linux.git, branch v4.12.4

Linux 4.12.4

2017-07-27T22:10:39+00:00

sched/cputime: Don't use smp_processor_id() in preemptible context

2017-07-27T22:10:25+00:00

commit 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 upstream.

Recent kernels trigger this warning:

 BUG: using smp_processor_id() in preemptible [00000000] code: 99-trinity/181
 caller is debug_smp_processor_id+0x17/0x19
 CPU: 0 PID: 181 Comm: 99-trinity Not tainted 4.12.0-01059-g2a42eb9 #1
 Call Trace:
  dump_stack+0x82/0xb8
  check_preemption_disabled()
  debug_smp_processor_id()
  vtime_delta()
  task_cputime()
  thread_group_cputime()
  thread_group_cputime_adjusted()
  wait_consider_task()
  do_wait()
  SYSC_wait4()
  do_syscall_64()
  entry_SYSCALL64_slow_path()

As Frederic pointed out:

| Although those sched_clock_cpu() things seem to only matter when the
| sched_clock() is unstable. And that stability is a condition for nohz_full
| to work anyway. So probably sched_clock() alone would be enough.

This patch fixes it by replacing sched_clock_cpu() with sched_clock() to
avoid calling smp_processor_id() in a preemptible context.

Reported-by: Xiaolong Ye 
Signed-off-by: Wanpeng Li 
Cc: Frederic Weisbecker 
Cc: Linus Torvalds 
Cc: Luiz Capitulino 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com
[ Prettified the changelog. ]
Signed-off-by: Ingo Molnar 
Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman

alarmtimer: don't rate limit one-shot timers

2017-07-27T22:10:25+00:00

Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a
minimum bound on the alarm timer interval.  This minimum bound shouldn't
be applied if the interval is 0.  Otherwise, one-shot timers will be
converted into periodic ones.

This patch is specific to 4.11.y and 4.12.y.  Older -stable trees have a
slightly different patch, and 4.13-rc2 isn't impacted due to a later
refactoring.

Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals")
Reported-by: Ben Fennema 
Signed-off-by: Greg Hackmann 
Cc: John Stultz 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

smp/hotplug: Replace BUG_ON and react useful

2017-07-27T22:10:25+00:00

commit dea1d0f5f1284e3defee4b8484d9fc230686cd42 upstream.

The move of the unpark functions to the control thread moved the BUG_ON()
there as well. While it made some sense in the idle thread of the upcoming
CPU, it's bogus to crash the control thread on the already online CPU,
especially as the function has a return value and the callsite is prepared
to handle an error return.

Replace it with a WARN_ON_ONCE() and return a proper error code.

Fixes: 9cd4f1a4e7a8 ("smp/hotplug: Move unparking of percpu threads to the control CPU")
Rightfully-ranted-at-by: Linux Torvalds 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

smp/hotplug: Move unparking of percpu threads to the control CPU

2017-07-27T22:10:24+00:00

commit 9cd4f1a4e7a858849e889a081a99adff83e08e4c upstream.

Vikram reported the following backtrace:

   BUG: scheduling while atomic: swapper/7/0/0x00000002
   CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.32-perf+ #680
   schedule
   schedule_hrtimeout_range_clock
   schedule_hrtimeout
   wait_task_inactive
   __kthread_bind_mask
   __kthread_bind
   __kthread_unpark
   kthread_unpark
   cpuhp_online_idle
   cpu_startup_entry
   secondary_start_kernel

He analyzed correctly that a parked cpu hotplug thread of an offlined CPU
was still on the runqueue when the CPU came back online and tried to unpark
it. This causes the thread which invoked kthread_unpark() to call
wait_task_inactive() and subsequently schedule() with preemption disabled.
His proposed workaround was to "make sure" that a parked thread has
scheduled out when the CPU goes offline, so the situation cannot happen.

But that's still wrong because the root cause is not the fact that the
percpu thread is still on the runqueue and neither that preemption is
disabled, which could be simply solved by enabling preemption before
calling kthread_unpark().

The real issue is that the calling thread is the idle task of the upcoming
CPU, which is not supposed to call anything which might sleep.  The moron,
who wrote that code, missed completely that kthread_unpark() might end up
in schedule().

The solution is simpler than expected. The thread which controls the
hotplug operation is waiting for the CPU to call complete() on the hotplug
state completion. So the idle task of the upcoming CPU can set its state to
CPUHP_AP_ONLINE_IDLE and invoke complete(). This in turn wakes the control
task on a different CPU, which then can safely do the unpark and kick the
now unparked hotplug thread of the upcoming CPU to complete the bringup to
the final target state.

Control CPU                     AP

bringup_cpu();
  __cpu_up()  ------------>
				bringup_ap();
  bringup_wait_for_ap()
    wait_for_completion();
                                cpuhp_online_idle();
                <------------    complete();
    unpark(AP->stopper);
    unpark(AP->hotplugthread);
                                while(1)
                                  do_idle();
    kick(AP->hotplugthread);
    wait_for_completion();	hotplug_thread()
				  run_online_callbacks();
				  complete();

Fixes: 8df3e07e7f21 ("cpu/hotplug: Let upcoming cpu bring itself fully up")
Reported-by: Vikram Mulukutla 
Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra 
Cc: Sebastian Sewior 
Cc: Rusty Russell 
Cc: Tejun Heo 
Cc: Andrew Morton 
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1707042218020.2131@nanos
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

drm/i915: reintroduce VLV/CHV PFI programming power domain workaround

2017-07-27T22:10:24+00:00

commit 9c75b185274b7766fe69c2e73607c1ed780b284b upstream.

There are still cases on these platforms where an attempt is made to
configure the CDCLK while the power domain is off, like when coming back
from a suspend.  So the workaround below is still needed.

This effectively reverts commit 63ff30442519 ("drm/i915: Nuke the
VLV/CHV PFI programming power domain workaround").

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101517
Suggested-by: Ville Syrjälä 
Signed-off-by: Gabriel Krisman Bertazi 
Link: http://patchwork.freedesktop.org/patch/msgid/20170628210605.4994-1-krisman@collabora.co.uk
Reviewed-by: Ville Syrjälä 
Signed-off-by: Ville Syrjälä 
(cherry picked from commit 886015a0ad43c7fc034b23ea4614ba39162f9ddd)
Signed-off-by: Jani Nikula 
Signed-off-by: Greg Kroah-Hartman

drm/i915: Hold RPM wakelock while initializing OA buffer

2017-07-27T22:10:24+00:00

commit 04941829b0049d2446c7042ab9686dd057d809a6 upstream.

OA buffer initialization involves access to HW registers to set
the OA base, head and tail. Ensure device is awake while setting
these. With this, all oa.ops are covered under RPM and forcewake
wakelock.

Cc: Lionel Landwerlin 
Signed-off-by: Sagar Arun Kamble 
Reviewed-by: Lionel Landwerlin 
Signed-off-by: Maarten Lankhorst 
Link: http://patchwork.freedesktop.org/patch/msgid/1498585181-23048-1-git-send-email-sagar.a.kamble@intel.com
Fixes: d79651522e89c ("drm/i915: Enable i915 perf stream for Haswell OA unit")
(cherry picked from commit 987f8c444aa2c33d98e7030d0c5f0a5325cc84ea)
Signed-off-by: Jani Nikula 
Signed-off-by: Greg Kroah-Hartman

drm/i915/fbdev: Check for existence of ifbdev->vma before operations

2017-07-27T22:10:24+00:00

commit 7581d5ca2bb269cfc2ce2d0cb489aac513167f6b upstream.

Commit fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer
flushes") adds a dependency to ifbdev->vma when flushing the framebufer,
but the checks are only against the existence of the ifbdev->fb and not
against ifbdev->vma. This leaves a window of opportunity where we may
try to operate on the fbdev prior to it being probed (thanks to
asynchronous booting).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101534
Fixes: fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer flushes")
Signed-off-by: Chris Wilson 
Cc: Joonas Lahtinen 
Cc: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/20170622160211.783-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin 
(cherry picked from commit 15727ed0d944ce1dec8b9e1082dd3df29a0fdf44)
Signed-off-by: Jani Nikula 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix kmemleak in instance_rmdir

2017-07-27T22:10:24+00:00

commit db9108e054700c96322b0f0028546aa4e643cf0b upstream.

Hit the kmemleak when executing instance_rmdir, it forgot releasing
mem of tracing_cpumask. With this fix, the warn does not appear any
more.

unreferenced object 0xffff93a8dfaa7c18 (size 8):
  comm "mkdir", pid 1436, jiffies 4294763622 (age 9134.308s)
  hex dump (first 8 bytes):
    ff ff ff ff ff ff ff ff                          ........
  backtrace:
    [] kmemleak_alloc+0x4a/0xa0
    [] __kmalloc_node+0xf1/0x280
    [] alloc_cpumask_var_node+0x23/0x30
    [] alloc_cpumask_var+0xe/0x10
    [] instance_mkdir+0x90/0x240
    [] tracefs_syscall_mkdir+0x40/0x70
    [] vfs_mkdir+0x109/0x1b0
    [] SyS_mkdir+0xd0/0x100
    [] do_syscall_64+0x67/0x150
    [] return_from_SYSCALL_64+0x0/0x6a
    [] 0xffffffffffffffff

Link: http://lkml.kernel.org/r/1500546969-12594-1-git-send-email-chuhu@redhat.com

Fixes: ccfe9e42e451 ("tracing: Make tracing_cpumask available for all instances")
Signed-off-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

2017-07-27T22:10:24+00:00

commit 975e83cfb8dc16e7a2fdc58188c77c0c605876c2 upstream.

If the genpd->attach_dev or genpd->power_on fails, genpd_dev_pm_attach
may return -EPROBE_DEFER initially. However genpd_alloc_dev_data sets
the PM domain for the device unconditionally.

When subsequent attempts are made to call genpd_dev_pm_attach, it may
return -EEXISTS checking dev->pm_domain without re-attempting to call
attach_dev or power_on.

platform_drv_probe then attempts to call drv->probe as the return value
-EEXIST != -EPROBE_DEFER, which may end up in a situation where the
device is accessed without it's power domain switched on.

Fixes: f104e1e5ef57 (PM / Domains: Re-order initialization of generic_pm_domain_data)
Signed-off-by: Sudeep Holla 
Acked-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman