commit 6e693b3ffecb0b478c7050b44a4842854154f715 upstream.

Commit 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'")
makes the access_ok() check part of the user_access_begin() preceding a
series of 'unsafe' accesses.  This has the desirable effect of ensuring
that all 'unsafe' accesses have been range-checked, without having to
pick through all of the callsites to verify whether the appropriate
checking has been made.

However, the consolidated range check does not inhibit speculation, so
it is still up to the caller to ensure that they are not susceptible to
any speculative side-channel attacks for user addresses that ultimately
fail the access_ok() check.

This is an oversight, so use __uaccess_begin_nospec() to ensure that
speculation is inhibited until the access_ok() check has passed.
Reported-by: NJulien Thierry <julien.thierry@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit 594cc251fdd0d231d342d88b2fdff4bc42fb0690 upstream.

Originally, the rule used to be that you'd have to do access_ok()
separately, and then user_access_begin() before actually doing the
direct (optimized) user access.

But experience has shown that people then decide not to do access_ok()
at all, and instead rely on it being implied by other operations or
similar.  Which makes it very hard to verify that the access has
actually been range-checked.

If you use the unsafe direct user accesses, hardware features (either
SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged
Access Never - on ARM) do force you to use user_access_begin().  But
nothing really forces the range check.

By putting the range check into user_access_begin(), we actually force
people to do the right thing (tm), and the range check vill be visible
near the actual accesses.  We have way too long a history of people
trying to avoid them.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

[ Shile: fix following conflicts by adding a dummy arguments ]
Conflicts:
	kernel/compat.c
	kernel/exit.c
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>

commit 0b2c8f8b6b0c7530e2866c95862546d0da2057b0 upstream.

When commit fddcd00a49e9 ("drm/i915: Force the slow path after a
user-write error") unified the error handling for various user access
problems, it didn't do the user_access_end() that is needed for the
unsafe_put_user() case.

It's not a huge deal: a missed user_access_end() will only mean that
SMAP protection isn't active afterwards, and for the error case we'll be
returning to user mode soon enough anyway.  But it's wrong, and adding
the proper user_access_end() is trivial enough (and doing it for the
other error cases where it isn't needed doesn't hurt).

I noticed it while doing the same prep-work for changing
user_access_begin() that precipitated the access_ok() changes in commit
96d4f267e40f ("Remove 'type' argument from access_ok() function").

Fixes: fddcd00a49e9 ("drm/i915: Force the slow path after a user-write error")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@kernel.org # v4.20
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit fddcd00a49e9122a3579247151e9cb3ce5a1a36e upstream.

If we fail to write the user relocation back when it is changed, force
ourselves to take the slow relocation path where we can handle faults in
the write path. There is still an element of dubiousness as having
patched up the batch to use the correct offset, it no longer matches the
presumed_offset in the relocation, so a second pass may miss any changes
in layout.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180903083337.13134-3-chris@chris-wilson.co.ukSigned-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit 3b9aadf7278d16d7bed4d5d808501065f70898d8 upstream.

get_mempolicy(MPOL_F_NODE|MPOL_F_ADDR) called a get_user_pages that would
not be waiting for userfaults before failing and it would hit on a SIGBUS
instead.  Using get_user_pages_locked/unlocked instead will allow
get_mempolicy to allow userfaults to resolve the fault and fill the hole,
before grabbing the node id of the page.

If the user calls get_mempolicy() with MPOL_F_ADDR | MPOL_F_NODE for an
address inside an area managed by uffd and there is no page at that
address, the page allocation from within get_mempolicy() will fail
because get_user_pages() does not allow for page fault retry required
for uffd; the user will get SIGBUS.

With this patch, the page fault will be resolved by the uffd and the
get_mempolicy() will continue normally.

Background:

Via code review, previously the syscall would have returned -EFAULT
(vm_fault_to_errno), now it will block and wait for an userfault (if
it's waken before the fault is resolved it'll still -EFAULT).

This way get_mempolicy will give a chance to an "unaware" app to be
compliant with userfaults.

The reason this visible change is that becoming "userfault compliant"
cannot regress anything: all other syscalls including read(2)/write(2)
had to become "userfault compliant" long time ago (that's one of the
things userfaultfd can do that PROT_NONE and trapping segfaults can't).

So this is just one more syscall that become "userfault compliant" like
all other major ones already were.

This has been happening on virtio-bridge dpdk process which just called
get_mempolicy on the guest space post live migration, but before the
memory had a chance to be migrated to destination.

