linux-stable.git/kernel, branch v4.9.33

kernel/watchdog: prevent false hardlockup on overloaded system

2017-06-17T04:41:57+00:00

[ Upstream commit b94f51183b0617e7b9b4fb4137d4cf1cab7547c2 ]

On an overloaded system, it is possible that a change in the watchdog
threshold can be delayed long enough to trigger a false positive.

This can easily be achieved by having a cpu spinning indefinitely on a
task, while another cpu updates watchdog threshold.

What happens is while trying to park the watchdog threads, the hrtimers
on the other cpus trigger and reprogram themselves with the new slower
watchdog threshold.  Meanwhile, the nmi watchdog is still programmed
with the old faster threshold.

Because the one cpu is blocked, it prevents the thread parking on the
other cpus from completing, which is needed to shutdown the nmi watchdog
and reprogram it correctly.  As a result, a false positive from the nmi
watchdog is reported.

Fix this by setting a park_in_progress flag to block all lockups until
the parking is complete.

Fix provided by Ulrich Obergfell.

[akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/]
Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.com
Signed-off-by: Don Zickus 
Reviewed-by: Aaron Tomlin 
Cc: Ulrich Obergfell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 

Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

kernel/watchdog.c: move shared definitions to nmi.h

2017-06-17T04:41:57+00:00

[ Upstream commit 249e52e35580fcfe5dad53a7dcd7c1252788749c ]

Patch series "Clean up watchdog handlers", v2.

This is an attempt to cleanup watchdog handlers.  Right now,
kernel/watchdog.c implements both softlockup and hardlockup detectors.
Softlockup code is generic.  Hardlockup code is arch specific.  Some
architectures don't use hardlockup detectors.  They use their own
watchdog detectors.  To make both these combination work, we have
numerous #ifdefs in kernel/watchdog.c.

We are trying here to make these handlers independent of each other.
Also provide an interface for architectures to implement their own
handlers.  watchdog_nmi_enable and watchdog_nmi_disable will be defined
as weak such that architectures can override its definitions.

Thanks to Don Zickus for his suggestions.
Here are our previous discussions
http://www.spinics.net/lists/sparclinux/msg16543.html
http://www.spinics.net/lists/sparclinux/msg16441.html

This patch (of 3):

Move shared macros and definitions to nmi.h so that watchdog.c, new file
watchdog_hld.c or any other architecture specific handler can use those
definitions.

Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.com
Signed-off-by: Babu Moger 
Acked-by: Don Zickus 
Cc: Ingo Molnar 
Cc: Jiri Kosina 
Cc: Andi Kleen 
Cc: Yaowei Bai 
Cc: Aaron Tomlin 
Cc: Ulrich Obergfell 
Cc: Tejun Heo 
Cc: Hidehiro Kawai 
Cc: Josh Hunt 
Cc: "David S. Miller" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

kernel/watchdog.c: move hardlockup detector to separate file

2017-06-17T04:41:57+00:00

[ Upstream commit 73ce0511c43686095efd2f65ef564aab952e07bc ]

Separate hardlockup code from watchdog.c and move it to watchdog_hld.c.
It is mostly straight forward.  Remove everything inside
CONFIG_HARDLOCKUP_DETECTORS.  This code will go to file watchdog_hld.c.
Also update the makefile accordigly.

Link: http://lkml.kernel.org/r/1478034826-43888-3-git-send-email-babu.moger@oracle.com
Signed-off-by: Babu Moger 
Acked-by: Don Zickus 
Cc: Ingo Molnar 
Cc: Jiri Kosina 
Cc: Andi Kleen 
Cc: Yaowei Bai 
Cc: Aaron Tomlin 
Cc: Ulrich Obergfell 
Cc: Tejun Heo 
Cc: Hidehiro Kawai 
Cc: Josh Hunt 
Cc: "David S. Miller" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

kernel/ucount.c: mark user_header with kmemleak_ignore()

