linux-stable.git/kernel, branch v3.18.9

ntp: Fixup adjtimex freq validation on 32-bit systems

2015-03-06T22:53:01+00:00

commit 29183a70b0b828500816bd794b3fe192fce89f73 upstream.

Additional validation of adjtimex freq values to avoid
potential multiplication overflows were added in commit
5e5aeb4367b (time: adjtimex: Validate the ADJ_FREQUENCY values)

Unfortunately the patch used LONG_MAX/MIN instead of
LLONG_MAX/MIN, which was fine on 64-bit systems, but being
much smaller on 32-bit systems caused false positives
resulting in most direct frequency adjustments to fail w/
EINVAL.

ntpd only does direct frequency adjustments at startup, so
the issue was not as easily observed there, but other time
sync applications like ptpd and chrony were more effected by
the bug.

See bugs:

  https://bugzilla.kernel.org/show_bug.cgi?id=92481
  https://bugzilla.redhat.com/show_bug.cgi?id=1188074

This patch changes the checks to use LLONG_MAX for
clarity, and additionally the checks are disabled
on 32-bit systems since LLONG_MAX/PPM_SCALE is always
larger then the 32-bit long freq value, so multiplication
overflows aren't possible there.

Reported-by: Josh Boyer 
Reported-by: George Joseph 
Tested-by: George Joseph 
Signed-off-by: John Stultz 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Sasha Levin 
Link: http://lkml.kernel.org/r/1423553436-29747-1-git-send-email-john.stultz@linaro.org
[ Prettified the changelog and the comments a bit. ]
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

kdb: fix incorrect counts in KDB summary command output

2015-03-06T22:53:01+00:00

commit 146755923262037fc4c54abc28c04b1103f3cc51 upstream.

The output of KDB 'summary' command should report MemTotal, MemFree
and Buffers output in kB. Current codes report in unit of pages.

A define of K(x) as
is defined in the code, but not used.

This patch would apply the define to convert the values to kB.
Please include me on Cc on replies. I do not subscribe to linux-kernel.

Signed-off-by: Jay Lan 
Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

ring-buffer: Do not wake up a splice waiter when page is not full

2015-03-06T22:52:59+00:00

commit 1e0d6714aceb770b04161fbedd7765d0e1fc27bd upstream.

When an application connects to the ring buffer via splice, it can only
read full pages. Splice does not work with partial pages. If there is
not enough data to fill a page, the splice command will either block
or return -EAGAIN (if set to nonblock).

Code was added where if the page is not full, to just sleep again.
The problem is, it will get woken up again on the next event. That
is, when something is written into the ring buffer, if there is a waiter
it will wake it up. The waiter would then check the buffer, see that
it still does not have enough data to fill a page and go back to sleep.
To make matters worse, when the waiter goes back to sleep, it could
cause another event, which would wake it back up again to see it
doesn't have enough data and sleep again. This produces a tremendous
overhead and fills the ring buffer with noise.

For example, recording sched_switch on an idle system for 10 seconds
produces 25,350,475 events!!!

Create another wait queue for those waiters wanting full pages.
When an event is written, it only wakes up waiters if there's a full
page of data. It does not wake up the waiter if the page is not yet
full.

After this change, recording sched_switch on an idle system for 10
seconds produces only 800 events. Getting rid of 25,349,675 useless
events (99.9969% of events!!), is something to take seriously.

Cc: Rabin Vincent 
Fixes: e30f53aad220 "tracing: Do not busy wait in buffer splice"
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix unmapping loop in tracing_mark_write

2015-03-06T22:52:55+00:00

commit 7215853e985a4bef1a6c14e00e89dfec84f1e457 upstream.

Commit 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce introduced
an array map_pages that contains the addresses returned by
kmap_atomic. However, when unmapping those pages, map_pages[0]
is unmapped before map_pages[1], breaking the nesting requirement
as specified in the documentation for kmap_atomic/kunmap_atomic.

This was caught by the highmem debug code present in kunmap_atomic.
Fix the loop to do the unmapping properly.

Link: http://lkml.kernel.org/r/1418871056-6614-1-git-send-email-markivx@codeaurora.org

Reviewed-by: Stephen Boyd 
Reported-by: Lime Yang 
Signed-off-by: Vikram Mulukutla 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

hrtimer: Fix incorrect tai offset calculation for non high-res timer systems

2015-02-11T07:00:56+00:00

commit 2d926c15d629a13914ce3e5f26354f6a0ac99e70 upstream.

I noticed some CLOCK_TAI timer test failures on one of my
less-frequently used configurations. And after digging in I
found in 76f4108892d9 (Cleanup hrtimer accessors to the
timekepeing state), the hrtimer_get_softirq_time tai offset
calucation was incorrectly rewritten, as the tai offset we
return shold be from CLOCK_MONOTONIC, and not CLOCK_REALTIME.

This results in CLOCK_TAI timers expiring early on non-highres
capable machines.

This patch fixes the issue, calculating the tai time properly
from the monotonic base.

Signed-off-by: John Stultz 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1423097126-10236-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

smpboot: Add missing get_online_cpus() in smpboot_register_percpu_thread()

2015-02-11T07:00:56+00:00

commit 4bee96860a65c3a62d332edac331b3cf936ba3ad upstream.

The following race exists in the smpboot percpu threads management:

CPU0	      	   	     CPU1
cpu_up(2)
  get_online_cpus();
  smpboot_create_threads(2);
			     smpboot_register_percpu_thread();
			     for_each_online_cpu();
			       __smpboot_create_thread();
  __cpu_up(2);

This results in a missing per cpu thread for the newly onlined cpu2 and
in a NULL pointer dereference on a consecutive offline of that cpu.

Proctect smpboot_register_percpu_thread() with get_online_cpus() to
prevent that.

[ tglx: Massaged changelog and removed the change in
        smpboot_unregister_percpu_thread() because that's an
        optimization and therefor not stable material. ]

Signed-off-by: Lai Jiangshan 
Cc: Thomas Gleixner 
Cc: Rusty Russell 
Cc: Peter Zijlstra 
Cc: Srivatsa S. Bhat 
Cc: David Rientjes 
Link: http://lkml.kernel.org/r/1406777421-12830-1-git-send-email-laijs@cn.fujitsu.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

time: adjtimex: Validate the ADJ_FREQUENCY values

2015-01-30T01:40:44+00:00

commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream.

Verify that the frequency value from userspace is valid and makes sense.

Unverified values can cause overflows later on.

Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Signed-off-by: Sasha Levin 
[jstultz: Fix up bug for negative values and drop redunent cap check]
Signed-off-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman

time: settimeofday: Validate the values of tv from user

2015-01-30T01:40:44+00:00

commit 6ada1fc0e1c4775de0e043e1bd3ae9d065491aa5 upstream.

An unvalidated user input is multiplied by a constant, which can result in
an undefined behaviour for large values. While this is validated later,
we should avoid triggering undefined behaviour.

Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Signed-off-by: Sasha Levin 
[jstultz: include trivial milisecond->microsecond correction noticed
by Andy]
Signed-off-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman

workqueue: fix subtle pool management issue which can stall whole worker_pool

2015-01-30T01:40:43+00:00

commit 29187a9eeaf362d8422e62e17a22a6e115277a49 upstream.

A worker_pool's forward progress is guaranteed by the fact that the
last idle worker assumes the manager role to create more workers and
summon the rescuers if creating workers doesn't succeed in timely
manner before proceeding to execute work items.

This manager role is implemented in manage_workers(), which indicates
whether the worker may proceed to work item execution with its return
value.  This is necessary because multiple workers may contend for the
manager role, and, if there already is a manager, others should
proceed to work item execution.

Unfortunately, the function also indicates that the worker may proceed
to work item execution if need_to_create_worker() is false at the head
of the function.  need_to_create_worker() tests the following
conditions.

	pending work items && !nr_running && !nr_idle

The first and third conditions are protected by pool->lock and thus
won't change while holding pool->lock; however, nr_running can change
asynchronously as other workers block and resume and while it's likely
to be zero, as someone woke this worker up in the first place, some
other workers could have become runnable inbetween making it non-zero.

If this happens, manage_worker() could return false even with zero
nr_idle making the worker, the last idle one, proceed to execute work
items.  If then all workers of the pool end up blocking on a resource
which can only be released by a work item which is pending on that
pool, the whole pool can deadlock as there's no one to create more
workers or summon the rescuers.

This patch fixes the problem by removing the early exit condition from
maybe_create_worker() and making manage_workers() return false iff
there's already another manager, which ensures that the last worker
doesn't start executing work items.

We can leave the early exit condition alone and just ignore the return
value but the only reason it was put there is because the
manage_workers() used to perform both creations and destructions of
workers and thus the function may be invoked while the pool is trying
to reduce the number of workers.  Now that manage_workers() is called
only when more workers are needed, the only case this early exit
condition is triggered is rare race conditions rendering it pointless.

Tested with simulated workload and modified workqueue code which
trigger the pool deadlock reliably without this patch.

Signed-off-by: Tejun Heo 
Reported-by: Eric Sandeen 
Link: http://lkml.kernel.org/g/54B019F4.8030009@sandeen.net
Cc: Dave Chinner 
Cc: Lai Jiangshan 
Signed-off-by: Greg Kroah-Hartman

ftrace: Check both notrace and filter for old hash

2015-01-27T16:29:41+00:00

commit 7485058eea40783ac142a60c3e799fc66ce72583 upstream.

Using just the filter for checking for trampolines or regs is not enough
when updating the code against the records that represent all functions.
Both the filter hash and the notrace hash need to be checked.

To trigger this bug (using trace-cmd and perf):

 # perf probe -a do_fork
 # trace-cmd start -B foo -e probe
 # trace-cmd record -p function_graph -n do_fork sleep 1

The trace-cmd record at the end clears the filter before it disables
function_graph tracing and then that causes the accounting of the
ftrace function records to become incorrect and causes ftrace to bug.

Link: http://lkml.kernel.org/r/20150114154329.358378039@goodmis.org

[ still need to switch old_hash_ops to old_ops_hash ]
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman