fix #26198889

commit 26cf52229efc87e2effa9d788f9b33c40fb3358a linux-next

During our testing, we found a case that shares no longer
working correctly, the cgroup topology is like:

  /sys/fs/cgroup/cpu/A		(shares=102400)
  /sys/fs/cgroup/cpu/A/B	(shares=2)
  /sys/fs/cgroup/cpu/A/B/C	(shares=1024)

  /sys/fs/cgroup/cpu/D		(shares=1024)
  /sys/fs/cgroup/cpu/D/E	(shares=1024)
  /sys/fs/cgroup/cpu/D/E/F	(shares=1024)

The same benchmark is running in group C & F, no other tasks are
running, the benchmark is capable to consumed all the CPUs.

We suppose the group C will win more CPU resources since it could
enjoy all the shares of group A, but it's F who wins much more.

The reason is because we have group B with shares as 2, since
A->cfs_rq.load.weight == B->se.load.weight == B->shares/nr_cpus,
so A->cfs_rq.load.weight become very small.

And in calc_group_shares() we calculate shares as:

  load = max(scale_load_down(cfs_rq->load.weight),
cfs_rq->avg.load_avg);
  shares = (tg_shares * load) / tg_weight;

Since the 'cfs_rq->load.weight' is too small, the load become 0
after scale down, although 'tg_shares' is 102400, shares of the se
which stand for group A on root cfs_rq become 2.

While the se of D on root cfs_rq is far more bigger than 2, so it
wins the battle.

Thus when scale_load_down() scale real weight down to 0, it's no
longer telling the real story, the caller will have the wrong
information and the calculation will be buggy.

This patch add check in scale_load_down(), so the real weight will
be >= MIN_SHARES after scale, after applied the group C wins as
expected.
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NMichael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NVincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/38e8e212-59a1-64b2-b247-b6d0b52d8dc1@linux.alibaba.comAcked-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>

fix #25892693

commit 26a8b12747c975b33b4a82d62e4a307e1c07f31b upstream

Currently, there is a potential race between distribute_cfs_runtime()
and assign_cfs_rq_runtime(). Race happens when cfs_b->runtime is read,
distributes without holding lock and finds out there is not enough
runtime to charge against after distribution. Because
assign_cfs_rq_runtime() might be called during distribution, and use
cfs_b->runtime at the same time.

Fibtest is the tool to test this race. Assume all gcfs_rq is throttled
and cfs period timer runs, slow threads might run and sleep, returning
unused cfs_rq runtime and keeping min_cfs_rq_runtime in their local
pool. If all this happens sufficiently quickly, cfs_b->runtime will drop
a lot. If runtime distributed is large too, over-use of runtime happens.

A runtime over-using by about 70 percent of quota is seen when we
test fibtest on a 96-core machine. We run fibtest with 1 fast thread and
95 slow threads in test group, configure 10ms quota for this group and
see the CPU usage of fibtest is 17.0%, which is far from than the
expected 10%.

On a smaller machine with 32 cores, we also run fibtest with 96
threads. CPU usage is more than 12%, which is also more than expected
10%. This shows that on similar workloads, this race do affect CPU
bandwidth control.

Solve this by holding lock inside distribute_cfs_runtime().

Fixes: c06f04c7 ("sched: Fix potential near-infinite distribute_cfs_runtime() loop")
Signed-off-by: NHuaixin Chang <changhuaixin@linux.alibaba.com>
Reviewed-by: NBen Segall <bsegall@google.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Link: https://lore.kernel.org/lkml/20200325092602.22471-1-changhuaixin@linux.alibaba.com/Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>

to #26424323

task_css() should be protected by rcu, fix several callers.

Fixes: 1f49a738 ("alinux: psi: Support PSI under cgroup v1")
Acked-by: NMichael Wang <yun.wany@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NYihao Wu <wuyihao@linux.alibaba.com>
Acked-by: NYang Shi <yang.shi@linux.alibaba.com>

to #26616987

Disable CONFIG_NFS_V3_ACL and CONFIG_NFSD_V3_ACL for aarch64,
to be same with x86
Signed-off-by: NChunmei Xu <xuchunmei@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

to #26788859

We've met several real-world issues that the child reaper
(i.e. systemd) gets stuck in some aborted status and cann't
reap its zombie children, so we provide the interface to do
By specified the pid.
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Nzhongjiang-ali <zhongjiang-ali@linux.alibaba.com>

to #26424311

Commit 5028e358 ("alinux: mm: oom_kill: show killed task's cgroup
info in global oom") introduces an potential null pointer reference. It
is because the task 'p' maybe an null pointer in same code path.

Fixes: 5028e358 ("alinux: mm: oom_kill: show killed task's cgroup
info in global oom")
Signed-off-by: Nzhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

task #25182720

commit 12e967fd8e4e6c3d275b4c69c890adc838891300 upstream

Jann has brought up a very interesting point [1].  While shared pages
are excluded from MADV_PAGEOUT normally, CoW pages can be easily
reclaimed that way.  This can lead to all sorts of hard to debug
problems.  E.g.  performance problems outlined by Daniel [2].

There are runtime environments where there is a substantial memory
shared among security domains via CoW memory and a easy to reclaim way
of that memory, which MADV_{COLD,PAGEOUT} offers, can lead to either
performance degradation in for the parent process which might be more
privileged or even open side channel attacks.

The feasibility of the latter is not really clear to me TBH but there is
no real reason for exposure at this stage.  It seems there is no real
use case to depend on reclaiming CoW memory via madvise at this stage so
it is much easier to simply disallow it and this is what this patch
does.  Put it simply MADV_{PAGEOUT,COLD} can operate only on the
exclusively owned memory which is a straightforward semantic.

[1] http://lkml.kernel.org/r/CAG48ez0G3JkMq61gUmyQAaCq=_TwHbi1XKzWRooxZkv08PQKuw@mail.gmail.com
[2] http://lkml.kernel.org/r/CAKOZueua_v8jHCpmEtTB6f3i9e2YnmX4mqdYVWhV4E=Z-n+zRQ@mail.gmail.com

Fixes: 9c276cc65a58 ("mm: introduce MADV_COLD")
Reported-by: NJann Horn <jannh@google.com>
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200312082248.GS23944@dhcp22.suse.czSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26782094

Pin code section of process in memory for the corresponding
VMAs like mlock does.

Usage:
- pin process "PID"
  echo PID > /proc/unevictable/add_pid
- unpin it
  echo PID > /proc/unevictable/del_pid
- show all pinned process pids
  cat /proc/unevictable/add_pid

For easy maintenance, we place it in kernel because it has no
side effect if don't use it.
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>

fix #26416752

The idle page age shown in idle_page_stats is one scan period behind the
theoretical idle age.  The cause is that kidled_inc_page_age returned
the ancient value, instead of the latest value, which leads to not
accounting in corresponding memcg.

This makes kidled_inc_page_age return the increased age of the page,
i.e., the latest page age, when KIDLED_AGE_NOT_IN_PAGE_FLAGS is not set.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

fix #25820910

commit 93b3a674485f6a4b8ffff85d1682d5e8b7c51560 upstream.

pagetypeinfo_showfree_print is called by zone->lock held in irq mode.
This is not really nice because it blocks both any interrupts on that
cpu and the page allocator.  On large machines this might even trigger
the hard lockup detector.

Considering the pagetypeinfo is a debugging tool we do not really need
exact numbers here.  The primary reason to look at the outuput is to see
how pageblocks are spread among different migratetypes and low number of
pages is much more interesting therefore putting a bound on the number
of pages on the free_list sounds like a reasonable tradeoff.

The new output will simply tell
  [...]
  Node    6, zone   Normal, type      Movable >100000 >100000 >100000 >100000  41019  31560  23996  10054   3229    983    648

instead of
  Node    6, zone   Normal, type      Movable 399568 294127 221558 102119  41019  31560  23996  10054   3229    983    648

The limit has been chosen arbitrary and it is a subject of a future
change should there be a need for that.

While we are at it, also drop the zone lock after each free_list
iteration which will help with the IRQ and page allocator responsiveness
even further as the IRQ lock held time is always bound to those 100k
pages.

[akpm@linux-foundation.org: tweak comment text, per David Hildenbrand]
Link: http://lkml.kernel.org/r/20191025072610.18526-3-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NWaiman Long <longman@redhat.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Acked-by: NRafael Aquini <aquini@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Roman Gushchin <guro@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

Specifically, replace `val / 1000000` with `val >> 20` to do the
optimization.

This also fixes the possible compiling error when building with
ARCH=i386, which reports undefined reference to `__udivdi3`.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

to #26424368

This reworks memsli "start", "end", "update" interfaces to make it more
clear and symmetrical, by merging "update" action into "end", just like
what psi_memstall_{enter, leave} does.

Now the latency probe pattern of memsli is as follows:

memcg_lat_stat_start(&start);
/* kernel codes being probed */
memcg_lat_stat_end(MEM_LAT_XXX, start);

This also formats the codes and fixes the warning(s) produced when
CONFIG_MEMSLI is not set.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

to #26424368

Enable CONFIG_MEMSLI by default.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

This introduces the new bool kconfig MEMSLI, determining whether the
memsli (memory latency histogram) feature should be built-in or not.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

Since memsli also records latency histogram for swapout and swapin,
which are NOT in the slow memory path, the overhead of memsli could
be nonnegligible in some specific scenarios.

For example, in scenarios with frequent swapping out and in, memsli
could introduce overhead of ~1% of total run time of the synthetic
testcase.

This adds procfs interface for memsli switch. The memsli feature is
enabled by default, and you can now disable it by:

$ echo 0 > /proc/memsli/enabled

Apparently, you can check current memsli switch status by:

$ cat /proc/memsli/enabled

Note that disabling memsli at runtime will NOT clear the existing
latency histogram. You still need to manually reset the specified
latency histogram(s) by echo 0 into the corresponding cgroup control
file(s).
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

CPU hotplug may occur in some business scenarios, resulting in
unavailable per-cpu memsli/exstat data on those non-present or
offline CPU(s).

This fixes the potential problem by using for_each_possible_cpu
macro when gathering per-cpu memsli/exstat data.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

to #26424368

Commit 6202ab24 ("mm, memcg: throttle
allocators when failing reclaim over memory.high") introduces explicit
throttling when reclaim is failing to keep memcg size contained at the
memory.high setting.

Just account this latency on memcg direct reclaim latency histogram.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>

to #26424368

Probe and calculate the latency of global swapout, memcg swapout and
swapin respectively, and then group into the latency histogram in struct
mem_cgroup.

Note that the latency in each memcg is aggregated from all child memcgs.

Usage:

$ cat memory.direct_swapout_global_latency
0-1ms:  98313
1-5ms:  0
5-10ms:         0
10-100ms:       0
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      52

Each line is the count of global swapout within the appropriate latency
range.

To clear the latency histogram:

$ echo 0 > memory.direct_swapout_global_latency
$ cat memory.direct_swapout_global_latency
0-1ms:  0
1-5ms:  0
5-10ms:         0
10-100ms:       0
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      0

The usage of memory.direct_swapout_memcg_latency and
memory.direct_swapin_latency is the same as
memory.direct_swapout_global_latency.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

We account reclaim_high in mem_cgroup_handle_over_high into memcg direct
reclaim latency histogram, due to possible future use of memory.high.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

Since there are features other than memcg direct reclaim which also
invoke try_to_free_mem_cgroup_pages, such as zombie memcg reaper, memcg
kswapd, etc,.  Move the latency probe point for memcg direct reclaim
from function try_to_free_mem_cgroup_pages to function try_charge, in
order to distinguish memcg direct reclaim.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

There are some duplicate codes in the original implementation of memory
latency histogram, such as {x, y, z}_show, and {x, y, z}_write, where x,
y, z represents various types of memory latency.

This reworks common codes of memory latency histogram to make it easier
to add more types of memory latency later.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

Probe and calculate the latency of direct compact, and then group into
the latency histogram in struct mem_cgroup.

Note that the latency in each memcg is aggregated from all child memcgs.

Usage:

$ cat memory.direct_compact_latency
0-1ms:  1176
1-5ms:  259
5-10ms:         17
10-100ms:       10
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      921

Each line is the count of direct compact within the appropriate latency
range.

To clear the latency histogram:

$ echo 0 > memory.direct_compact_latency
$ cat memory.direct_compact_latency
0-1ms:  0
1-5ms:  0
5-10ms:         0
10-100ms:       0
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      0
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

to #26424368

Probe and calculate the latency of global direct reclaim and memcg
direct reclaim, respectively, and then group into the latency histogram
in struct mem_cgroup. Besides, the total latency is accumulated each
time the histogram is updated.

Note that the latency in each memcg is aggregated from all child memcgs.

Usage:

$ cat memory.direct_reclaim_global_latency
0-1ms:  228
1-5ms:  283
5-10ms:         0
10-100ms:       0
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      539

Each line is the count of global direct reclaim within the appropriate
latency range.

To clear the latency histogram:

$ echo 0 > memory.direct_reclaim_global_latency
$ cat memory.direct_reclaim_global_latency
0-1ms:  0
1-5ms:  0
5-10ms:         0
10-100ms:       0
100-500ms:      0
500-1000ms:     0
>=1000ms:       0
total(ms):      0

The usage of memory.direct_reclaim_memcg_latency is the same as
memory.direct_reclaim_global_latency.
Signed-off-by: NXu Yu <xuyu@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>

fix #24463023

This reverts commit adb03115.

Related Links:
    https://lkml.org/lkml/2019/7/24/243
    https://lore.kernel.org/lkml/b0160f4b-b996-b0ee-405a-3d5f1866272e@gmail.com/
    https://lore.kernel.org/lkml/20181101172739.GA3196@hirez.programming.kicks-ass.net/

test methods:
   1. add dummy net dev. "ip link add pps_dummy0 type dummy"
   2. set the dummy dev with addr 10.10.10.1
   3. send numerous udp packets to 10.10.10.2(fake addr) by dummy dev

test command: sockperf tp -m 14 -t 20 --mps=max -i 10.10.10.2 -p 11111

By default, the ip_idents_reserve function will be called to distribute the
identities of the identities in the ip layer without the DF flag. Use this
method to stress test this function.

After testing under vm, after the concurrent CPU exceeds 12, the old patch pps
will no longer rise. The data for concurrent CPU 32 is as follows:

test without atomic_add_return:
    11:32:10 AM pps_dummy0      0.00 8008897.00      0.00 437986.55      0.00      0.00      0.00
    11:32:11 AM pps_dummy0      0.00 7992910.00      0.00 437112.27      0.00      0.00      0.00
    11:32:12 AM pps_dummy0      0.00 7982553.00      0.00 436545.87      0.00      0.00      0.00
    11:32:13 AM pps_dummy0      0.00 7977757.00      0.00 436283.59      0.00      0.00      0.00
    11:32:14 AM pps_dummy0      0.00 7968355.00      0.00 435769.41      0.00      0.00      0.00

test with atomic_add_return:
    11:33:20 AM pps_dummy0      0.00 16024069.00      0.00 876316.27      0.00      0.00      0.00
    11:33:21 AM pps_dummy0      0.00 16024252.00      0.00 876326.28      0.00      0.00      0.00
    11:33:22 AM pps_dummy0      0.00 16021639.00      0.00 876183.38      0.00      0.00      0.00
    11:33:23 AM pps_dummy0      0.00 16018738.00      0.00 876024.73      0.00      0.00      0.00
    11:33:24 AM pps_dummy0      0.00 16022333.00      0.00 876221.34      0.00      0.00      0.00
    11:33:25 AM pps_dummy0      0.00 16028147.00      0.00 876539.29      0.00      0.00      0.00
Signed-off-by: Nxuanzhuo <xuanzhuo@linux.alibaba.com>
Acked-by: NDust Li <dust.li@linux.alibaba.com>

to #26589565

commit 5790b53390e18fdd21e70776e46d058c05eda2f2 upstream

VQs without a name specified are not valid; they are skipped in the
later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
loop above that counts the required number of vectors previously still
counted any queue with a non-NULL callback as needing a vector.

Add a check to the per_vq_vectors loop so that vectors with no name are
not counted to make the two loops consistent.  This prevents
over-counting unnecessary vectors (e.g. for features which were not
negotiated with the device).

Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Signed-off-by: NDaniel Verkamp <dverkamp@chromium.org>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NWang, Wei W <wei.w.wang@intel.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

Added extra "callbacks[VIRTIO_BALLOON_VQ_REPORTING] = NULL".

commit 303090b513fd1ee45aa1536b71a3838dc054bc05 upstream

Ensure that elements of the callbacks array that correspond to
unavailable features are set to NULL; previously, they would be left
uninitialized.

Since the corresponding names array elements were explicitly set to
NULL, the uninitialized callback pointers would not actually be
dereferenced; however, the uninitialized callbacks elements would still
be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
vectors required.

Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Signed-off-by: NDaniel Verkamp <dverkamp@chromium.org>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

Add documentation for free page reporting.  Currently the only consumer is
virtio-balloon, however it is possible that other drivers might make use
of this so it is best to add a bit of documetation explaining at a high
level how to use the API.

Link: http://lkml.kernel.org/r/20200211224730.29318.43815.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

In order to keep ourselves from reporting pages that are just going to be
reused again in the case of heavy churn we can put a limit on how many
total pages we will process per pass.  Doing this will allow the worker
thread to go into idle much more quickly so that we avoid competing with
other threads that might be allocating or freeing pages.

The logic added here will limit the worker thread to no more than one
sixteenth of the total free pages in a given area per list.  Once that
limit is reached it will update the state so that at the end of the pass
we will reschedule the worker to try again in 2 seconds when the memory
churn has hopefully settled down.

Again this optimization doesn't show much of a benefit in the standard
case as the memory churn is minmal.  However with page allocator shuffling
enabled the gain is quite noticeable.  Below are the results with a THP
enabled version of the will-it-scale page_fault1 test showing the
improvement in iterations for 16 processes or threads.

Without:
tasks   processes       processes_idle  threads         threads_idle
16      8283274.75      0.17            5594261.00      38.15

With:
tasks   processes       processes_idle  threads         threads_idle
16      8767010.50      0.21            5791312.75      36.98

Link: http://lkml.kernel.org/r/20200211224719.29318.72113.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

Rather than walking over the same pages again and again to get to the
pages that have yet to be reported we can save ourselves a significant
amount of time by simply rotating the list so that when we have a full
list of reported pages the head of the list is pointing to the next
non-reported page.  Doing this should save us some significant time when
processing each free list.

This doesn't gain us much in the standard case as all of the non-reported
pages should be near the top of the list already.  However in the case of
page shuffling this results in a noticeable improvement.  Below are the
will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without
this patch.

Without:
tasks   processes       processes_idle  threads         threads_idle
16      8093776.25      0.17            5393242.00      38.20

With:
tasks   processes       processes_idle  threads         threads_idle
16      8283274.75      0.17            5594261.00      38.15

Link: http://lkml.kernel.org/r/20200211224708.29318.16862.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

Add support for the page reporting feature provided by virtio-balloon.
Reporting differs from the regular balloon functionality in that is is
much less durable than a standard memory balloon.  Instead of creating a
list of pages that cannot be accessed the pages are only inaccessible
while they are being indicated to the virtio interface.  Once the
interface has acknowledged them they are placed back into their respective
free lists and are once again accessible by the guest system.

Unlike a standard balloon we don't inflate and deflate the pages.  Instead
we perform the reporting, and once the reporting is completed it is
assumed that the page has been dropped from the guest and will be faulted
back in the next time the page is accessed.

Link: http://lkml.kernel.org/r/20200211224657.29318.68624.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

Currently the page poisoning setting wasn't being enabled unless free page
hinting was enabled.  However we will need the page poisoning tracking
logic as well for free page reporting.  As such pull it out and make it a
separate bit of config in the probe function.

In addition we need to add support for the more recent init_on_free
feature which expects a behavior similar to page poisoning in that we
expect the page to be pre-zeroed.

Link: http://lkml.kernel.org/r/20200211224646.29318.695.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

In order to pave the way for free page reporting in virtualized
environments we will need a way to get pages out of the free lists and
identify those pages after they have been returned.  To accomplish this,
this patch adds the concept of a Reported Buddy, which is essentially
meant to just be the Uptodate flag used in conjunction with the Buddy page
type.

To prevent the reported pages from leaking outside of the buddy lists I
added a check to clear the PageReported bit in the del_page_from_free_list
function.  As a result any reported page that is split, merged, or
allocated will have the flag cleared prior to the PageBuddy value being
cleared.

The process for reporting pages is fairly simple.  Once we free a page
that meets the minimum order for page reporting we will schedule a
worker thread to start 2s or more in the future.  That worker thread will begin
working from the lowest supported page reporting order up to MAX_ORDER - 1
pulling unreported pages from the free list and storing them in the
scatterlist.

When processing each individual free list it is necessary for the worker
thread to release the zone lock when it needs to stop and report the full
scatterlist of pages.  To reduce the work of the next iteration the worker
thread will rotate the free list so that the first unreported page in
the free list becomes the first entry in the list.

It will then call a reporting function providing information on how many
entries are in the scatterlist.  Once the function completes it will
return the pages to the free area from which they were allocated and start
over pulling more pages from the free areas until there are no longer
enough pages to report on to keep the worker busy, or we have processed as
many pages as were contained in the free area when we started processing
the list.

The worker thread will work in a round-robin fashion making its way though
each zone requesting reporting, and through each reportable free list
within that zone.  Once all free areas within the zone have been processed
it will check to see if there have been any requests for reporting while
it was processing.  If so it will reschedule the worker thread to start up
again in roughly 2s and exit.

Link: http://lkml.kernel.org/r/20200211224635.29318.19750.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit 624f58d8f4639676d2fa1238425ab0148d501c4a upstream linux-next.

There are cases where we would benefit from avoiding having to go
through
the allocation and free cycle to return an isolated page.

Examples for this might include page poisoning in which we isolate a page
and then put it back in the free list without ever having actually
allocated it.

This will enable us to also avoid notifiers for the future free page
reporting which will need to avoid retriggering page reporting when
returning pages that have been reported on.

Link: http://lkml.kernel.org/r/20200211224624.29318.89287.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

In order to enable the use of the zone from the list manipulator
functions
I will need access to the zone pointer.  As it turns out most of the
accessors were always just being directly passed &zone->free_area[order]
anyway so it would make sense to just fold that into the function itself
and pass the zone and order as arguments instead of the free area.

In order to be able to reference the zone we need to move the declaration
of the functions down so that we have the zone defined before we define
the list manipulation functions.  Since the functions are only used in the
file mm/page_alloc.c we can just move them there to reduce noise in the
header.

Link: http://lkml.kernel.org/r/20200211224613.29318.43080.stgit@localhost.localdomainSigned-off-by: NAlexander Duyck <alexander.h.duyck@linux.intel.com>
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Reviewed-by: NDan Williams <dan.j.williams@intel.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Reviewed-by: NPankaj Gupta <pagupta@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit b03641af680959df57c275a80ff0dc116627c7ae upstream

In preparation for runtime randomization of the zone lists, take all
(well, most of) the list_*() functions in the buddy allocator and put
them in helper functions.  Provide a common control point for injecting
additional behavior when freeing pages.

[dan.j.williams@intel.com: fix buddy list helpers]
  Link: http://lkml.kernel.org/r/155033679702.1773410.13041474192173212653.stgit@dwillia2-desk3.amr.corp.intel.com
[vbabka@suse.cz: remove del_page_from_free_area() migratetype parameter]
  Link: http://lkml.kernel.org/r/4672701b-6775-6efd-0797-b6242591419e@suse.cz
Link: http://lkml.kernel.org/r/154899812264.3165233.5219320056406926223.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Tested-by: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

The list_is_first() and list_rotate_to_front() functions are needed by
free page hinting.  list_is_first() was used by i915 driver, so moved it
to common header file.

Backported list_rotate_to_front() from commit a16b53849913 ("list: add
function list_rotate_to_front()"). Not backport the whole patch, just
copy the implementation of the function.
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit 6c22dc61c76b7e7d355f1697ba0ecf26d1334ba6 upstream

When unloading the driver while hinting is in progress, we will not
release the free page blocks back to MM, resulting in a memory leak.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Liang Li <liang.z.li@intel.com>
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200205163402.42627-2-david@redhat.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit a229989d975eb926076307c1f2f5e4c6111768e7 upstream

Some vqs may not need to be allocated when their related feature bits
are disabled. So callers may pass in such vqs with "names = NULL".
Then we skip such vq allocations.
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit ddbeac07a39a81d82331a312d0578fab94fccbf1 upstream

When find_vqs, there will be no vq[i] allocation if its corresponding
names[i] is NULL. For example, the caller may pass in names[i] (i=4)
with names[2] being NULL because the related feature bit is turned off,
so technically there are 3 queues on the device, and name[4] should
correspond to the 3rd queue on the device.

So we use queue_idx as the queue index, which is increased only when the
queue exists.
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

to #26589565

commit 2e991629bcf55a43681aec1ee096eeb03cf81709 upstream

The VIRTIO_BALLOON_F_PAGE_POISON feature bit is used to indicate if the
guest is using page poisoning. Guest writes to the poison_val config
field to tell host about the page poisoning value that is in use.
Suggested-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>