processor_id() can be used in a preempt-enabled region as long as
the task is bound to a single CPU which is the case here.  If it could
run on an arbitrary CPU then this is the problem we have an should seek
to resolve.

Not only this smp_processor_id() must not be migrated to another CPU but
also refresh_cpu_vm_stats() which might access wrong per-CPU variables.
Not to mention that other code relies on the fact that such a worker
runs on one specific CPU only.

Therefore revert that commit and we should look instead what broke the
affinity mask of the kworker.

Link: http://lkml.kernel.org/r/20180504104451.20278-1-bigeasy@linutronix.deSigned-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven J. Hill <steven.hill@cavium.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      28557cc1
  9. 16 5月, 2018 1 次提交
  11. 12 5月, 2018 1 次提交
  13. 12 4月, 2018 1 次提交
  15. 29 3月, 2018 1 次提交
  17. 16 11月, 2017 2 次提交
  19. 09 9月, 2017 3 次提交
    • K
      mm: consider the number in local CPUs when reading NUMA stats · 63803222
      由 Kemi Wang 提交于 
      To avoid deviation, the per cpu number of NUMA stats in
vm_numa_stat_diff[] is included when a user *reads* the NUMA stats.

Since NUMA stats does not be read by users frequently, and kernel does not
need it to make a decision, it will not be a problem to make the readers
more expensive.

Link: http://lkml.kernel.org/r/1503568801-21305-4-git-send-email-kemi.wang@intel.comSigned-off-by: NKemi Wang <kemi.wang@intel.com>
Reported-by: NJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      63803222
    • K
      mm: update NUMA counter threshold size · 1d90ca89
      由 Kemi Wang 提交于 
      There is significant overhead in cache bouncing caused by zone counters
(NUMA associated counters) update in parallel in multi-threaded page
allocation (suggested by Dave Hansen).

This patch updates NUMA counter threshold to a fixed size of MAX_U16 - 2,
as a small threshold greatly increases the update frequency of the global
counter from local per cpu counter(suggested by Ying Huang).

The rationality is that these statistics counters don't affect the
kernel's decision, unlike other VM counters, so it's not a problem to use
a large threshold.

With this patchset, we see 31.3% drop of CPU cycles(537-->369) for per
single page allocation and reclaim on Jesper's page_bench03 benchmark.

Benchmark provided by Jesper D Brouer(increase loop times to 10000000):
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/
bench

 Threshold   CPU cycles    Throughput(88 threads)
     32          799         241760478
     64          640         301628829
     125         537         358906028 <==> system by default (base)
     256         468         412397590
     512         428         450550704
     4096        399         482520943
     20000       394         489009617
     30000       395         488017817
     65533       369(-31.3%) 521661345(+45.3%) <==> with this patchset
     N/A         342(-36.3%) 562900157(+56.8%) <==> disable zone_statistics

Link: http://lkml.kernel.org/r/1503568801-21305-3-git-send-email-kemi.wang@intel.comSigned-off-by: NKemi Wang <kemi.wang@intel.com>
Reported-by: NJesper Dangaard Brouer <brouer@redhat.com>
Suggested-by: NDave Hansen <dave.hansen@intel.com>
Suggested-by: NYing Huang <ying.huang@intel.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1d90ca89
    • K
      mm: change the call sites of numa statistics items · 3a321d2a
      由 Kemi Wang 提交于 
      Patch series "Separate NUMA statistics from zone statistics", v2.

Each page allocation updates a set of per-zone statistics with a call to
zone_statistics().  As discussed in 2017 MM summit, these are a
substantial source of overhead in the page allocator and are very rarely
consumed.  This significant overhead in cache bouncing caused by zone
counters (NUMA associated counters) update in parallel in multi-threaded
page allocation (pointed out by Dave Hansen).

A link to the MM summit slides:
  http://people.netfilter.org/hawk/presentations/MM-summit2017/MM-summit2017-JesperBrouer.pdf

To mitigate this overhead, this patchset separates NUMA statistics from
zone statistics framework, and update NUMA counter threshold to a fixed
size of MAX_U16 - 2, as a small threshold greatly increases the update
frequency of the global counter from local per cpu counter (suggested by
Ying Huang).  The rationality is that these statistics counters don't
need to be read often, unlike other VM counters, so it's not a problem
to use a large threshold and make readers more expensive.

With this patchset, we see 31.3% drop of CPU cycles(537-->369, see
below) for per single page allocation and reclaim on Jesper's
page_bench03 benchmark.  Meanwhile, this patchset keeps the same style
of virtual memory statistics with little end-user-visible effects (only
move the numa stats to show behind zone page stats, see the first patch
for details).

I did an experiment of single page allocation and reclaim concurrently
using Jesper's page_bench03 benchmark on a 2-Socket Broadwell-based
server (88 processors with 126G memory) with different size of threshold
of pcp counter.

Benchmark provided by Jesper D Brouer(increase loop times to 10000000):
  https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench

   Threshold   CPU cycles    Throughput(88 threads)
      32        799         241760478
      64        640         301628829
      125       537         358906028 <==> system by default
      256       468         412397590
      512       428         450550704
      4096      399         482520943
      20000     394         489009617
      30000     395         488017817
      65533     369(-31.3%) 521661345(+45.3%) <==> with this patchset
      N/A       342(-36.3%) 562900157(+56.8%) <==> disable zone_statistics

This patch (of 3):

In this patch, NUMA statistics is separated from zone statistics
framework, all the call sites of NUMA stats are changed to use
numa-stats-specific functions, it does not have any functionality change
except that the number of NUMA stats is shown behind zone page stats
when users *read* the zone info.

E.g. cat /proc/zoneinfo
    ***Base***                           ***With this patch***
nr_free_pages 3976                         nr_free_pages 3976
nr_zone_inactive_anon 0                    nr_zone_inactive_anon 0
nr_zone_active_anon 0                      nr_zone_active_anon 0
nr_zone_inactive_file 0                    nr_zone_inactive_file 0
nr_zone_active_file 0                      nr_zone_active_file 0
nr_zone_unevictable 0                      nr_zone_unevictable 0
nr_zone_write_pending 0                    nr_zone_write_pending 0
nr_mlock     0                             nr_mlock     0
nr_page_table_pages 0                      nr_page_table_pages 0
nr_kernel_stack 0                          nr_kernel_stack 0
nr_bounce    0                             nr_bounce    0
nr_zspages   0                             nr_zspages   0
numa_hit 0                                *nr_free_cma  0*
numa_miss 0                                numa_hit     0
numa_foreign 0                             numa_miss    0
numa_interleave 0                          numa_foreign 0
numa_local   0                             numa_interleave 0
numa_other   0                             numa_local   0
*nr_free_cma 0*                            numa_other 0
    ...                                        ...
vm stats threshold: 10                     vm stats threshold: 10
    ...                                        ...

The next patch updates the numa stats counter size and threshold.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1503568801-21305-2-git-send-email-kemi.wang@intel.comSigned-off-by: NKemi Wang <kemi.wang@intel.com>
Reported-by: NJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.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>
      3a321d2a
  21. 07 9月, 2017 6 次提交
    • H
      mm, swap: add swap readahead hit statistics · cbc65df2
      由 Huang Ying 提交于 
      Patch series "mm, swap: VMA based swap readahead", v4.

The swap readahead is an important mechanism to reduce the swap in
latency.  Although pure sequential memory access pattern isn't very
popular for anonymous memory, the space locality is still considered
valid.

In the original swap readahead implementation, the consecutive blocks in
swap device are readahead based on the global space locality estimation.
But the consecutive blocks in swap device just reflect the order of page
reclaiming, don't necessarily reflect the access pattern in virtual
memory space.  And the different tasks in the system may have different
access patterns, which makes the global space locality estimation
incorrect.

In this patchset, when page fault occurs, the virtual pages near the
fault address will be readahead instead of the swap slots near the fault
swap slot in swap device.  This avoid to readahead the unrelated swap
slots.  At the same time, the swap readahead is changed to work on
per-VMA from globally.  So that the different access patterns of the
different VMAs could be distinguished, and the different readahead
policy could be applied accordingly.  The original core readahead
detection and scaling algorithm is reused, because it is an effect
algorithm to detect the space locality.

In addition to the swap readahead changes, some new sysfs interface is
added to show the efficiency of the readahead algorithm and some other
swap statistics.

This new implementation will incur more small random read, on SSD, the
improved correctness of estimation and readahead target should beat the
potential increased overhead, this is also illustrated in the test
results below.  But on HDD, the overhead may beat the benefit, so the
original implementation will be used by default.

The test and result is as follow,

Common test condition
=====================

Test Machine: Xeon E5 v3 (2 sockets, 72 threads, 32G RAM)
Swap device: NVMe disk

Micro-benchmark with combined access pattern
============================================

vm-scalability, sequential swap test case, 4 processes to eat 50G
virtual memory space, repeat the sequential memory writing until 300
seconds.  The first round writing will trigger swap out, the following
rounds will trigger sequential swap in and out.

At the same time, run vm-scalability random swap test case in
background, 8 processes to eat 30G virtual memory space, repeat the
random memory write until 300 seconds.  This will trigger random swap-in
in the background.

This is a combined workload with sequential and random memory accessing
at the same time.  The result (for sequential workload) is as follow,

			Base		Optimized
			----		---------
throughput		345413 KB/s	414029 KB/s (+19.9%)
latency.average		97.14 us	61.06 us (-37.1%)
latency.50th		2 us		1 us
latency.60th		2 us		1 us
latency.70th		98 us		2 us
latency.80th		160 us		2 us
latency.90th		260 us		217 us
latency.95th		346 us		369 us
latency.99th		1.34 ms		1.09 ms
ra_hit%			52.69%		99.98%

The original swap readahead algorithm is confused by the background
random access workload, so readahead hit rate is lower.  The VMA-base
readahead algorithm works much better.

Linpack
=======

The test memory size is bigger than RAM to trigger swapping.

			Base		Optimized
			----		---------
elapsed_time		393.49 s	329.88 s (-16.2%)
ra_hit%			86.21%		98.82%

The score of base and optimized kernel hasn't visible changes.  But the
elapsed time reduced and readahead hit rate improved, so the optimized
kernel runs better for startup and tear down stages.  And the absolute
value of readahead hit rate is high, shows that the space locality is
still valid in some practical workloads.

This patch (of 5):

The statistics for total readahead pages and total readahead hits are
recorded and exported via the following sysfs interface.

/sys/kernel/mm/swap/ra_hits
/sys/kernel/mm/swap/ra_total

With them, the efficiency of the swap readahead could be measured, so
that the swap readahead algorithm and parameters could be tuned
accordingly.

[akpm@linux-foundation.org: don't display swap stats if CONFIG_SWAP=n]
Link: http://lkml.kernel.org/r/20170807054038.1843-2-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.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>
      cbc65df2
    • S
      mm/vmstat.c: fix wrong comment · f113e641
      由 SeongJae Park 提交于 
      Comment for pagetypeinfo_showblockcount() is mistakenly duplicated from
pagetypeinfo_show_free()'s comment.  This commit fixes it.

Link: http://lkml.kernel.org/r/20170809185816.11244-1-sj38.park@gmail.com
Fixes: 467c996c ("Print out statistics in relation to fragmentation avoidance to /proc/pagetypeinfo")
Signed-off-by: NSeongJae Park <sj38.park@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f113e641
    • W
      mm/vmstat: fix divide error at __fragmentation_index · 88d6ac40
      由 Wen Yang 提交于 
      When order is -1 or too big, *1UL << order* will be 0, which will cause
a divide error.  Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the patch
can make it more robust.

Should prevent reoccurrences of
https://bugzilla.kernel.org/show_bug.cgi?id=196555

Link: http://lkml.kernel.org/r/1501751520-2598-1-git-send-email-wen.yang99@zte.com.cnSigned-off-by: NWen Yang <wen.yang99@zte.com.cn>
Reviewed-by: NJiang Biao <jiang.biao2@zte.com.cn>
Suggested-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      88d6ac40
    • M
      mm: rename global_page_state to global_zone_page_state · c41f012a
      由 Michal Hocko 提交于 
      global_page_state is error prone as a recent bug report pointed out [1].
It only returns proper values for zone based counters as the enum it
gets suggests.  We already have global_node_page_state so let's rename
global_page_state to global_zone_page_state to be more explicit here.
All existing users seems to be correct:

$ git grep "global_page_state(NR_" | sed 's@.*(\(NR_[A-Z_]*\)).*@\1@' | sort | uniq -c
      2 NR_BOUNCE
      2 NR_FREE_CMA_PAGES
     11 NR_FREE_PAGES
      1 NR_KERNEL_STACK_KB
      1 NR_MLOCK
      2 NR_PAGETABLE

This patch shouldn't introduce any functional change.

[1] http://lkml.kernel.org/r/201707260628.v6Q6SmaS030814@www262.sakura.ne.jp

Link: http://lkml.kernel.org/r/20170801134256.5400-2-hannes@cmpxchg.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c41f012a
    • H
      mm, THP, swap: add THP swapping out fallback counting · fe490cc0
      由 Huang Ying 提交于 
      When swapping out THP (Transparent Huge Page), instead of swapping out
the THP as a whole, sometimes we have to fallback to split the THP into
normal pages before swapping, because no free swap clusters are
available, or cgroup limit is exceeded, etc.  To count the number of the
fallback, a new VM event THP_SWPOUT_FALLBACK is added, and counted when
we fallback to split the THP.

Link: http://lkml.kernel.org/r/20170724051840.2309-13-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c]
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fe490cc0
    • H
      mm: test code to write THP to swap device as a whole · 225311a4
      由 Huang Ying 提交于 
      To support delay splitting THP (Transparent Huge Page) after swapped
out, we need to enhance swap writing code to support to write a THP as a
whole.  This will improve swap write IO performance.

As Ming Lei <ming.lei@redhat.com> pointed out, this should be based on
multipage bvec support, which hasn't been merged yet.  So this patch is
only for testing the functionality of the other patches in the series.
And will be reimplemented after multipage bvec support is merged.

Link: http://lkml.kernel.org/r/20170724051840.2309-7-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c]
Cc: Shaohua Li <shli@kernel.org>
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      225311a4
  23. 11 7月, 2017 1 次提交
  25. 07 7月, 2017 4 次提交
  27. 13 5月, 2017 1 次提交
  29. 04 5月, 2017 5 次提交
    • D
      mm, vmstat: suppress pcp stats for unpopulated zones in zoneinfo · 7dfb8bf3
      由 David Rientjes 提交于 
      After "mm, vmstat: print non-populated zones in zoneinfo",
/proc/zoneinfo will show unpopulated zones.

The per-cpu pageset statistics are not relevant for unpopulated zones
and can be potentially lengthy, so supress them when they are not
interesting.

Also moves lowmem reserve protection information above pcp stats since
it is relevant for all zones per vm.lowmem_reserve_ratio.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703061400500.46428@chino.kir.corp.google.comSigned-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7dfb8bf3
    • D
      mm, vmstat: print non-populated zones in zoneinfo · b2bd8598
      由 David Rientjes 提交于 
      Initscripts can use the information (protection levels) from
/proc/zoneinfo to configure vm.lowmem_reserve_ratio at boot.

vm.lowmem_reserve_ratio is an array of ratios for each configured zone
on the system.  If a zone is not populated on an arch, /proc/zoneinfo
suppresses its output.

This results in there not being a 1:1 mapping between the set of zones
emitted by /proc/zoneinfo and the zones configured by
vm.lowmem_reserve_ratio.

This patch shows statistics for non-populated zones in /proc/zoneinfo.
The zones exist and hold a spot in the vm.lowmem_reserve_ratio array.
Without this patch, it is not possible to determine which index in the
array controls which zone if one or more zones on the system are not
populated.

Remaining users of walk_zones_in_node() are unchanged.  Files such as
/proc/pagetypeinfo require certain zone data to be initialized properly
for display, which is not done for unpopulated zones.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703031451310.98023@chino.kir.corp.google.comSigned-off-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b2bd8598
    • S
      mm: move MADV_FREE pages into LRU_INACTIVE_FILE list · f7ad2a6c
      由 Shaohua Li 提交于 
      madv()'s MADV_FREE indicate pages are 'lazyfree'.  They are still
anonymous pages, but they can be freed without pageout.  To distinguish
these from normal anonymous pages, we clear their SwapBacked flag.

MADV_FREE pages could be freed without pageout, so they pretty much like
used once file pages.  For such pages, we'd like to reclaim them once
there is memory pressure.  Also it might be unfair reclaiming MADV_FREE
pages always before used once file pages and we definitively want to
reclaim the pages before other anonymous and file pages.

To speed up MADV_FREE pages reclaim, we put the pages into
LRU_INACTIVE_FILE list.  The rationale is LRU_INACTIVE_FILE list is tiny
nowadays and should be full of used once file pages.  Reclaiming
MADV_FREE pages will not have much interfere of anonymous and active
file pages.  And the inactive file pages and MADV_FREE pages will be
reclaimed according to their age, so we don't reclaim too many MADV_FREE
pages too.  Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also
means we can reclaim the pages without swap support.  This idea is
suggested by Johannes.

This patch doesn't move MADV_FREE pages to LRU_INACTIVE_FILE list yet to
avoid bisect failure, next patch will do it.

The patch is based on Minchan's original patch.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/2f87063c1e9354677b7618c647abde77b07561e5.1487965799.git.shli@fb.comSigned-off-by: NShaohua Li <shli@fb.com>
Suggested-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f7ad2a6c
    • J
      mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() · c822f622
      由 Johannes Weiner 提交于 
      NR_PAGES_SCANNED counts number of pages scanned since the last page free
event in the allocator.  This was used primarily to measure the
reclaimability of zones and nodes, and determine when reclaim should
give up on them.  In that role, it has been replaced in the preceding
patches by a different mechanism.

Being implemented as an efficient vmstat counter, it was automatically
exported to userspace as well.  It's however unlikely that anyone
outside the kernel is using this counter in any meaningful way.

Remove the counter and the unused pgdat_reclaimable().

Link: http://lkml.kernel.org/r/20170228214007.5621-8-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c822f622
    • J
      mm: fix 100% CPU kswapd busyloop on unreclaimable nodes · c73322d0
      由 Johannes Weiner 提交于 
      Patch series "mm: kswapd spinning on unreclaimable nodes - fixes and
cleanups".

Jia reported a scenario in which the kswapd of a node indefinitely spins
at 100% CPU usage.  We have seen similar cases at Facebook.

The kernel's current method of judging its ability to reclaim a node (or
whether to back off and sleep) is based on the amount of scanned pages
in proportion to the amount of reclaimable pages.  In Jia's and our
scenarios, there are no reclaimable pages in the node, however, and the
condition for backing off is never met.  Kswapd busyloops in an attempt
to restore the watermarks while having nothing to work with.

This series reworks the definition of an unreclaimable node based not on
scanning but on whether kswapd is able to actually reclaim pages in
MAX_RECLAIM_RETRIES (16) consecutive runs.  This is the same criteria
the page allocator uses for giving up on direct reclaim and invoking the
OOM killer.  If it cannot free any pages, kswapd will go to sleep and
leave further attempts to direct reclaim invocations, which will either
make progress and re-enable kswapd, or invoke the OOM killer.

Patch #1 fixes the immediate problem Jia reported, the remainder are
smaller fixlets, cleanups, and overall phasing out of the old method.

Patch #6 is the odd one out.  It's a nice cleanup to get_scan_count(),
and directly related to #5, but in itself not relevant to the series.

If the whole series is too ambitious for 4.11, I would consider the
first three patches fixes, the rest cleanups.

This patch (of 9):

Jia He reports a problem with kswapd spinning at 100% CPU when
requesting more hugepages than memory available in the system:

$ echo 4000 >/proc/sys/vm/nr_hugepages

top - 13:42:59 up  3:37,  1 user,  load average: 1.09, 1.03, 1.01
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us, 12.5 sy,  0.0 ni, 85.5 id,  2.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:  31371520 total, 30915136 used,   456384 free,      320 buffers
KiB Swap:  6284224 total,   115712 used,  6168512 free.    48192 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
   76 root      20   0       0      0      0 R 100.0 0.000 217:17.29 kswapd3

At that time, there are no reclaimable pages left in the node, but as
kswapd fails to restore the high watermarks it refuses to go to sleep.

Kswapd needs to back away from nodes that fail to balance.  Up until
commit 1d82de61 ("mm, vmscan: make kswapd reclaim in terms of
nodes") kswapd had such a mechanism.  It considered zones whose
theoretically reclaimable pages it had reclaimed six times over as
unreclaimable and backed away from them.  This guard was erroneously
removed as the patch changed the definition of a balanced node.

However, simply restoring this code wouldn't help in the case reported
here: there *are* no reclaimable pages that could be scanned until the
threshold is met.  Kswapd would stay awake anyway.

Introduce a new and much simpler way of backing off.  If kswapd runs
through MAX_RECLAIM_RETRIES (16) cycles without reclaiming a single
page, make it back off from the node.  This is the same number of shots
direct reclaim takes before declaring OOM.  Kswapd will go to sleep on
that node until a direct reclaimer manages to reclaim some pages, thus
proving the node reclaimable again.

[hannes@cmpxchg.org: check kswapd failure against the cumulative nr_reclaimed count]
  Link: http://lkml.kernel.org/r/20170306162410.GB2090@cmpxchg.org
[shakeelb@google.com: fix condition for throttle_direct_reclaim]
  Link: http://lkml.kernel.org/r/20170314183228.20152-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20170228214007.5621-2-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NShakeel Butt <shakeelb@google.com>
Reported-by: NJia He <hejianet@gmail.com>
Tested-by: NJia He <hejianet@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.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>
      c73322d0
  31. 20 4月, 2017 1 次提交
    • M
      mm: make mm_percpu_wq non freezable · 80d136e1
      由 Michal Hocko 提交于 
      Geert has reported a freeze during PM resume and some additional
debugging has shown that the device_resume worker cannot make a forward
progress because it waits for an event which is stuck waiting in
drain_all_pages:

  INFO: task kworker/u4:0:5 blocked for more than 120 seconds.
        Not tainted 4.11.0-rc7-koelsch-00029-g005882e5-dirty #3476
  "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  kworker/u4:0    D    0     5      2 0x00000000
  Workqueue: events_unbound async_run_entry_fn
    __schedule
    schedule
    schedule_timeout
    wait_for_common
    dpm_wait_for_superior
    device_resume
    async_resume
    async_run_entry_fn
    process_one_work
    worker_thread
    kthread
  [...]
  bash            D    0  1703   1694 0x00000000
    __schedule
    schedule
    schedule_timeout
    wait_for_common
    flush_work
    drain_all_pages
    start_isolate_page_range
    alloc_contig_range
    cma_alloc
    __alloc_from_contiguous
    cma_allocator_alloc
    __dma_alloc
    arm_dma_alloc
    sh_eth_ring_init
    sh_eth_open
    sh_eth_resume
    dpm_run_callback
    device_resume
    dpm_resume
    dpm_resume_end
    suspend_devices_and_enter
    pm_suspend
    state_store
    kernfs_fop_write
    __vfs_write
    vfs_write
    SyS_write
  [...]
  Showing busy workqueues and worker pools:
  [...]
  workqueue mm_percpu_wq: flags=0xc
    pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=0/0
      delayed: drain_local_pages_wq, vmstat_update
    pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=0/0
      delayed: drain_local_pages_wq BAR(1703), vmstat_update

Tetsuo has properly noted that mm_percpu_wq is created as WQ_FREEZABLE
so it is frozen this early during resume so we are effectively
deadlocked.  Fix this by dropping WQ_FREEZABLE when creating
mm_percpu_wq.  We really want to have it operational all the time.

Fixes: ce612879 ("mm: move pcp and lru-pcp draining into single wq")
Reported-and-tested-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Debugged-by: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      80d136e1
  33. 08 4月, 2017 1 次提交
  35. 01 4月, 2017 1 次提交
    • M
      mm: move mm_percpu_wq initialization earlier · 597b7305
      由 Michal Hocko 提交于 
      Yang Li has reported that drain_all_pages triggers a WARN_ON which means
that this function is called earlier than the mm_percpu_wq is
initialized on arm64 with CMA configured:

  WARNING: CPU: 2 PID: 1 at mm/page_alloc.c:2423 drain_all_pages+0x244/0x25c
  Modules linked in:
  CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.11.0-rc1-next-20170310-00027-g64dfbc5 #127
  Hardware name: Freescale Layerscape 2088A RDB Board (DT)
  task: ffffffc07c4a6d00 task.stack: ffffffc07c4a8000
  PC is at drain_all_pages+0x244/0x25c
  LR is at start_isolate_page_range+0x14c/0x1f0
  [...]
   drain_all_pages+0x244/0x25c
   start_isolate_page_range+0x14c/0x1f0
   alloc_contig_range+0xec/0x354
   cma_alloc+0x100/0x1fc
   dma_alloc_from_contiguous+0x3c/0x44
   atomic_pool_init+0x7c/0x208
   arm64_dma_init+0x44/0x4c
   do_one_initcall+0x38/0x128
   kernel_init_freeable+0x1a0/0x240
   kernel_init+0x10/0xfc
   ret_from_fork+0x10/0x20

Fix this by moving the whole setup_vmstat which is an initcall right now
to init_mm_internals which will be called right after the WQ subsystem
is initialized.

Link: http://lkml.kernel.org/r/20170315164021.28532-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reported-by: NYang Li <pku.leo@gmail.com>
Tested-by: NYang Li <pku.leo@gmail.com>
Tested-by: NXiaolong Ye <xiaolong.ye@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      597b7305
  37. 10 3月, 2017 1 次提交
  39. 23 2月, 2017 1 次提交
  41. 02 12月, 2016 1 次提交