I didn't run an strace to be able to show the -EFAULT going away, but
I've the confirmation of the below debug aid information (only visible
with CONFIG_DEBUG_VM=y) going away with the patch:

    [20116.371461] FAULT_FLAG_ALLOW_RETRY missing 0
    [20116.371464] CPU: 1 PID: 13381 Comm: vhost-events Not tainted 4.17.12-200.fc28.x86_64 #1
    [20116.371465] Hardware name: LENOVO 20FAS2BN0A/20FAS2BN0A, BIOS N1CET54W (1.22 ) 02/10/2017
    [20116.371466] Call Trace:
    [20116.371473]  dump_stack+0x5c/0x80
    [20116.371476]  handle_userfault.cold.37+0x1b/0x22
    [20116.371479]  ? remove_wait_queue+0x20/0x60
    [20116.371481]  ? poll_freewait+0x45/0xa0
    [20116.371483]  ? do_sys_poll+0x31c/0x520
    [20116.371485]  ? radix_tree_lookup_slot+0x1e/0x50
    [20116.371488]  shmem_getpage_gfp+0xce7/0xe50
    [20116.371491]  ? page_add_file_rmap+0x1a/0x2c0
    [20116.371493]  shmem_fault+0x78/0x1e0
    [20116.371495]  ? filemap_map_pages+0x3a1/0x450
    [20116.371498]  __do_fault+0x1f/0xc0
    [20116.371500]  __handle_mm_fault+0xe2e/0x12f0
    [20116.371502]  handle_mm_fault+0xda/0x200
    [20116.371504]  __get_user_pages+0x238/0x790
    [20116.371506]  get_user_pages+0x3e/0x50
    [20116.371510]  kernel_get_mempolicy+0x40b/0x700
    [20116.371512]  ? vfs_write+0x170/0x1a0
    [20116.371515]  __x64_sys_get_mempolicy+0x21/0x30
    [20116.371517]  do_syscall_64+0x5b/0x160
    [20116.371520]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

The above harmless debug message (not a kernel crash, just a
dump_stack()) is shown with CONFIG_DEBUG_VM=y to more quickly identify
and improve kernel spots that may have to become "userfaultfd
compliant" like this one (without having to run an strace and search
for syscall misbehavior).  Spots like the above are more closer to a
kernel bug for the non-cooperative usages that Mike focuses on, than
for for dpdk qemu-cooperative usages that reproduced it, but it's still
nicer to get this fixed for dpdk too.

The part of the patch that caused me to think is only the
implementation issue of mpol_get, but it looks like it should work safe
no matter the kind of mempolicy structure that is (the default static
policy also starts at 1 so it'll go to 2 and back to 1 without crashing
everything at 0).

[rppt@linux.vnet.ibm.com: changelog addition]
  http://lkml.kernel.org/r/20180904073718.GA26916@rapoport-lnx
Link: http://lkml.kernel.org/r/20180831214848.23676-1-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NMaxime Coquelin <maxime.coquelin@redhat.com>
Tested-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

During the module initialization phase, entropy will be added
to entropy pool for every interrupt, the change should speed up
initialization of the random module.

Before optimization:
[   22.180236] random: crng init done

After optimization:
[    1.474832] random: crng init done
Signed-off-by: NXingjun Liu <xingjun.lxj@alibaba-inc.com>
Reviewed-by: NLiu Jiang <gerry@linux.alibaba.com>
Reviewed-by: NCaspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>

Add random entropy with the module parameter as the initialization
seed when the kernel startup.

For guest OS working in VM, the random entropy will be less,
it cause the random module to initialize very slowly, and if
the application which running in guest os gets a certain amount of
random numbers in the initialization phase, it will be blocked.

This patch allows the VMM to provide a certain amount of random seed
when starting guest OS, speeding up the initialization of the entire
guest OS random module.

Before optimization:
[   22.180236] random: crng init done

After optimization:
[    1.553362] random: crng init done
Signed-off-by: NXingjun Liu <xingjun.lxj@alibaba-inc.com>
Reviewed-by: NLiu Jiang <gerry@linux.alibaba.com>
Reviewed-by: NCaspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>

commit 4ab526468344c11d2d1807ae95feb1f5305dc014 upstream.

This driver is Intel-only so loading on anything which is not Intel is
pointless. Prevent it from doing so.

While at it, correct the "not supported" print statement to say CPU
"model" which is what that test does.

Fixes: 076b862c7e44 (cpufreq: intel_pstate: Add reasons for failure and debug messages)
Suggested-by: NErwan Velu <e.velu@criteo.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Renninger <trenn@suse.de>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Acked-by: NMichael Wang <yun.wang@linux.alibaba.com>

commit 076b862c7e4409d2dcacfda19f7eaf8d07ab9200 upstream.

