linux-stable.git/kernel, branch v4.1.41

sched/fair: Initialize throttle_count for new task-groups lazily

2017-06-13T13:29:21+00:00

[ Upstream commit 094f469172e00d6ab0a3130b0e01c83b3cf3a98d ]

Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().

This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: bsegall@google.com
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

sched/fair: Do not announce throttled next buddy in dequeue_task_fair()

2017-06-13T13:29:21+00:00

[ Upstream commit 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 ]

Hierarchy could be already throttled at this point. Throttled next
buddy could trigger a NULL pointer dereference in pick_next_task_fair().

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Ben Segall 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

tracing/kprobes: Enforce kprobes teardown after testing

2017-06-08T10:12:46+00:00

[ Upstream commit 30e7d894c1478c88d50ce94ddcdbd7f9763d9cdd ]

Enabling the tracer selftest triggers occasionally the warning in
text_poke(), which warns when the to be modified page is not marked
reserved.

The reason is that the tracer selftest installs kprobes on functions marked
__init for testing. These probes are removed after the tests, but that
removal schedules the delayed kprobes_optimizer work, which will do the
actual text poke. If the work is executed after the init text is freed,
then the warning triggers. The bug can be reproduced reliably when the work
delay is increased.

Flush the optimizer work and wait for the optimizing/unoptimizing lists to
become empty before returning from the kprobes tracer selftest. That
ensures that all operations which were queued due to the probes removal
have completed.

Link: http://lkml.kernel.org/r/20170516094802.76a468bb@gandalf.local.home

Signed-off-by: Thomas Gleixner 
Acked-by: Masami Hiramatsu 
Cc: stable@vger.kernel.org
Fixes: 6274de498 ("kprobes: Support delayed unoptimizing")
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

genirq: Introduce struct irq_common_data to host shared irq data

2017-06-08T10:12:19+00:00

[ Upstream commit 0d0b4c866bcce647f40d73efe5e90aeeb079050a ]

With the introduction of hierarchy irqdomain, struct irq_data becomes
per-chip instead of per-irq and there may be multiple irq_datas
associated with the same irq. Some per-irq data stored in struct
irq_data now may get duplicated into multiple irq_datas, and causes
inconsistent view.

So introduce struct irq_common_data to host per-irq common data and to
achieve consistent view among irq_chips.

Signed-off-by: Jiang Liu 
Cc: Konrad Rzeszutek Wilk 
Cc: Tony Luck 
Cc: Bjorn Helgaas 
Cc: Benjamin Herrenschmidt 
Cc: Randy Dunlap 
Cc: Yinghai Lu 
Cc: Borislav Petkov 
Cc: Jason Cooper 
Cc: Kevin Cernekee 
Cc: Arnd Bergmann 
Cc: Marc Zyngier 
Link: http://lkml.kernel.org/r/1433145945-789-4-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Sasha Levin

cgroup: use bitmask to filter for_each_subsys

2017-06-08T02:52:11+00:00

[ Upstream commit cb4a316752709be4a644f070440a8be470d92b7d ]

Add a new macro for_each_subsys_which that allows all enabled cgroup
subsystems to be filtered by a bitmask, such that mask & (1 << ssid)
determines if the subsystem is to be processed in the loop body (where
ssid is the unique id of the subsystem).

Also replace the need_forkexit_callback with two separate bitmasks for
each callback to make (ss->{fork,exit}) checks unnecessary.

tj: add a short comment for "if (!CGROUP_SUBSYS_COUNT)".

Signed-off-by: Aleksa Sarai 
Signed-off-by: Sasha Levin

sched, cgroup: reorganize threadgroup locking

2017-06-08T02:52:05+00:00

[ Upstream commit 7d7efec368d537226142cbe559f45797f18672f9 ]

threadgroup_change_begin/end() are used to mark the beginning and end
of threadgroup modifying operations to allow code paths which require
a threadgroup to stay stable across blocking operations to synchronize
against those sections using threadgroup_lock/unlock().

It's currently implemented as a general mechanism in sched.h using
per-signal_struct rwsem; however, this never grew non-cgroup use cases
and becomes noop if !CONFIG_CGROUPS.  It turns out that cgroups is
gonna be better served with a different sycnrhonization scheme and is
a bit silly to keep cgroups specific details as a general mechanism.

What's general here is identifying the places where threadgroups are
modified.  This patch restructures threadgroup locking so that
threadgroup_change_begin/end() become a place where subsystems which
need to sycnhronize against threadgroup changes can hook into.

cgroup_threadgroup_change_begin/end() which operate on the
per-signal_struct rwsem are created and threadgroup_lock/unlock() are
moved to cgroup.c and made static.

This is pure reorganization which doesn't cause any functional
changes.

Signed-off-by: Tejun Heo 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Sasha Levin

pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes

2017-06-08T02:50:41+00:00

[ Upstream commit b9a985db98961ae1ba0be169f19df1c567e4ffe0 ]

The code can potentially sleep for an indefinite amount of time in
zap_pid_ns_processes triggering the hung task timeout, and increasing
the system average.  This is undesirable.  Sleep with a task state of
TASK_INTERRUPTIBLE instead of TASK_UNINTERRUPTIBLE to remove these
undesirable side effects.

Apparently under heavy load this has been allowing Chrome to trigger
the hung time task timeout error and cause ChromeOS to reboot.

Reported-by: Vovo Yang 
Reported-by: Guenter Roeck 
Tested-by: Guenter Roeck 
Fixes: 6347e9009104 ("pidns: guarantee that the pidns init will be the last pidns process reaped")
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Sasha Levin

ring-buffer: Have ring_buffer_iter_empty() return true when empty

2017-05-17T19:08:23+00:00

[ Upstream commit 78f7a45dac2a2d2002f98a3a95f7979867868d73 ]

I noticed that reading the snapshot file when it is empty no longer gives a
status. It suppose to show the status of the snapshot buffer as well as how
to allocate and use it. For example:

 ># cat snapshot
 # tracer: nop
 #
 #
 # * Snapshot is allocated *
 #
 # Snapshot commands:
 # echo 0 > snapshot : Clears and frees snapshot buffer
 # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.
 #                      Takes a snapshot of the main buffer.
 # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free)
 #                      (Doesn't have to be '2' works with any number that
 #                       is not a '0' or '1')

But instead it just showed an empty buffer:

 ># cat snapshot
 # tracer: nop
 #
 # entries-in-buffer/entries-written: 0/0   #P:4
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |

What happened was that it was using the ring_buffer_iter_empty() function to
see if it was empty, and if it was, it showed the status. But that function
was returning false when it was empty. The reason was that the iter header
page was on the reader page, and the reader page was empty, but so was the
buffer itself. The check only tested to see if the iter was on the commit
page, but the commit page was no longer pointing to the reader page, but as
all pages were empty, the buffer is also.

Cc: stable@vger.kernel.org
Fixes: 651e22f2701b ("ring-buffer: Always reset iterator to reader page")
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

tracing: Allocate the snapshot buffer before enabling probe

2017-05-17T19:08:23+00:00

[ Upstream commit df62db5be2e5f070ecd1a5ece5945b590ee112e0 ]

Currently the snapshot trigger enables the probe and then allocates the
snapshot. If the probe triggers before the allocation, it could cause the
snapshot to fail and turn tracing off. It's best to allocate the snapshot
buffer first, and then enable the trigger. If something goes wrong in the
enabling of the trigger, the snapshot buffer is still allocated, but it can
also be freed by the user by writting zero into the snapshot buffer file.

Also add a check of the return status of alloc_snapshot().

Cc: stable@vger.kernel.org
Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes")
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

padata: free correct variable

2017-05-17T19:08:22+00:00

[ Upstream commit 07a77929ba672d93642a56dc2255dd21e6e2290b ]

The author meant to free the variable that was just allocated, instead
of the one that failed to be allocated, but made a simple typo. This
patch rectifies that.

Signed-off-by: Jason A. Donenfeld 
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu 
Signed-off-by: Sasha Levin