This reverts commits 0a4e6be9ca17c54817cf814b4b5aa60478c6df27
and 80f7fdb1c7f0f9266421f823964fd1962681f6ce.

The task migration notifier was originally introduced in order to support
the pvclock vsyscall with non-synchronized TSC, but KVM only supports it
with synchronized TSC.  Hence, on KVM the race condition is only needed
due to a bad implementation on the host side, and even then it's so rare
that it's mostly theoretical.

As far as KVM is concerned it's possible to fix the host, avoiding the
additional complexity in the vDSO and the (re)introduction of the task
migration notifier.

Xen, on the other hand, hasn't yet implemented vsyscall support at
all, so we do not care about its plans for non-synchronized TSC.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull NOHZ changes from Ingo Molnar:
 "This tree adds full dynticks support to KVM guests (support the
  disabling of the timer tick on the guest).  The main missing piece was
  the recognition of guest execution as RCU extended quiescent state and
  related changes"

* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest
  context_tracking: Export context_tracking_user_enter/exit
  context_tracking: Run vtime_user_enter/exit only when state == CONTEXT_USER
  context_tracking: Add stub context_tracking_is_enabled
  context_tracking: Generalize context tracking APIs to support user and guest
  context_tracking: Rename context symbols to prepare for transition state
  ppc: Remove unused cpp symbols in kvm headers

Pull cgroup updates from Tejun Heo:
 "Nothing too interesting.  Rik made cpuset cooperate better with
  isolcpus and there are several other cleanup patches"

* 'for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset, isolcpus: document relationship between cpusets & isolcpus
  cpusets, isolcpus: exclude isolcpus from load balancing in cpusets
  sched, isolcpu: make cpu_isolated_map visible outside scheduler
  cpuset: initialize cpuset a bit early
  cgroup: Use kvfree in pidlist_free()
  cgroup: call cgroup_subsys->bind on cgroup subsys initialization

Pull scheduler changes from Ingo Molnar:
 "Major changes:

   - Reworked CPU capacity code, for better SMP load balancing on
     systems with assymetric CPUs. (Vincent Guittot, Morten Rasmussen)

   - Reworked RT task SMP balancing to be push based instead of pull
     based, to reduce latencies on large CPU count systems. (Steven
     Rostedt)

   - SCHED_DEADLINE support updates and fixes. (Juri Lelli)

   - SCHED_DEADLINE task migration support during CPU hotplug. (Wanpeng Li)

   - x86 mwait-idle optimizations and fixes. (Mike Galbraith, Len Brown)

   - sched/numa improvements. (Rik van Riel)

   - various cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits)
  sched/core: Drop debugging leftover trace_printk call
  sched/deadline: Support DL task migration during CPU hotplug
  sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()
  sched/deadline: Always enqueue on previous rq when dl_task_timer() fires
  sched/core: Remove unused argument from init_[rt|dl]_rq()
  sched/deadline: Fix rt runtime corruption when dl fails its global constraints
  sched/deadline: Avoid a superfluous check
  sched: Improve load balancing in the presence of idle CPUs
  sched: Optimize freq invariant accounting
  sched: Move CFS tasks to CPUs with higher capacity
  sched: Add SD_PREFER_SIBLING for SMT level
  sched: Remove unused struct sched_group_capacity::capacity_orig
  sched: Replace capacity_factor by usage
  sched: Calculate CPU's usage statistic and put it into struct sg_lb_stats::group_usage
  sched: Add struct rq::cpu_capacity_orig
  sched: Make scale_rt invariant with frequency
  sched: Make sched entity usage tracking scale-invariant
  sched: Remove frequency scaling from cpu_capacity
  sched: Track group sched_entity usage contributions
  sched: Add sched_avg::utilization_avg_contrib
  ...

Pull KVM updates from Paolo Bonzini:
 "First batch of KVM changes for 4.1

  The most interesting bit here is irqfd/ioeventfd support for ARM and
  ARM64.

  Summary:

  ARM/ARM64:
     fixes for live migration, irqfd and ioeventfd support (enabling
     vhost, too), page aging

  s390:
     interrupt handling rework, allowing to inject all local interrupts
     via new ioctl and to get/set the full local irq state for migration
     and introspection.  New ioctls to access memory by virtual address,
     and to get/set the guest storage keys.  SIMD support.

  MIPS:
     FPU and MIPS SIMD Architecture (MSA) support.  Includes some
     patches from Ralf Baechle's MIPS tree.

  x86:
     bugfixes (notably for pvclock, the others are small) and cleanups.
     Another small latency improvement for the TSC deadline timer"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (146 commits)
  KVM: use slowpath for cross page cached accesses
  kvm: mmu: lazy collapse small sptes into large sptes
  KVM: x86: Clear CR2 on VCPU reset
  KVM: x86: DR0-DR3 are not clear on reset
  KVM: x86: BSP in MSR_IA32_APICBASE is writable
  KVM: x86: simplify kvm_apic_map
  KVM: x86: avoid logical_map when it is invalid
  KVM: x86: fix mixed APIC mode broadcast
  KVM: x86: use MDA for interrupt matching
  kvm/ppc/mpic: drop unused IRQ_testbit
  KVM: nVMX: remove unnecessary double caching of MAXPHYADDR
  KVM: nVMX: checks for address bits beyond MAXPHYADDR on VM-entry
  KVM: x86: cache maxphyaddr CPUID leaf in struct kvm_vcpu
  KVM: vmx: pass error code with internal error #2
  x86: vdso: fix pvclock races with task migration
  KVM: remove kvm_read_hva and kvm_read_hva_atomic
  KVM: x86: optimize delivery of TSC deadline timer interrupt
  KVM: x86: extract blocking logic from __vcpu_run
  kvm: x86: fix x86 eflags fixed bit
  KVM: s390: migrate vcpu interrupt state
  ...

Commit:

  3c18d447b3b3 ("sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()")

forgot a trace_printk() debugging piece in and Steve's banner screamed
in dmesg. Remove it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1428050570-21041-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Hotplug operations are destructive w.r.t. cpusets. In case such an
operation is performed on a CPU belonging to an exlusive cpuset, the
DL bandwidth information associated with the corresponding root
domain is gone even if the operation fails (in sched_cpu_inactive()).

For this reason we need to move the check we currently have in
sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless
cpusets reconfiguration in the CPU_DOWN_FAILED path.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Link: http://lkml.kernel.org/r/1427792017-7356-2-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Obviously, 'rq' is not used in these two functions, therefore,
there is no reason for it to be passed as an argument.

Signed-off-by: Abel Vesa <abelvesa@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1425383427-26244-1-git-send-email-abelvesa@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

One version of sched_rt_global_constaints() (the !rt-cgroup one)
changes state, therefore if we fail the later sched_dl_global_constraints()
call the state is left in an inconsistent state.

Fix this by changing the order of the calls.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
[ Improved the changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Link: http://lkml.kernel.org/r/1426590931-4639-2-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Add the SD_PREFER_SIBLING flag for SMT level in order to ensure that
the scheduler will place at least one task per core.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: Morten.Rasmussen@arm.com
Cc: dietmar.eggemann@arm.com
Cc: efault@gmx.de
Cc: kamalesh@linux.vnet.ibm.com
Cc: linaro-kernel@lists.linaro.org
Cc: nicolas.pitre@linaro.org
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1425052454-25797-11-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>