The init code path has several exceptions where the driver can
decide not to load.

As CONFIG_X86_INTEL_PSTATE is generally set to Y, the return code is
not reachable.  The initialization code is neither verbose of the
reason why it did choose to prematurely exit, so it is difficult for
a user to determine, on a given platform, why the driver didn't load
properly.

This patch is about reporting to the user the reason/context of why
the driver failed to load.  That is a precious hint when debugging
a platform.
Signed-off-by: NErwan Velu <e.velu@criteo.com>
[ rjw: Subject & changelog, minor fixups ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Acked-by: NMichael Wang <yun.wang@linux.alibaba.com>

commit af3b7379e2d709f2d7c6966b8a6f5ec6bd134241 upstream.

Force HWP Request MAX = HWP Request MIN = HWP Capability MIN and EPP to
0xFF. In this way the performance limits on the offlined CPU will not
influence performance limits on its sibling CPU, which is still online.

If the sibling CPU is calling for higher performance, it will impact the
max core performance. Here core performance will follow higher of the
performance requests from each sibling.
Reported-and-tested-by: NChen Yu <yu.c.chen@intel.com>
Signed-off-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Acked-by: NMichael Wang <yun.wang@linux.alibaba.com>

commit 075c18c3e124a1511ebc10a89f1858c8a77dcb01 upstream.

Provides useful context about bio splits in blktrace.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 6548c7c538e5658cbce686c2dd1a9b4f5398bf34 upstream.

Otherwise targets that don't support/expect IO splitting could resubmit
bios using code paths with unnecessary IO splitting complexity.

Depends-on: 24113d487843 ("dm: avoid indirect call in __dm_make_request")
Fixes: 978e51ba ("dm: optimize bio-based NVMe IO submission")
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 24113d4878439baf1f23c1a33dfcc340fba66e97 upstream.

Indirect calls are inefficient because of retpolines that are used for
spectre workaround. This patch replaces an indirect call with a condition
(that can be predicted by the branch predictor).
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit a1e1cb72d96491277ede8d257ce6b48a381dd336 upstream.

[Joseph: cherry-pick part_stat_get() from commit 1226b8dd0e91 ("block:
switch to per-cpu in-flight counters") since we don't want the whole
patch series get involved.]

The risk of redundant IO accounting was not taken into consideration
when commit 18a25da8 ("dm: ensure bio submission follows a
depth-first tree walk") introduced IO splitting in terms of recursion
via generic_make_request().

Fix this by subtracting the split bio's payload from the IO stats that
were already accounted for by start_io_acct() upon dm_make_request()
entry.  This repeat oscillation of the IO accounting, up then down,
isn't ideal but refactoring DM core's IO splitting to pre-split bios
_before_ they are accounted turned out to be an excessive amount of
change that will need a full development cycle to refine and verify.

Before this fix:

  /dev/mapper/stripe_dev is a 4-way stripe using a 32k chunksize, so
  bios are split on 32k boundaries.

  # fio --name=16M --filename=/dev/mapper/stripe_dev --rw=write --bs=64k --size=16M \
    	--iodepth=1 --ioengine=libaio --direct=1 --refill_buffers

  with debugging added:
  [103898.310264] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=0 len=128
  [103898.318704] device-mapper: core: __split_and_process_bio: recursing for following split bio:
  [103898.329136] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=64 len=64
  ...

  16M written yet 136M (278528 * 512b) accounted:
  # cat /sys/block/dm-2/stat | awk '{ print $7 }'
  278528

After this fix:

  16M written and 16M (32768 * 512b) accounted:
  # cat /sys/block/dm-2/stat | awk '{ print $7 }'
  32768

Fixes: 18a25da8 ("dm: ensure bio submission follows a depth-first tree walk")
Cc: stable@vger.kernel.org # 4.16+
Reported-by: NBryan Gurney <bgurney@redhat.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 57c36519e4b949f89381053f7283f5d605595b42 upstream.

DM's clone_bio() now benefits from using bio_trim() by fixing the fact
that clone_bio() wasn't clearing BIO_SEG_VALID like bio_trim() does;
which triggers blk_recount_segments() via bio_phys_segments().
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit a297b2fcee461e40df763e179cbbfba5a9e572d2 upstream.

In mpage_add_bh_to_extent(), when accumulated extents length is greater
than MAX_WRITEPAGES_EXTENT_LEN or buffer head's b_stat is not equal, we
will not continue to search unmapped area for this page, but note this
page is locked, and will only be unlocked in mpage_release_unused_pages()
after ext4_io_submit, if io also is throttled by blk-throttle or similar
io qos, we will hold this page locked for a while, it's unnecessary.

I think the best fix is to refactor mpage_add_bh_to_extent() to let it
return some hints whether to unlock this page, but given that we will
improve dioread_nolock later, we can let it done later, so currently
the simple fix would just call mpage_release_unused_pages() before
ext4_io_submit().
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>

Autogroup feature is used to improve interactivity for desktop
application. Since our kernel runs on server, just like RHEL8,
disable it by default to avoid unnecessary computing.

More details, please refer https://lwn.net/Articles/416641/Signed-off-by: NShanpei Chen <shanpeic@linux.alibaba.com>
Reviewed-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit df5ba5be7425e1df296d40c5f37a39d98ec666a2 upstream.

Pressure metrics are already recorded and exposed in procfs for the
entire system, but any tool which monitors cgroup pressure has to
special case the root cgroup to read from procfs.  This patch exposes
the already recorded pressure metrics on the root cgroup.

Link: http://lkml.kernel.org/r/20190510174938.3361741-1-dschatzberg@fb.comSigned-off-by: NDan Schatzberg <dschatzberg@fb.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 0e94682b73bfa6c44c98af7a26771c9c08c055d5 upstream.

Psi monitor aims to provide a low-latency short-term pressure detection
mechanism configurable by users.  It allows users to monitor psi metrics
growth and trigger events whenever a metric raises above user-defined
threshold within user-defined time window.

Time window and threshold are both expressed in usecs.  Multiple psi
resources with different thresholds and window sizes can be monitored
concurrently.

Psi monitors activate when system enters stall state for the monitored
psi metric and deactivate upon exit from the stall state.  While system
is in the stall state psi signal growth is monitored at a rate of 10
times per tracking window.  Min window size is 500ms, therefore the min
monitoring interval is 50ms.  Max window size is 10s with monitoring
interval of 1s.

When activated psi monitor stays active for at least the duration of one
tracking window to avoid repeated activations/deactivations when psi
signal is bouncing.

Notifications to the users are rate-limited to one per tracking window.

Link: http://lkml.kernel.org/r/20190319235619.260832-8-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit dc50537bdd1a0804fa2cbc990565ee9a944e66fa upstream.

Cgroup has a standardized poll/notification mechanism for waking all
pollers on all fds when a filesystem node changes.  To allow polling for
custom events, add a .poll callback that can override the default.

This is in preparation for pollable cgroup pressure files which have
per-fd trigger configurations.

Link: http://lkml.kernel.org/r/20190124211518.244221-3-surenb@google.comSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NSuren Baghdasaryan <surenb@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 147e1a97c4a0bdd43f55a582a9416bb9092563a9 upstream.

Patch series "psi: pressure stall monitors", v3.

Android is adopting psi to detect and remedy memory pressure that
results in stuttering and decreased responsiveness on mobile devices.

Psi gives us the stall information, but because we're dealing with
latencies in the millisecond range, periodically reading the pressure
files to detect stalls in a timely fashion is not feasible.  Psi also
doesn't aggregate its averages at a high enough frequency right now.

This patch series extends the psi interface such that users can
configure sensitive latency thresholds and use poll() and friends to be
notified when these are breached.

As high-frequency aggregation is costly, it implements an aggregation
method that is optimized for fast, short-interval averaging, and makes
the aggregation frequency adaptive, such that high-frequency updates
only happen while monitored stall events are actively occurring.

With these patches applied, Android can monitor for, and ward off,
mounting memory shortages before they cause problems for the user.  For
example, using memory stall monitors in userspace low memory killer
daemon (lmkd) we can detect mounting pressure and kill less important
processes before device becomes visibly sluggish.

In our memory stress testing psi memory monitors produce roughly 10x
less false positives compared to vmpressure signals.  Having ability to
specify multiple triggers for the same psi metric allows other parts of
Android framework to monitor memory state of the device and act
accordingly.

The new interface is straightforward.  The user opens one of the
pressure files for writing and writes a trigger description into the
file descriptor that defines the stall state - some or full, and the
maximum stall time over a given window of time.  E.g.:

        /* Signal when stall time exceeds 100ms of a 1s window */
        char trigger[] = "full 100000 1000000";
        fd = open("/proc/pressure/memory");
        write(fd, trigger, sizeof(trigger));
        while (poll() >= 0) {
                ...
        }
        close(fd);

When the monitored stall state is entered, psi adapts its aggregation
frequency according to what the configured time window requires in order
to emit event signals in a timely fashion.  Once the stalling subsides,
aggregation reverts back to normal.

The trigger is associated with the open file descriptor.  To stop
monitoring, the user only needs to close the file descriptor and the
trigger is discarded.

Patches 1-4 prepare the psi code for polling support.  Patch 5
implements the adaptive polling logic, the pressure growth detection
optimized for short intervals, and hooks up write() and poll() on the
pressure files.

The patches were developed in collaboration with Johannes Weiner.

This patch (of 5):

Kernfs has a standardized poll/notification mechanism for waking all
pollers on all fds when a filesystem node changes.  To allow polling for
custom events, add a .poll callback that can override the default.

This is in preparation for pollable cgroup pressure files which have
per-fd trigger configurations.

Link: http://lkml.kernel.org/r/20190124211518.244221-2-surenb@google.comSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NSuren Baghdasaryan <surenb@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 8af0c18af1425fc70686c0fdcfc0072cd8431aa0 upstream.

kthread.h can't be included in psi_types.h because it creates a circular
inclusion with kthread.h eventually including psi_types.h and
complaining on kthread structures not being defined because they are
defined further in the kthread.h.  Resolve this by removing psi_types.h
inclusion from the headers included from kthread.h.

Link: http://lkml.kernel.org/r/20190319235619.260832-7-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 333f3017c5a893b000b2b4a3529814ce93fa83d7 upstream.

Introduce changed_states parameter into collect_percpu_times to track
the states changed since the last update.

This will be needed to detect whether polled states activated in the
monitor patch.

Link: http://lkml.kernel.org/r/20190319235619.260832-6-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 7fc70a3999366560ad1d4f2389a78360300c2c6a upstream.

Split update_stats into collect_percpu_times and update_averages for
collect_percpu_times to be reused later inside psi monitor.

Link: http://lkml.kernel.org/r/20190319235619.260832-5-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit bcc78db64168eb6dede056fed2999f75f7ace309 upstream.

Rename psi_group structure member fields used for calculating psi totals
and averages for clear distinction between them and for trigger-related
fields that will be added by "psi: introduce psi monitor".

[surenb@google.com: v6]
  Link: http://lkml.kernel.org/r/20190319235619.260832-4-surenb@google.com
Link: http://lkml.kernel.org/r/20190124211518.244221-5-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 9289c5e6a78a5a9397df5fa60eb82b105abcfecf upstream.

psi_enable is not used outside of psi.c, make it static.

Link: http://lkml.kernel.org/r/20190319235619.260832-3-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
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>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 33b2d6302abc4ccea1d9b3f095e2e27b02ca264e upstream.

Patch series "psi: pressure stall monitors", v6.

This is a respin of:
  https://lwn.net/ml/linux-kernel/20190308184311.144521-1-surenb%40google.com/

Android is adopting psi to detect and remedy memory pressure that
results in stuttering and decreased responsiveness on mobile devices.

Psi gives us the stall information, but because we're dealing with
latencies in the millisecond range, periodically reading the pressure
files to detect stalls in a timely fashion is not feasible.  Psi also
doesn't aggregate its averages at a high-enough frequency right now.

This patch series extends the psi interface such that users can
configure sensitive latency thresholds and use poll() and friends to be
notified when these are breached.

As high-frequency aggregation is costly, it implements an aggregation
method that is optimized for fast, short-interval averaging, and makes
the aggregation frequency adaptive, such that high-frequency updates
only happen while monitored stall events are actively occurring.

With these patches applied, Android can monitor for, and ward off,
mounting memory shortages before they cause problems for the user.  For
example, using memory stall monitors in userspace low memory killer
daemon (lmkd) we can detect mounting pressure and kill less important
processes before device becomes visibly sluggish.  In our memory stress
testing psi memory monitors produce roughly 10x less false positives
compared to vmpressure signals.  Having ability to specify multiple
triggers for the same psi metric allows other parts of Android framework
to monitor memory state of the device and act accordingly.

The new interface is straight-forward.  The user opens one of the
pressure files for writing and writes a trigger description into the
file descriptor that defines the stall state - some or full, and the
maximum stall time over a given window of time.  E.g.:

        /* Signal when stall time exceeds 100ms of a 1s window */
        char trigger[] = "full 100000 1000000"
        fd = open("/proc/pressure/memory")
        write(fd, trigger, sizeof(trigger))
        while (poll() >= 0) {
                ...
        };
        close(fd);

When the monitored stall state is entered, psi adapts its aggregation
frequency according to what the configured time window requires in order
to emit event signals in a timely fashion.  Once the stalling subsides,
aggregation reverts back to normal.

The trigger is associated with the open file descriptor.  To stop
monitoring, the user only needs to close the file descriptor and the
trigger is discarded.

Patches 1-6 prepare the psi code for polling support.  Patch 7
implements the adaptive polling logic, the pressure growth detection
optimized for short intervals, and hooks up write() and poll() on the
pressure files.

The patches were developed in collaboration with Johannes Weiner.

This patch (of 7):

The psi monitoring patches will need to determine the same states as
record_times().  To avoid calculating them twice, maintain a state mask
that can be consulted cheaply.  Do this in a separate patch to keep the
churn in the main feature patch at a minimum.

This adds 4-byte state_mask member into psi_group_cpu struct which
results in its first cacheline-aligned part becoming 52 bytes long.  Add
explicit values to enumeration element counters that affect
psi_group_cpu struct size.

Link: http://lkml.kernel.org/r/20190124211518.244221-4-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit be87ab0afd680ac35486d16c0963c56d9be1d8a0 upstream.

The output of the PSI files show a bunch of numbers with no unit.  The
psi.txt documentation file also does not indicate what units are used.
One can only find out by looking at the source code.  The units are
percentage for the averages and useconds for the total.  Make the
information easier to find by documenting the units in psi.txt.

Link: http://lkml.kernel.org/r/20190402193810.3450-1-longman@redhat.comSigned-off-by: NWaiman Long <longman@redhat.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 4e37504d1c49eec6434d0cc97278d2b51c9e8763 upstream.

We've been seeing hard-to-trigger psi crashes when running inside VM
instances:

    divide error: 0000 [#1] SMP PTI
    Modules linked in: [...]
    CPU: 0 PID: 212 Comm: kworker/0:2 Not tainted 4.16.18-119_fbk9_3817_gfe944c98d695 #119
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
    Workqueue: events psi_clock
    RIP: 0010:psi_update_stats+0x270/0x490
    RSP: 0018:ffffc90001117e10 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8800a35a13f8
    RDX: 0000000000000000 RSI: ffff8800a35a1340 RDI: 0000000000000000
    RBP: 0000000000000658 R08: ffff8800a35a1470 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
    R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000f8502
    FS:  0000000000000000(0000) GS:ffff88023fc00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007fbe370fa000 CR3: 00000000b1e3a000 CR4: 00000000000006f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     psi_clock+0x12/0x50
     process_one_work+0x1e0/0x390
     worker_thread+0x2b/0x3c0
     ? rescuer_thread+0x330/0x330
     kthread+0x113/0x130
     ? kthread_create_worker_on_cpu+0x40/0x40
     ? SyS_exit_group+0x10/0x10
     ret_from_fork+0x35/0x40
    Code: 48 0f 47 c7 48 01 c2 45 85 e4 48 89 16 0f 85 e6 00 00 00 4c 8b 49 10 4c 8b 51 08 49 69 d9 f2 07 00 00 48 6b c0 64 4c 8b 29 31 d2 <48> f7 f7 49 69 d5 8d 06 00 00 48 89 c5 4c 69 f0 00 98 0b 00 48

The Code-line points to `period` being 0 inside update_stats(), and we
divide by that when calculating that period's pressure percentage.

The elapsed period should never be 0.  The reason this can happen is due
to an off-by-one in the idle time / missing period calculation combined
with a coarse sched_clock() in the virtual machine.

The target time for aggregation is advanced into the future on a fixed
grid to prevent clock drift.  So when an aggregation runs after some idle
period, we can not just set it to "now + psi_period", but have to
calculate the downtime and advance the target time relative to itself.

However, if the aggregator was disabled exactly one psi_period (ns), we
drop one idle period in the calculation due to a > when we should do >=.
In that case, next_update will be advanced from 'now - psi_period' to
'now' when it should be moved to 'now + psi_period'.  The run finishes
with last_update == next_update == sched_clock().

With hardware clocks, this exact nanosecond match isn't likely in the
first place; but if it does happen, the clock will still have moved on and
the period non-zero by the time the worker runs.  A pointlessly short
period, but besides the extra work, no harm no foul.  However, a slow
sched_clock() like we have on VMs might not have advanced either by the
time the worker runs again.  And when we calculate the elapsed period, the
result, our pressure divisor, will be 0.  Ouch.

Fix this by correctly handling the situation when the elapsed time between
aggregation runs is precisely two periods, and advance the expiration
timestamp correctly to period into the future.

Link: http://lkml.kernel.org/r/20190214193157.15788-1-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reported-by: Łukasz Siudut <lsiudut@fb.com
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 7b2489d37e1e355228f7c55724f77580e1dec22a upstream.

The current help text caused some confusion in online forums about
whether or not to default-enable or default-disable psi in vendor
kernels.  This is because it doesn't communicate the reason for why we
made this setting configurable in the first place: that the overhead is
non-zero in an artificial scheduler stress test.

Since this isn't representative of real workloads, and the effect was
not measurable in scheduler-heavy real world applications such as the
webservers and memcache installations at Facebook, it's fair to point
out that this is a pretty cautious option to select.

Link: http://lkml.kernel.org/r/20190129233617.16767-1-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 1b69ac6b40ebd85eed73e4dbccde2a36961ab990 upstream.

psi has provisions to shut off the periodic aggregation worker when
there is a period of no task activity - and thus no data that needs
aggregating.  However, while developing psi monitoring, Suren noticed
that the aggregation clock currently won't stay shut off for good.

Debugging this revealed a flaw in the idle design: an aggregation run
will see no task activity and decide to go to sleep; shortly thereafter,
the kworker thread that executed the aggregation will go idle and cause
a scheduling change, during which the psi callback will kick the
!pending worker again.  This will ping-pong forever, and is equivalent
to having no shut-off logic at all (but with more code!)

Fix this by exempting aggregation workers from psi's clock waking logic
when the state change is them going to sleep.  To do this, tag workers
with the last work function they executed, and if in psi we see a worker
going to sleep after aggregating psi data, we will not reschedule the
aggregation work item.

What if the worker is also executing other items before or after?

Any psi state times that were incurred by work items preceding the
aggregation work will have been collected from the per-cpu buckets
during the aggregation itself.  If there are work items following the
aggregation work, the worker's last_func tag will be overwritten and the
aggregator will be kept alive to process this genuine new activity.

If the aggregation work is the last thing the worker does, and we decide
to go idle, the brief period of non-idle time incurred between the
aggregation run and the kworker's dequeue will be stranded in the
per-cpu buckets until the clock is woken by later activity.  But that
should not be a problem.  The buckets can hold 4s worth of time, and
future activity will wake the clock with a 2s delay, giving us 2s worth
of data we can leave behind when disabling aggregation.  If it takes a
worker more than two seconds to go idle after it finishes its last work
item, we likely have bigger problems in the system, and won't notice one
sample that was averaged with a bogus per-CPU weight.

Link: http://lkml.kernel.org/r/20190116193501.1910-1-hannes@cmpxchg.org
Fixes: eb414681d5a0 ("psi: pressure stall information for CPU, memory, and IO")
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reported-by: NSuren Baghdasaryan <surenb@google.com>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 428a1cb4baeb9e5c7feda93af7372ba6d2491558 upstream.

The kernel commandline parameter named in CONFIG_PSI_DEFAULT_DISABLED
help text contradicts the documentation in kernel-parameters.txt, and
the code.  Fix that.

Link: http://lkml.kernel.org/r/20181203213416.GA12627@cmpxchg.org
Fixes: e0c274472d ("psi: make disabling/enabling easier for vendor kernels")
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
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>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit e0c274472d5d27f277af722e017525e0b33784cd upstream.

Mel Gorman reports a hackbench regression with psi that would prohibit
shipping the suse kernel with it default-enabled, but he'd still like
users to be able to opt in at little to no cost to others.

With the current combination of CONFIG_PSI and the psi_disabled bool set
from the commandline, this is a challenge.  Do the following things to
make it easier:

1. Add a config option CONFIG_PSI_DEFAULT_DISABLED that allows distros
   to enable CONFIG_PSI in their kernel but leave the feature disabled
   unless a user requests it at boot-time.

   To avoid double negatives, rename psi_disabled= to psi=.

2. Make psi_disabled a static branch to eliminate any branch costs
   when the feature is disabled.

In terms of numbers before and after this patch, Mel says:

: The following is a comparision using CONFIG_PSI=n as a baseline against
: your patch and a vanilla kernel
:
:                          4.20.0-rc4             4.20.0-rc4             4.20.0-rc4
:                 kconfigdisable-v1r1                vanilla        psidisable-v1r1
: Amean     1       1.3100 (   0.00%)      1.3923 (  -6.28%)      1.3427 (  -2.49%)
: Amean     3       3.8860 (   0.00%)      4.1230 *  -6.10%*      3.8860 (  -0.00%)
: Amean     5       6.8847 (   0.00%)      8.0390 * -16.77%*      6.7727 (   1.63%)
: Amean     7       9.9310 (   0.00%)     10.8367 *  -9.12%*      9.9910 (  -0.60%)
: Amean     12     16.6577 (   0.00%)     18.2363 *  -9.48%*     17.1083 (  -2.71%)
: Amean     18     26.5133 (   0.00%)     27.8833 *  -5.17%*     25.7663 (   2.82%)
: Amean     24     34.3003 (   0.00%)     34.6830 (  -1.12%)     32.0450 (   6.58%)
: Amean     30     40.0063 (   0.00%)     40.5800 (  -1.43%)     41.5087 (  -3.76%)
: Amean     32     40.1407 (   0.00%)     41.2273 (  -2.71%)     39.9417 (   0.50%)
:
: It's showing that the vanilla kernel takes a hit (as the bisection
: indicated it would) and that disabling PSI by default is reasonably
: close in terms of performance for this particular workload on this
: particular machine so;

Link: http://lkml.kernel.org/r/20181127165329.GA29728@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Tested-by: NMel Gorman <mgorman@techsingularity.net>
Reported-by: NMel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 8fcb2312d1e3300e81aa871aad00d4c038cfc184 upstream.

The existing code triggered an invalid warning about 'rq' possibly being
used uninitialized.  Instead of doing the silly warning suppression by
initializa it to NULL, refactor the code to bail out early instead.

Warning was:

  kernel/sched/psi.c: In function `cgroup_move_task':
  kernel/sched/psi.c:639:13: warning: `rq' may be used uninitialized in this function [-Wmaybe-uninitialized]

Link: http://lkml.kernel.org/r/20181103183339.8669-1-olof@lixom.net
Fixes: 2ce7135adc9ad ("psi: cgroup support")
Signed-off-by: NOlof Johansson <olof@lixom.net>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 2ce7135adc9ad081aa3c49744144376ac74fea60 upstream.

On a system that executes multiple cgrouped jobs and independent
workloads, we don't just care about the health of the overall system, but
also that of individual jobs, so that we can ensure individual job health,
fairness between jobs, or prioritize some jobs over others.

This patch implements pressure stall tracking for cgroups.  In kernels
with CONFIG_PSI=y, cgroup2 groups will have cpu.pressure, memory.pressure,
and io.pressure files that track aggregate pressure stall times for only
the tasks inside the cgroup.

Link: http://lkml.kernel.org/r/20180828172258.3185-10-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NDaniel Drake <drake@endlessm.com>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
[Joseph: fix apply conflicts in cgroup_create()]
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

Conflicts:
    kernel/cgroup/cgroup.c

commit eb414681d5a07d28d2ff90dc05f69ec6b232ebd2 upstream.

When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills.  In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.

In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.

A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively.  Stall states are aggregate versions of the per-task delay
accounting delays:

       cpu: some tasks are runnable but not executing on a CPU
       memory: tasks are reclaiming, or waiting for swapin or thrashing cache
       io: tasks are waiting for io completions

These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit.  They can also indicate when the system
is approaching lockup scenarios and OOMs.

To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states.  Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime.  A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).

[hannes@cmpxchg.org: doc fixlet, per Randy]
  Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
  Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
  Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
  Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NDaniel Drake <drake@endlessm.com>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
[Joseph: fix apply conflicts in task_struct]
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 246b3b3342c9b0a2e24cda2178be87bc36e1c874 upstream.

do_sched_yield() disables IRQs, looks up this_rq() and locks it.  The next
patch is adding another site with the same pattern, so provide a
convenience function for it.

Link: http://lkml.kernel.org/r/20180828172258.3185-8-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Tested-by: NDaniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 1f351d7f7590857ea281579c26e6045b4c548ef4 upstream.

kernel/sched/sched.h includes "stats.h" half-way through the file.  The
next patch introduces users of sched.h's rq locking functions and
update_rq_clock() in kernel/sched/stats.h.  Move those definitions up in
the file so they are available in stats.h.

Link: http://lkml.kernel.org/r/20180828172258.3185-7-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Tested-by: NDaniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 5c54f5b9edb1aa2eabbb1091c458f1b6776a1896 upstream.

It's going to be used in a later patch. Keep the churn separate.

Link: http://lkml.kernel.org/r/20180828172258.3185-6-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Tested-by: NDaniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

commit 8508cf3ffad4defa202b303e5b6379efc4cd9054 upstream.

There are several definitions of those functions/macros in places that
mess with fixed-point load averages.  Provide an official version.

[akpm@linux-foundation.org: fix missed conversion in block/blk-iolatency.c]
Link: http://lkml.kernel.org/r/20180828172258.3185-5-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NSuren Baghdasaryan <surenb@google.com>
Tested-by: NDaniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
[Joseph: use stat.mean instead of stat->rqs.mean to solve conflict]
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

Conflicts:
    block/blk-iolatency.c