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  1. 08 8月, 2019 9 次提交
    • P
      sched/fair: Expose newidle_balance() · 5ba553ef
      由 Peter Zijlstra 提交于 
      For pick_next_task_fair() it is the newidle balance that requires
dropping the rq->lock; provided we do put_prev_task() early, we can
also detect the condition for doing newidle early.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/9e3eb1859b946f03d7e500453a885725b68957ba.1559129225.git.vpillai@digitalocean.com
      5ba553ef
    • P
      sched: Add task_struct pointer to sched_class::set_curr_task · 03b7fad1
      由 Peter Zijlstra 提交于 
      In preparation of further separating pick_next_task() and
set_curr_task() we have to pass the actual task into it, while there,
rename the thing to better pair with put_prev_task().
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/a96d1bcdd716db4a4c5da2fece647a1456c0ed78.1559129225.git.vpillai@digitalocean.com
      03b7fad1
    • P
      sched: Rework CPU hotplug task selection · 10e7071b
      由 Peter Zijlstra 提交于 
      The CPU hotplug task selection is the only place where we used
put_prev_task() on a task that is not current. While looking at that,
it occured to me that we can simplify all that by by using a custom
pick loop.

Since we don't need to put current, we can do away with the fake task
too.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
      10e7071b
    • P
      sched/{rt,deadline}: Fix set_next_task vs pick_next_task · f95d4eae
      由 Peter Zijlstra 提交于 
      Because pick_next_task() implies set_curr_task() and some of the
details haven't mattered too much, some of what _should_ be in
set_curr_task() ended up in pick_next_task, correct this.

This prepares the way for a pick_next_task() variant that does not
affect the current state; allowing remote picking.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/38c61d5240553e043c27c5e00b9dd0d184dd6081.1559129225.git.vpillai@digitalocean.com
      f95d4eae
    • P
      sched: Fix kerneldoc comment for ia64_set_curr_task · 5feeb783
      由 Peter Zijlstra 提交于 
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/fde3a65ea3091ec6b84dac3c19639f85f452c5d1.1559129225.git.vpillai@digitalocean.com
      5feeb783
    • P
      stop_machine: Fix stop_cpus_in_progress ordering · 99d84bf8
      由 Peter Zijlstra 提交于 
      Make sure the entire for loop has stop_cpus_in_progress set.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/0fd8fd4b99b9b9aa88d8b2dff897f7fd0d88f72c.1559129225.git.vpillai@digitalocean.com
      99d84bf8
    • D
      sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices · de53fd7a
      由 Dave Chiluk 提交于 
      It has been observed, that highly-threaded, non-cpu-bound applications
running under cpu.cfs_quota_us constraints can hit a high percentage of
periods throttled while simultaneously not consuming the allocated
amount of quota. This use case is typical of user-interactive non-cpu
bound applications, such as those running in kubernetes or mesos when
run on multiple cpu cores.

This has been root caused to cpu-local run queue being allocated per cpu
bandwidth slices, and then not fully using that slice within the period.
At which point the slice and quota expires. This expiration of unused
slice results in applications not being able to utilize the quota for
which they are allocated.

The non-expiration of per-cpu slices was recently fixed by
'commit 512ac999 ("sched/fair: Fix bandwidth timer clock drift
condition")'. Prior to that it appears that this had been broken since
at least 'commit 51f2176d ("sched/fair: Fix unlocked reads of some
cfs_b->quota/period")' which was introduced in v3.16-rc1 in 2014. That
added the following conditional which resulted in slices never being
expired.

if (cfs_rq->runtime_expires != cfs_b->runtime_expires) {
	/* extend local deadline, drift is bounded above by 2 ticks */
	cfs_rq->runtime_expires += TICK_NSEC;

Because this was broken for nearly 5 years, and has recently been fixed
and is now being noticed by many users running kubernetes
(https://github.com/kubernetes/kubernetes/issues/67577) it is my opinion
that the mechanisms around expiring runtime should be removed
altogether.

This allows quota already allocated to per-cpu run-queues to live longer
than the period boundary. This allows threads on runqueues that do not
use much CPU to continue to use their remaining slice over a longer
period of time than cpu.cfs_period_us. However, this helps prevent the
above condition of hitting throttling while also not fully utilizing
your cpu quota.

This theoretically allows a machine to use slightly more than its
allotted quota in some periods. This overflow would be bounded by the
remaining quota left on each per-cpu runqueueu. This is typically no
more than min_cfs_rq_runtime=1ms per cpu. For CPU bound tasks this will
change nothing, as they should theoretically fully utilize all of their
quota in each period. For user-interactive tasks as described above this
provides a much better user/application experience as their cpu
utilization will more closely match the amount they requested when they
hit throttling. This means that cpu limits no longer strictly apply per
period for non-cpu bound applications, but that they are still accurate
over longer timeframes.

This greatly improves performance of high-thread-count, non-cpu bound
applications with low cfs_quota_us allocation on high-core-count
machines. In the case of an artificial testcase (10ms/100ms of quota on
80 CPU machine), this commit resulted in almost 30x performance
improvement, while still maintaining correct cpu quota restrictions.
That testcase is available at https://github.com/indeedeng/fibtest.

Fixes: 512ac999 ("sched/fair: Fix bandwidth timer clock drift condition")
Signed-off-by: NDave Chiluk <chiluk+linux@indeed.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NPhil Auld <pauld@redhat.com>
Reviewed-by: NBen Segall <bsegall@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Hammond <jhammond@indeed.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kyle Anderson <kwa@yelp.com>
Cc: Gabriel Munos <gmunoz@netflix.com>
Cc: Peter Oskolkov <posk@posk.io>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Brendan Gregg <bgregg@netflix.com>
Link: https://lkml.kernel.org/r/1563900266-19734-2-git-send-email-chiluk+linux@indeed.com
      de53fd7a
    • P
      sched: Clean up active_mm reference counting · 139d025c
      由 Peter Zijlstra 提交于 
      The current active_mm reference counting is confusing and sub-optimal.

Rewrite the code to explicitly consider the 4 separate cases:

    user -> user

	When switching between two user tasks, all we need to consider
	is switch_mm().

    user -> kernel

	When switching from a user task to a kernel task (which
	doesn't have an associated mm) we retain the last mm in our
	active_mm. Increment a reference count on active_mm.

  kernel -> kernel

	When switching between kernel threads, all we need to do is
	pass along the active_mm reference.

  kernel -> user

	When switching between a kernel and user task, we must switch
	from the last active_mm to the next mm, hoping of course that
	these are the same. Decrement a reference on the active_mm.

The code keeps a different order, because as you'll note, both 'to
user' cases require switch_mm().

And where the old code would increment/decrement for the 'kernel ->
kernel' case, the new code observes this is a neutral operation and
avoids touching the reference count.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NRik van Riel <riel@surriel.com>
Reviewed-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: luto@kernel.org
      139d025c
    • P
      rcu/tree: Fix SCHED_FIFO params · 130d9c33
      由 Peter Zijlstra 提交于 
      A rather embarrasing mistake had us call sched_setscheduler() before
initializing the parameters passed to it.

Fixes: 1a763fd7 ("rcu/tree: Call setschedule() gp ktread to SCHED_FIFO outside of atomic region")
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NPaul E. McKenney <paulmck@linux.ibm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
      130d9c33
  3. 25 7月, 2019 23 次提交
  5. 23 7月, 2019 5 次提交
  7. 22 7月, 2019 3 次提交
    • L
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 83768245
      由 Linus Torvalds 提交于 
      Pull networking fixes from David Miller:

 1) Several netfilter fixes including a nfnetlink deadlock fix from
    Florian Westphal and fix for dropping VRF packets from Miaohe Lin.

 2) Flow offload fixes from Pablo Neira Ayuso including a fix to restore
    proper block sharing.

 3) Fix r8169 PHY init from Thomas Voegtle.

 4) Fix memory leak in mac80211, from Lorenzo Bianconi.

 5) Missing NULL check on object allocation in cxgb4, from Navid
    Emamdoost.

 6) Fix scaling of RX power in sfp phy driver, from Andrew Lunn.

 7) Check that there is actually an ip header to access in skb->data in
    VRF, from Peter Kosyh.

 8) Remove spurious rcu unlock in hv_netvsc, from Haiyang Zhang.

 9) One more tweak the the TCP fragmentation memory limit changes, to be
    less harmful to applications setting small SO_SNDBUF values. From
    Eric Dumazet.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (40 commits)
  tcp: be more careful in tcp_fragment()
  hv_netvsc: Fix extra rcu_read_unlock in netvsc_recv_callback()
  vrf: make sure skb->data contains ip header to make routing
  connector: remove redundant input callback from cn_dev
  qed: Prefer pcie_capability_read_word()
  igc: Prefer pcie_capability_read_word()
  cxgb4: Prefer pcie_capability_read_word()
  be2net: Synchronize be_update_queues with dev_watchdog
  bnx2x: Prevent load reordering in tx completion processing
  net: phy: sfp: hwmon: Fix scaling of RX power
  net: sched: verify that q!=NULL before setting q->flags
  chelsio: Fix a typo in a function name
  allocate_flower_entry: should check for null deref
  net: hns3: typo in the name of a constant
  kbuild: add net/netfilter/nf_tables_offload.h to header-test blacklist.
  tipc: Fix a typo
  mac80211: don't warn about CW params when not using them
  mac80211: fix possible memory leak in ieee80211_assign_beacon
  nl80211: fix NL80211_HE_MAX_CAPABILITY_LEN
  nl80211: fix VENDOR_CMD_RAW_DATA
  ...
      83768245
    • S
      pidfd: fix a poll race when setting exit_state · b191d649
      由 Suren Baghdasaryan 提交于 
      There is a race between reading task->exit_state in pidfd_poll and
writing it after do_notify_parent calls do_notify_pidfd. Expected
sequence of events is:

CPU 0                            CPU 1
------------------------------------------------
exit_notify
  do_notify_parent
    do_notify_pidfd
  tsk->exit_state = EXIT_DEAD
                                  pidfd_poll
                                     if (tsk->exit_state)

However nothing prevents the following sequence:

CPU 0                            CPU 1
------------------------------------------------
exit_notify
  do_notify_parent
    do_notify_pidfd
                                   pidfd_poll
                                      if (tsk->exit_state)
  tsk->exit_state = EXIT_DEAD

This causes a polling task to wait forever, since poll blocks because
exit_state is 0 and the waiting task is not notified again. A stress
test continuously doing pidfd poll and process exits uncovered this bug.

To fix it, we make sure that the task's exit_state is always set before
calling do_notify_pidfd.

Fixes: b53b0b9d ("pidfd: add polling support")
Cc: kernel-team@android.com
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NSuren Baghdasaryan <surenb@google.com>
Signed-off-by: NJoel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20190717172100.261204-1-joel@joelfernandes.org
[christian@brauner.io: adapt commit message and drop unneeded changes from wait_task_zombie]
Signed-off-by: NChristian Brauner <christian@brauner.io>
      b191d649
    • E
      tcp: be more careful in tcp_fragment() · b617158d
      由 Eric Dumazet 提交于 
      Some applications set tiny SO_SNDBUF values and expect
TCP to just work. Recent patches to address CVE-2019-11478
broke them in case of losses, since retransmits might
be prevented.

We should allow these flows to make progress.

This patch allows the first and last skb in retransmit queue
to be split even if memory limits are hit.

It also adds the some room due to the fact that tcp_sendmsg()
and tcp_sendpage() might overshoot sk_wmem_queued by about one full
TSO skb (64KB size). Note this allowance was already present
in stable backports for kernels < 4.15

Note for < 4.15 backports :
 tcp_rtx_queue_tail() will probably look like :

static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
{
	struct sk_buff *skb = tcp_send_head(sk);

	return skb ? tcp_write_queue_prev(sk, skb) : tcp_write_queue_tail(sk);
}

Fixes: f070ef2a ("tcp: tcp_fragment() should apply sane memory limits")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: NAndrew Prout <aprout@ll.mit.edu>
Tested-by: NAndrew Prout <aprout@ll.mit.edu>
Tested-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Tested-by: NMichal Kubecek <mkubecek@suse.cz>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Acked-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NChristoph Paasch <cpaasch@apple.com>
Cc: Jonathan Looney <jtl@netflix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b617158d