2017-06-17T04:41:51+00:00

[ Upstream commit ed5bd7dc88edf4a4a9c67130742b1b59aa017a5f ]

The user_header gets caught by kmemleak with the following splat as
missing a free:

  unreferenced object 0xffff99667a733d80 (size 96):
  comm "swapper/0", pid 1, jiffies 4294892317 (age 62191.468s)
  hex dump (first 32 bytes):
    a0 b6 92 b4 ff ff ff ff 00 00 00 00 01 00 00 00  ................
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
     kmemleak_alloc+0x4a/0xa0
     __kmalloc+0x144/0x260
     __register_sysctl_table+0x54/0x5e0
     register_sysctl+0x1b/0x20
     user_namespace_sysctl_init+0x17/0x34
     do_one_initcall+0x52/0x1a0
     kernel_init_freeable+0x173/0x200
     kernel_init+0xe/0x100
     ret_from_fork+0x2c/0x40

The BUG_ON()s are intended to crash so no need to clean up after
ourselves on error there.  This is also a kernel/ subsys_init() we don't
need a respective exit call here as this is never modular, so just white
list it.

Link: http://lkml.kernel.org/r/20170203211404.31458-1-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez 
Cc: Eric W. Biederman 
Cc: Kees Cook 
Cc: Nikolay Borisov 
Cc: Serge Hallyn 
Cc: Jan Kara 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start()

2017-06-14T13:06:05+00:00

commit 4296f23ed49a15d36949458adcc66ff993dee2a8 upstream.

sugov_start() only initializes struct sugov_cpu per-CPU structures
for shared policies, but it should do that for single-CPU policies too.

That in particular makes the IO-wait boost mechanism work in the
cases when cpufreq policies correspond to individual CPUs.

Fixes: 21ca6d2c52f8 (cpufreq: schedutil: Add iowait boosting)
Signed-off-by: Rafael J. Wysocki 
Acked-by: Viresh Kumar 
Signed-off-by: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

cpufreq: schedutil: move cached_raw_freq to struct sugov_policy

2017-06-14T13:06:05+00:00

commit 6c4f0fa643cb9e775dcc976e3db00d649468ff1d upstream.

cached_raw_freq applies to the entire cpufreq policy and not individual
CPUs. Apart from wasting per-cpu memory, it is actually wrong to keep it
in struct sugov_cpu as we may end up comparing next_freq with a stale
cached_raw_freq of a random CPU.

Move cached_raw_freq to struct sugov_policy.

Fixes: 5cbea46984d6 (cpufreq: schedutil: map raw required frequency to driver frequency)
Signed-off-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Drop the device lock on error

2017-06-14T13:06:04+00:00

commit 40da1b11f01e43aad1aa6cea64681b6125e8a2a7 upstream.

If a custom CPU target is specified and that one is not available _or_
can't be interrupted then the code returns to userland without dropping a
lock as notices by lockdep:

|echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target
| ================================================
| [ BUG: lock held when returning to user space! ]
| ------------------------------------------------
| bash/503 is leaving the kernel with locks still held!
| 1 lock held by bash/503:
|  #0:  (device_hotplug_lock){+.+...}, at: [] lock_device_hotplug_sysfs+0x10/0x40

So release the lock then.

Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable")
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20170602142714.3ogo25f2wbq6fjpj@linutronix.de
Signed-off-by: Greg Kroah-Hartman

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

2017-06-14T13:06:03+00:00

commit cc1582c231ea041fbc68861dfaf957eaf902b829 upstream.

When doing sampling, for example:

  perf record -e cycles:u ...

On workloads that do a lot of kernel entry/exits we see kernel
samples, even though :u is specified. This is due to skid existing.

This might be a security issue because it can leak kernel addresses even
though kernel sampling support is disabled.

The patch drops the kernel samples if exclude_kernel is specified.

For example, test on Haswell desktop:

  perf record -e cycles:u 
  perf report --stdio

Before patch applied:

    99.77%  mgen     mgen              [.] buf_read
     0.20%  mgen     mgen              [.] rand_buf_init
     0.01%  mgen     [kernel.vmlinux]  [k] apic_timer_interrupt
     0.00%  mgen     mgen              [.] last_free_elem
     0.00%  mgen     libc-2.23.so      [.] __random_r
     0.00%  mgen     libc-2.23.so      [.] _int_malloc
     0.00%  mgen     mgen              [.] rand_array_init
     0.00%  mgen     [kernel.vmlinux]  [k] page_fault
     0.00%  mgen     libc-2.23.so      [.] __random
     0.00%  mgen     libc-2.23.so      [.] __strcasestr
     0.00%  mgen     ld-2.23.so        [.] strcmp
     0.00%  mgen     ld-2.23.so        [.] _dl_start
     0.00%  mgen     libc-2.23.so      [.] sched_setaffinity@@GLIBC_2.3.4
     0.00%  mgen     ld-2.23.so        [.] _start

We can see kernel symbols apic_timer_interrupt and page_fault.

After patch applied:

    99.79%  mgen     mgen           [.] buf_read
     0.19%  mgen     mgen           [.] rand_buf_init
     0.00%  mgen     libc-2.23.so   [.] __random_r
     0.00%  mgen     mgen           [.] rand_array_init
     0.00%  mgen     mgen           [.] last_free_elem
     0.00%  mgen     libc-2.23.so   [.] vfprintf
     0.00%  mgen     libc-2.23.so   [.] rand
     0.00%  mgen     libc-2.23.so   [.] __random
     0.00%  mgen     libc-2.23.so   [.] _int_malloc
     0.00%  mgen     libc-2.23.so   [.] _IO_doallocbuf
     0.00%  mgen     ld-2.23.so     [.] do_lookup_x
     0.00%  mgen     ld-2.23.so     [.] open_verify.constprop.7
     0.00%  mgen     ld-2.23.so     [.] _dl_important_hwcaps
     0.00%  mgen     libc-2.23.so   [.] sched_setaffinity@@GLIBC_2.3.4
     0.00%  mgen     ld-2.23.so     [.] _start

There are only userspace symbols.

Signed-off-by: Jin Yao 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: acme@kernel.org
Cc: jolsa@kernel.org
Cc: kan.liang@intel.com
Cc: mark.rutland@arm.com
Cc: will.deacon@arm.com
Cc: yao.jin@intel.com
Link: http://lkml.kernel.org/r/1495706947-3744-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

cpuset: consider dying css as offline

2017-06-14T13:06:00+00:00

commit 41c25707d21716826e3c1f60967f5550610ec1c9 upstream.

In most cases, a cgroup controller don't care about the liftimes of
cgroups.  For the controller, a css becomes online when ->css_online()
is called on it and offline when ->css_offline() is called.

However, cpuset is special in that the user interface it exposes cares
whether certain cgroups exist or not.  Combined with the RCU delay
between cgroup removal and css offlining, this can lead to user
visible behavior oddities where operations which should succeed after
cgroup removals fail for some time period.  The effects of cgroup
removals are delayed when seen from userland.

This patch adds css_is_dying() which tests whether offline is pending
and updates is_cpuset_online() so that the function returns false also
while offline is pending.  This gets rid of the userland visible
delays.

Signed-off-by: Tejun Heo 
Reported-by: Daniel Jordan 
Link: http://lkml.kernel.org/r/327ca1f5-7957-fbb9-9e5f-9ba149d40ba2@oracle.com
Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

cgroup: Prevent kill_css() from being called more than once

2017-06-14T13:06:00+00:00

commit 33c35aa4817864e056fd772230b0c6b552e36ea2 upstream.

The kill_css() function may be called more than once under the condition
that the css was killed but not physically removed yet followed by the
removal of the cgroup that is hosting the css. This patch prevents any
harmm from being done when that happens.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman