linux-stable.git/kernel, branch v4.4.80

sched/cputime: Fix prev steal time accouting during CPU hotplug

2017-08-07T02:19:43+00:00

commit 3d89e5478bf550a50c99e93adf659369798263b0 upstream.

Commit:

  e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")

... set rq->prev_* to 0 after a CPU hotplug comes back, in order to
fix the case where (after CPU hotplug) steal time is smaller than
rq->prev_steal_time.

However, this should never happen. Steal time was only smaller because of the
KVM-specific bug fixed by the previous patch.  Worse, the previous patch
triggers a bug on CPU hot-unplug/plug operation: because
rq->prev_steal_time is cleared, all of the CPU's past steal time will be
accounted again on hot-plug.

Since the root cause has been fixed, we can just revert commit e9532e69b8d1.

Signed-off-by: Wanpeng Li 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Paolo Bonzini 
Cc: Frederic Weisbecker 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Radim Krčmář 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Fixes: 'commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")'
Link: http://lkml.kernel.org/r/1465813966-3116-3-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Andres Oportus 
Acked-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

/proc/iomem: only expose physical resource addresses to privileged users

2017-08-07T02:19:42+00:00

commit 51d7b120418e99d6b3bf8df9eb3cc31e8171dee4 upstream.

In commit c4004b02f8e5b ("x86: remove the kernel code/data/bss resources
from /proc/iomem") I was hoping to remove the phyiscal kernel address
data from /proc/iomem entirely, but that had to be reverted because some
system programs actually use it.

This limits all the detailed resource information to properly
credentialed users instead.

[sumits: this is used in Ubuntu as a fix for CVE-2015-8944]

Signed-off-by: Linus Torvalds 
Signed-off-by: Sumit Semwal 
Signed-off-by: Greg Kroah-Hartman

sched/cgroup: Move sched_online_group() back into css_online() to fix crash

2017-08-07T02:19:42+00:00

commit 96b777452d8881480fd5be50112f791c17db4b6b upstream.

Commit:

  2f5177f0fd7e ("sched/cgroup: Fix/cleanup cgroup teardown/init")

.. moved sched_online_group() from css_online() to css_alloc().
It exposes half-baked task group into global lists before initializing
generic cgroup stuff.

LTP testcase (third in cgroup_regression_test) written for testing
similar race in kernels 2.6.26-2.6.28 easily triggers this oops:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: kernfs_path_from_node_locked+0x260/0x320
  CPU: 1 PID: 30346 Comm: cat Not tainted 4.10.0-rc5-test #4
  Call Trace:
  ? kernfs_path_from_node+0x4f/0x60
  kernfs_path_from_node+0x3e/0x60
  print_rt_rq+0x44/0x2b0
  print_rt_stats+0x7a/0xd0
  print_cpu+0x2fc/0xe80
  ? __might_sleep+0x4a/0x80
  sched_debug_show+0x17/0x30
  seq_read+0xf2/0x3b0
  proc_reg_read+0x42/0x70
  __vfs_read+0x28/0x130
  ? security_file_permission+0x9b/0xc0
  ? rw_verify_area+0x4e/0xb0
  vfs_read+0xa5/0x170
  SyS_read+0x46/0xa0
  entry_SYSCALL_64_fastpath+0x1e/0xad

Here the task group is already linked into the global RCU-protected 'task_groups'
list, but the css->cgroup pointer is still NULL.

This patch reverts this chunk and moves online back to css_online().

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Fixes: 2f5177f0fd7e ("sched/cgroup: Fix/cleanup cgroup teardown/init")
Link: http://lkml.kernel.org/r/148655324740.424917.5302984537258726349.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Matt Fleming 
Signed-off-by: Greg Kroah-Hartman

alarmtimer: don't rate limit one-shot timers

2017-07-27T22:06:10+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.

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

tracing: Fix kmemleak in instance_rmdir

2017-07-27T22:06:10+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

Revert "perf/core: Drop kernel samples even though :u is specified"

2017-07-27T22:06:09+00:00

commit 6a8a75f3235724c5941a33e287b2f98966ad14c5 upstream.

This reverts commit cc1582c231ea041fbc68861dfaf957eaf902b829.

This commit introduced a regression that broke rr-project, which uses sampling
events to receive a signal on overflow (but does not care about the contents
of the sample). These signals are critical to the correct operation of rr.

There's been some back and forth about how to fix it - but to not keep
applications in limbo queue up a revert.

Reported-by: Kyle Huey 
Acked-by: Kyle Huey 
Acked-by: Peter Zijlstra 
Cc: Jin Yao 
Cc: Vince Weaver 
Cc: Linus Torvalds 
Cc: Will Deacon 
Cc: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Stephane Eranian 
Cc: Namhyung Kim 
Cc: Jiri Olsa 
Link: http://lkml.kernel.org/r/20170628105600.GC5981@leverpostej
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix uninitialized variable in match_records()

2017-07-27T22:06:07+00:00

commit 2e028c4fe12907f226b8221815f16c2486ad3aa7 upstream.

My static checker complains that if "func" is NULL then "clear_filter"
is uninitialized.  This seems like it could be true, although it's
possible something subtle is happening that I haven't seen.

    kernel/trace/ftrace.c:3844 match_records()
    error: uninitialized symbol 'clear_filter'.

Link: http://lkml.kernel.org/r/20170712073556.h6tkpjcdzjaozozs@mwanda

Fixes: f0a3b154bd7 ("ftrace: Clarify code for mod command")
Signed-off-by: Dan Carpenter 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results

2017-07-21T05:44:59+00:00

commit c59f29cb144a6a0dfac16ede9dc8eafc02dc56ca upstream.

The 's' flag is supposed to indicate that a softirq is running. This
can be detected by testing the preempt_count with SOFTIRQ_OFFSET.

The current code tests the preempt_count with SOFTIRQ_MASK, which
would be true even when softirqs are disabled but not serving a
softirq.

Link: http://lkml.kernel.org/r/1481300417-3564-1-git-send-email-pkondeti@codeaurora.org

Signed-off-by: Pavankumar Kondeti 
Signed-off-by: Steven Rostedt 
Signed-off-by: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

sched/topology: Optimize build_group_mask()

2017-07-21T05:44:59+00:00

commit f32d782e31bf079f600dcec126ed117b0577e85c upstream.

The group mask is always used in intersection with the group CPUs. So,
when building the group mask, we don't have to care about CPUs that are
not part of the group.

Signed-off-by: Lauro Ramos Venancio 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: lwang@redhat.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1492717903-5195-2-git-send-email-lvenanci@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched/topology: Fix overlapping sched_group_mask

2017-07-21T05:44:59+00:00

commit 73bb059f9b8a00c5e1bf2f7ca83138c05d05e600 upstream.

The point of sched_group_mask is to select those CPUs from
sched_group_cpus that can actually arrive at this balance domain.

The current code gets it wrong, as can be readily demonstrated with a
topology like:

  node   0   1   2   3
    0:  10  20  30  20
    1:  20  10  20  30
    2:  30  20  10  20
    3:  20  30  20  10

Where (for example) domain 1 on CPU1 ends up with a mask that includes
CPU0:

  [] CPU1 attaching sched-domain:
  []  domain 0: span 0-2 level NUMA
  []   groups: 1 (mask: 1), 2, 0
  []   domain 1: span 0-3 level NUMA
  []    groups: 0-2 (mask: 0-2) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072)

This causes sched_balance_cpu() to compute the wrong CPU and
consequently should_we_balance() will terminate early resulting in
missed load-balance opportunities.

The fixed topology looks like:

  [] CPU1 attaching sched-domain:
  []  domain 0: span 0-2 level NUMA
  []   groups: 1 (mask: 1), 2, 0
  []   domain 1: span 0-3 level NUMA
  []    groups: 0-2 (mask: 1) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072)

(note: this relies on OVERLAP domains to always have children, this is
 true because the regular topology domains are still here -- this is
 before degenerate trimming)

Debugged-by: Lauro Ramos Venancio 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Fixes: e3589f6c81e4 ("sched: Allow for overlapping sched_domain spans")
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman