Commit graph

17365 commits

Author SHA1 Message Date
Eric Paris
aa4af831bb AUDIT: Allow login in non-init namespaces
It its possible to configure your PAM stack to refuse login if audit
messages (about the login) were unable to be sent.  This is common in
many distros and thus normal configuration of many containers.  The PAM
modules determine if audit is enabled/disabled in the kernel based on
the return value from sending an audit message on the netlink socket.
If userspace gets back ECONNREFUSED it believes audit is disabled in the
kernel.  If it gets any other error else it refuses to let the login
proceed.

Just about ever since the introduction of namespaces the kernel audit
subsystem has returned EPERM if the task sending a message was not in
the init user or pid namespace.  So many forms of containers have never
worked if audit was enabled in the kernel.

BUT if the container was not in net_init then the kernel network code
would send ECONNREFUSED (instead of the audit code sending EPERM).  Thus
by pure accident/dumb luck/bug if an admin configured the PAM stack to
reject all logins that didn't talk to audit, but then ran the login
untility in the non-init_net namespace, it would work!! Clearly this was
a bug, but it is a bug some people expected.

With the introduction of network namespace support in 3.14-rc1 the two
bugs stopped cancelling each other out.  Now, containers in the
non-init_net namespace refused to let users log in (just like PAM was
configfured!) Obviously some people were not happy that what used to let
users log in, now didn't!

This fix is kinda hacky.  We return ECONNREFUSED for all non-init
relevant namespaces.  That means that not only will the old broken
non-init_net setups continue to work, now the broken non-init_pid or
non-init_user setups will 'work'.  They don't really work, since audit
isn't logging things.  But it's what most users want.

In 3.15 we should have patches to support not only the non-init_net
(3.14) namespace but also the non-init_pid and non-init_user namespace.
So all will be right in the world.  This just opens the doors wide open
on 3.14 and hopefully makes users happy, if not the audit system...

Reported-by: Andre Tomt <andre@tomt.net>
Reported-by: Adam Richter <adam_richter2004@yahoo.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-03-30 17:02:53 -07:00
John Stultz
cab5e127ee time: Revert to calling clock_was_set_delayed() while in irq context
In commit 47a1b79630 ("tick/timekeeping: Call
update_wall_time outside the jiffies lock"), we moved to calling
clock_was_set() due to the fact that we were no longer holding
the timekeeping or jiffies lock.

However, there is still the problem that clock_was_set()
triggers an IPI, which cannot be done from the timer's hard irq
context, and will generate WARN_ON warnings.

Apparently in my earlier testing, I'm guessing I didn't bump the
dmesg log level, so I somehow missed the WARN_ONs.

Thus we need to revert back to calling clock_was_set_delayed().

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1395963049-11923-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-28 08:07:07 +01:00
Linus Torvalds
f217c44ebd While on my flight to Linux Collaboration Summit, I was working on
my slides for the event trigger tutorial. I booted a 3.14-rc7 kernel
 to perform what I wanted to teach and cut and paste it into my slides.
 When I tried the traceon event trigger with a condition attached to it
 (turns tracing on only if a field of the trigger event matches a condition
 set by the user), nothing happened. Tracing would not turn on. I stopped
 working on my presentation in order to find what was wrong.
 
 It ended up being the way trace event triggers work when they have
 conditions. Instead of copying the fields, the condition code just
 looks at the fields that were copied into the ring buffer. This works
 great, unless tracing is off. That's because when the event is reserved
 on the ring buffer, the ring buffer returns a NULL pointer, this tells
 the tracing code that the ring buffer is disabled. This ends up being
 a problem for the traceon trigger if it is using this information to
 check its condition.
 
 Luckily the code that checks if tracing is on returns the ring buffer
 to use (because the ring buffer is determined by the event file
 also passed to that field). I was able to easily solve this bug by
 checking in that helper function if the returned ring buffer entry
 is NULL, and if so, also check the file flag if it has a trace event
 trigger condition, and if so, to pass back a temp ring buffer to use.
 This will allow the trace event trigger condition to still test the
 event fields, but nothing will be recorded.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJTMtD2AAoJEKQekfcNnQGuwrUH/juk/qKY7T/nq98iMleOD+LR
 iTQyWh9zvHdku/3ZlK5eJqla2TJUctM5Sf9WhvV/iXJ2/9m5qnekZ6gCoraGVpG4
 qfKZAiHdGU0sFdp2NIt1uIHcqjYc8dg2KGajEKGNr7E2F3fvSTfNZV+WKAnmGqlE
 8ICsoYJ/Uv4kh18QQJexbyd7jXWE8tzxxS9UzPvCtCiSd1xf2yCAS5OlwPYafgiv
 Egbjqq7IUCJfVb0h/YfgPbEW69sjlxOulzn42Nii+UOx9uv1RTdtXdivyCXDWfX3
 Que0Do757oTvpW/22s9T3mpUtYLCB+6B2GV+ljqbLCZ5pRywc/GDCU//D1AXKEI=
 =dKWH
 -----END PGP SIGNATURE-----

Merge tag 'trace-fixes-v3.14-rc7-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "While on my flight to Linux Collaboration Summit, I was working on my
  slides for the event trigger tutorial.  I booted a 3.14-rc7 kernel to
  perform what I wanted to teach and cut and paste it into my slides.
  When I tried the traceon event trigger with a condition attached to it
  (turns tracing on only if a field of the trigger event matches a
  condition set by the user), nothing happened.  Tracing would not turn
  on.  I stopped working on my presentation in order to find what was
  wrong.

  It ended up being the way trace event triggers work when they have
  conditions.  Instead of copying the fields, the condition code just
  looks at the fields that were copied into the ring buffer.  This works
  great, unless tracing is off.  That's because when the event is
  reserved on the ring buffer, the ring buffer returns a NULL pointer,
  this tells the tracing code that the ring buffer is disabled.  This
  ends up being a problem for the traceon trigger if it is using this
  information to check its condition.

  Luckily the code that checks if tracing is on returns the ring buffer
  to use (because the ring buffer is determined by the event file also
  passed to that field).  I was able to easily solve this bug by
  checking in that helper function if the returned ring buffer entry is
  NULL, and if so, also check the file flag if it has a trace event
  trigger condition, and if so, to pass back a temp ring buffer to use.
  This will allow the trace event trigger condition to still test the
  event fields, but nothing will be recorded"

* tag 'trace-fixes-v3.14-rc7-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix traceon trigger condition to actually turn tracing on
2014-03-26 09:09:18 -07:00
Steven Rostedt (Red Hat)
2c4a33aba5 tracing: Fix traceon trigger condition to actually turn tracing on
While working on my tutorial for 2014 Linux Collaboration Summit
I found that the traceon trigger did not work when conditions were
used. The other triggers worked fine though. Looking into it, it
is because of the way the triggers use the ring buffer to store
the fields it will use for the condition. But if tracing is off, nothing
is stored in the buffer, and the tracepoint exits before calling the
trigger to test the condition. This is fine for all the triggers that
only work when tracing is on, but for traceon trigger that is to
work when tracing is off, nothing happens.

The fix is simple, just use a temp ring buffer to record the event
if tracing is off and the event has a trace event conditional trigger
enabled. The rest of the tracepoint code will work just fine, but
the tracepoint wont be recorded in the other buffers.

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-25 23:39:41 -04:00
Linus Torvalds
11d4616bd0 futex: revert back to the explicit waiter counting code
Srikar Dronamraju reports that commit b0c29f79ec ("futexes: Avoid
taking the hb->lock if there's nothing to wake up") causes java threads
getting stuck on futexes when runing specjbb on a power7 numa box.

The cause appears to be that the powerpc spinlocks aren't using the same
ticket lock model that we use on x86 (and other) architectures, which in
turn result in the "spin_is_locked()" test in hb_waiters_pending()
occasionally reporting an unlocked spinlock even when there are pending
waiters.

So this reinstates Davidlohr Bueso's original explicit waiter counting
code, which I had convinced Davidlohr to drop in favor of figuring out
the pending waiters by just using the existing state of the spinlock and
the wait queue.

Reported-and-tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Original-code-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-03-20 22:11:17 -07:00
Linus Torvalds
477cc48484 Vaibhav Nagarnaik discovered that since 3.10 a clean up patch made the
array index in the trace event format bogus. He supplied an elegant solution
 that uses __stringify() and also removes the need for the event_storage
 and event_storage_mutex and also cuts off a few K of overhead from
 the trace events.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJTK6cxAAoJEKQekfcNnQGu+3oIAIPGwsevXcVNlmqLwtsoUhu2
 d0uMJYBpi+aQ/stenhkAThzY/5/O0SN2o+uyacSJKDo3WayF9fxGTvOHVbJhvmLF
 YsX6oQLVmzqPrq7BGJTvglv4+RYf+HkV1MAb/1iacA7sFtd7jVpUiPvLlQ3CEwph
 kNqdmoFT16iyE1snUviE0GmZmrdOqZBjwC1Ys+oSbaycRSFnvmDjYAGYot5tJfU5
 gYgpkeJ8J3bxHOGzNCRgmpLQNR3P1HzailPQVi51We14FlzSwOTwuKDtpf8WwzXV
 0fIEkdTU3+K62XxVw5/YQ5o/PpFKO/J5dSPjFe7PF2e6hCTTOABcK5foSSP1KSU=
 =559y
 -----END PGP SIGNATURE-----

Merge tag 'trace-fixes-v3.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull trace fix from Steven Rostedt:
 "Vaibhav Nagarnaik discovered that since 3.10 a clean-up patch made the
  array index in the trace event format bogus.

  He supplied an elegant solution that uses __stringify() and also
  removes the need for the event_storage and event_storage_mutex and
  also cuts off a few K of overhead from the trace events"

* tag 'trace-fixes-v3.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix array size mismatch in format string
2014-03-20 22:09:30 -07:00
Vaibhav Nagarnaik
87291347c4 tracing: Fix array size mismatch in format string
In event format strings, the array size is reported in two locations.
One in array subscript and then via the "size:" attribute. The values
reported there have a mismatch.

For e.g., in sched:sched_switch the prev_comm and next_comm character
arrays have subscript values as [32] where as the actual field size is
16.

name: sched_switch
ID: 301
format:
        field:unsigned short common_type;       offset:0;       size:2; signed:0;
        field:unsigned char common_flags;       offset:2;       size:1; signed:0;
        field:unsigned char common_preempt_count;       offset:3;       size:1;signed:0;
        field:int common_pid;   offset:4;       size:4; signed:1;

        field:char prev_comm[32];       offset:8;       size:16;        signed:1;
        field:pid_t prev_pid;   offset:24;      size:4; signed:1;
        field:int prev_prio;    offset:28;      size:4; signed:1;
        field:long prev_state;  offset:32;      size:8; signed:1;
        field:char next_comm[32];       offset:40;      size:16;        signed:1;
        field:pid_t next_pid;   offset:56;      size:4; signed:1;
        field:int next_prio;    offset:60;      size:4; signed:1;

After bisection, the following commit was blamed:
92edca0 tracing: Use direct field, type and system names

This commit removes the duplication of strings for field->name and
field->type assuming that all the strings passed in
__trace_define_field() are immutable. This is not true for arrays, where
the type string is created in event_storage variable and field->type for
all array fields points to event_storage.

Use __stringify() to create a string constant for the type string.

Also, get rid of event_storage and event_storage_mutex that are not
needed anymore.

also, an added benefit is that this reduces the overhead of events a bit more:

   text    data     bss     dec     hex filename
8424787 2036472 1302528 11763787         b3804b vmlinux
8420814 2036408 1302528 11759750         b37086 vmlinux.patched

Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com

Cc: Laurent Chavey <chavey@google.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-20 13:21:05 -04:00
Linus Torvalds
7c3895383f Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fix from Tejun Heo:
 "One really late cgroup patch to fix error path in create_css().
  Hitting this bug would be pretty rare but still possible and it gets
  delayed we'd need to backport it through -stable anyway.  It only
  updates error path in create_css() and has low chance of new
  breakages"

* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fix a failure path in create_css()
2014-03-19 16:13:40 -07:00
Li Zefan
3eb59ec64f cgroup: fix a failure path in create_css()
If online_css() fails, we should remove cgroup files belonging
to css->ss.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-03-18 17:15:36 -04:00
Linus Torvalds
59bf6c3c6c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Three small fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock: Prevent tracing recursion in sched_clock_cpu()
  stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()
  sched/deadline: Deny unprivileged users to set/change SCHED_DEADLINE policy
2014-03-16 10:42:07 -07:00
Linus Torvalds
adf961d7e8 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull audit namespace fixes from Eric Biederman:
 "Starting with 3.14-rc1 the audit code is faulty (think oopses and
  races) with respect to how it computes the network namespace of which
  socket to reply to, and I happened to notice by chance when reading
  through the code.

  My testing and the automated build bots don't find any problems with
  these fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  audit: Update kdoc for audit_send_reply and audit_list_rules_send
  audit: Send replies in the proper network namespace.
  audit: Use struct net not pid_t to remember the network namespce to reply in
2014-03-11 10:17:50 -07:00
Fernando Luis Vazquez Cao
96b3d28bf4 sched/clock: Prevent tracing recursion in sched_clock_cpu()
Prevent tracing of preempt_disable/enable() in sched_clock_cpu().
When CONFIG_DEBUG_PREEMPT is enabled, preempt_disable/enable() are
traced and this causes trace_clock() users (and probably others) to
go into an infinite recursion. Systems with a stable sched_clock()
are not affected.

This problem is similar to that fixed by upstream commit 95ef1e5292
("KVM guest: prevent tracing recursion with kvmclock").

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1394083528.4524.3.camel@nexus
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-11 11:33:48 +01:00
Peter Zijlstra
177c53d943 stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()
We must use smp_call_function_single(.wait=1) for the
irq_cpu_stop_queue_work() to ensure the queueing is actually done under
stop_cpus_lock. Without this we could have dropped the lock by the time
we do the queueing and get the race we tried to fix.

Fixes: 7053ea1a34 ("stop_machine: Fix race between stop_two_cpus() and stop_cpus()")

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140228123905.GK3104@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-11 11:33:47 +01:00
Juri Lelli
d44753b843 sched/deadline: Deny unprivileged users to set/change SCHED_DEADLINE policy
Deny the use of SCHED_DEADLINE policy to unprivileged users.
Even if root users can set the policy for normal users, we
don't want the latter to be able to change their parameters
(safest behavior).

Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1393844961-18097-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-11 11:33:46 +01:00
Johannes Weiner
e97ca8e5b8 mm: fix GFP_THISNODE callers and clarify
GFP_THISNODE is for callers that implement their own clever fallback to
remote nodes.  It restricts the allocation to the specified node and
does not invoke reclaim, assuming that the caller will take care of it
when the fallback fails, e.g.  through a subsequent allocation request
without GFP_THISNODE set.

However, many current GFP_THISNODE users only want the node exclusive
aspect of the flag, without actually implementing their own fallback or
triggering reclaim if necessary.  This results in things like page
migration failing prematurely even when there is easily reclaimable
memory available, unless kswapd happens to be running already or a
concurrent allocation attempt triggers the necessary reclaim.

Convert all callsites that don't implement their own fallback strategy
to __GFP_THISNODE.  This restricts the allocation a single node too, but
at the same time allows the allocator to enter the slowpath, wake
kswapd, and invoke direct reclaim if necessary, to make the allocation
happen when memory is full.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-03-10 17:26:19 -07:00
Eric W. Biederman
d211f177b2 audit: Update kdoc for audit_send_reply and audit_list_rules_send
The kbuild test robot reported:
> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-next
> head:   6f285b19d0
> commit: 6f285b19d0 [2/2] audit: Send replies in the proper network namespace.
> reproduce: make htmldocs
>
> >> Warning(kernel/audit.c:575): No description found for parameter 'request_skb'
> >> Warning(kernel/audit.c:575): Excess function parameter 'portid' description in 'audit_send_reply'
> >> Warning(kernel/auditfilter.c:1074): No description found for parameter 'request_skb'
> >> Warning(kernel/auditfilter.c:1074): Excess function parameter 'portid' description in 'audit_list_rules_s

Which was caused by my failure to update the kdoc annotations when I
updated the functions.  Fix that small oversight now.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2014-03-08 15:31:54 -08:00
Linus Torvalds
ca62eec4e5 Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
 "Two cpuset locking fixes from Li.  Both tagged for -stable"

* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: fix a race condition in __cpuset_node_allowed_softwall()
  cpuset: fix a locking issue in cpuset_migrate_mm()
2014-03-08 11:57:38 -08:00
Linus Torvalds
721f0c1260 In the past, I've had lots of reports about trace events not working.
Developers would say they put a trace_printk() before and after the trace
 event but when they enable it (and the trace event said it was enabled) they
 would see the trace_printks but not the trace event.
 
 I was not able to reproduce this, but that's because I wasn't looking at
 the right location. Recently, another bug came up that showed the issue.
 
 If your kernel supports signed modules but allows for non-signed modules
 to be loaded, then when one is, the kernel will silently set the
 MODULE_FORCED taint on the module. Although, this taint happens without
 the need for insmod --force or anything of the kind, it labels the
 module with that taint anyway.
 
 If this tainted module has tracepoints, the tracepoints will be ignored
 because of the MODULE_FORCED taint. But no error message will be
 displayed. Worse yet, the event infrastructure will still be created
 letting users enable the trace event represented by the tracepoint,
 although that event will never actually be enabled. This is because
 the tracepoint infrastructure allows for non-existing tracepoints to
 be enabled for new modules to arrive and have their tracepoints set.
 
 Although there are several things wrong with the above, this change
 only addresses the creation of the trace event files for tracepoints
 that are not created when a module is loaded and is tainted. This change
 will print an error message about the module being tainted and not the
 trace events will not be created, and it does not create the trace event
 infrastructure.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJTFnMPAAoJEKQekfcNnQGuPPwH/Rtwy/siM+ltvlLnEbRjS4RL
 9aF5mfJUazmfCaOBMSaMUo92uCbciIVif6icX843JmCdCOR5Hk5SZryBbt2A/dF9
 TcMloKNbIn/ad7yZ0O75BJlPnRJ5RZ42edQfW1lkdeWo644C8Kj399fVPt7KU5SH
 1KTWyShT05E2fYjp2lMrb+FOFfKerlzkXtgGwJKXnd/7hrbdmKEH/OO8YkMrlVZp
 SURPyzNMMVKoUFY797b6FrFRqV04C210BtNcNrd4S3/V9VE4IPS/8YSLfvVaGkD0
 e2kVAvIOkwPnYzMZg70jf2R8NlGS2mwaVC+NenBHz3KlpFdaeRu1hFw7/n8h2/s=
 =YbJd
 -----END PGP SIGNATURE-----

Merge tag 'trace-fixes-v3.14-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "In the past, I've had lots of reports about trace events not working.
  Developers would say they put a trace_printk() before and after the
  trace event but when they enable it (and the trace event said it was
  enabled) they would see the trace_printks but not the trace event.

  I was not able to reproduce this, but that's because I wasn't looking
  at the right location.  Recently, another bug came up that showed the
  issue.

  If your kernel supports signed modules but allows for non-signed
  modules to be loaded, then when one is, the kernel will silently set
  the MODULE_FORCED taint on the module.  Although, this taint happens
  without the need for insmod --force or anything of the kind, it labels
  the module with that taint anyway.

  If this tainted module has tracepoints, the tracepoints will be
  ignored because of the MODULE_FORCED taint.  But no error message will
  be displayed.  Worse yet, the event infrastructure will still be
  created letting users enable the trace event represented by the
  tracepoint, although that event will never actually be enabled.  This
  is because the tracepoint infrastructure allows for non-existing
  tracepoints to be enabled for new modules to arrive and have their
  tracepoints set.

  Although there are several things wrong with the above, this change
  only addresses the creation of the trace event files for tracepoints
  that are not created when a module is loaded and is tainted.  This
  change will print an error message about the module being tainted and
  not the trace events will not be created, and it does not create the
  trace event infrastructure"

* tag 'trace-fixes-v3.14-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Do not add event files for modules that fail tracepoints
2014-03-07 16:32:40 -08:00
Linus Torvalds
27ea0f7811 Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fixes from Thomas Gleixner:
 - a bugfix for a long standing waitqueue race
 - a trivial fix for a missing include

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Include missing header file in irqdomain.c
  genirq: Remove racy waitqueue_active check
2014-03-07 16:31:41 -08:00
Steven Rostedt (Red Hat)
45ab2813d4 tracing: Do not add event files for modules that fail tracepoints
If a module fails to add its tracepoints due to module tainting, do not
create the module event infrastructure in the debugfs directory. As the events
will not work and worse yet, they will silently fail, making the user wonder
why the events they enable do not display anything.

Having a warning on module load and the events not visible to the users
will make the cause of the problem much clearer.

Link: http://lkml.kernel.org/r/20140227154923.265882695@goodmis.org

Fixes: 6d723736e4 "tracing/events: add support for modules to TRACE_EVENT"
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org # 2.6.31+
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-03 21:11:05 -05:00
Linus Torvalds
0c0bd34a14 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Misc fixes, most of them SCHED_DEADLINE fallout"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Prevent rt_time growth to infinity
  sched/deadline: Switch CPU's presence test order
  sched/deadline: Cleanup RT leftovers from {inc/dec}_dl_migration
  sched: Fix double normalization of vruntime
2014-03-03 10:49:24 -08:00
Linus Torvalds
3154da34be Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "Misc fixes, most of them on the tooling side"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf tools: Fix strict alias issue for find_first_bit
  perf tools: fix BFD detection on opensuse
  perf: Fix hotplug splat
  perf/x86: Fix event scheduling
  perf symbols: Destroy unused symsrcs
  perf annotate: Check availability of annotate when processing samples
2014-03-02 11:37:07 -06:00
Eric W. Biederman
6f285b19d0 audit: Send replies in the proper network namespace.
In perverse cases of file descriptor passing the current network
namespace of a process and the network namespace of a socket used by
that socket may differ.  Therefore use the network namespace of the
appropiate socket to ensure replies always go to the appropiate
socket.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2014-02-28 19:44:55 -08:00
Eric W. Biederman
48095d991d audit: Use struct net not pid_t to remember the network namespce to reply in
In struct audit_netlink_list and audit_reply add a reference to the
network namespace of the caller and remove the userspace pid of the
caller.  This cleanly remembers the callers network namespace, and
removes a huge class of races and nasty failure modes that can occur
when attempting to relook up the callers network namespace from a
pid_t (including the caller's network namespace changing, pid
wraparound, and the pid simply not being present).

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2014-02-28 04:04:33 -08:00
Linus Torvalds
8d7531825c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull filesystem fixes from Jan Kara:
 "Notification, writeback, udf, quota fixes

  The notification patches are (with one exception) a fallout of my
  fsnotify rework which went into -rc1 (I've extented LTP to cover these
  cornercases to avoid similar breakage in future).

  The UDF patch is a nasty data corruption Al has recently reported,
  the revert of the writeback patch is due to possibility of violating
  sync(2) guarantees, and a quota bug can lead to corruption of quota
  files in ocfs2"

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: Allocate overflow events with proper type
  fanotify: Handle overflow in case of permission events
  fsnotify: Fix detection whether overflow event is queued
  Revert "writeback: do not sync data dirtied after sync start"
  quota: Fix race between dqput() and dquot_scan_active()
  udf: Fix data corruption on file type conversion
  inotify: Fix reporting of cookies for inotify events
2014-02-27 10:37:22 -08:00
Li Zefan
99afb0fd5f cpuset: fix a race condition in __cpuset_node_allowed_softwall()
It's not safe to access task's cpuset after releasing task_lock().
Holding callback_mutex won't help.

Cc: <stable@vger.kernel.org>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-27 09:39:54 -05:00
Li Zefan
4729583006 cpuset: fix a locking issue in cpuset_migrate_mm()
I can trigger a lockdep warning:

  # mount -t cgroup -o cpuset xxx /cgroup
  # mkdir /cgroup/cpuset
  # mkdir /cgroup/tmp
  # echo 0 > /cgroup/tmp/cpuset.cpus
  # echo 0 > /cgroup/tmp/cpuset.mems
  # echo 1 > /cgroup/tmp/cpuset.memory_migrate
  # echo $$ > /cgroup/tmp/tasks
  # echo 1 > /cgruop/tmp/cpuset.mems

  ===============================
  [ INFO: suspicious RCU usage. ]
  3.14.0-rc1-0.1-default+ #32 Not tainted
  -------------------------------
  include/linux/cgroup.h:682 suspicious rcu_dereference_check() usage!
  ...
    [<ffffffff81582174>] dump_stack+0x72/0x86
    [<ffffffff810b8f01>] lockdep_rcu_suspicious+0x101/0x140
    [<ffffffff81105ba1>] cpuset_migrate_mm+0xb1/0xe0
  ...

We used to hold cgroup_mutex when calling cpuset_migrate_mm(), but now
we hold cpuset_mutex, which causes task_css() to complain.

This is not a false-positive but a real issue.

Holding cpuset_mutex won't prevent a task from migrating to another
cpuset, and it won't prevent the original task->cgroup from destroying
during this change.

Fixes: 5d21cc2db0 (cpuset: replace cgroup_mutex locking with cpuset internal locking)
Cc: <stable@vger.kernel.org> # 3.9+
Signed-off-by: Li Zefan <lizefan@huawei.com>
Sigend-off-by: Tejun Heo <tj@kernel.org>
2014-02-27 09:35:59 -05:00
Rashika Kheria
64be38ab03 genirq: Include missing header file in irqdomain.c
Include appropriate header file include/linux/of_irq.h in
kernel/irq/irqdomain.c because it contains prototype definition of
function define in kernel/irq/irqdomain.c.

This eliminates the following warning in kernel/irq/irqdomain.c:
kernel/irq/irqdomain.c:468:14: warning: no previous prototype for ‘irq_create_of_mapping’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Link: http://lkml.kernel.org/r/eb89aebea7ff1a46122918ac389ebecf8248be9a.1393493276.git.rashika.kheria@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-27 13:29:35 +01:00
Peter Zijlstra
e3703f8cdf perf: Fix hotplug splat
Drew Richardson reported that he could make the kernel go *boom* when hotplugging
while having perf events active.

It turned out that when you have a group event, the code in
__perf_event_exit_context() fails to remove the group siblings from
the context.

We then proceed with destroying and freeing the event, and when you
re-plug the CPU and try and add another event to that CPU, things go
*boom* because you've still got dead entries there.

Reported-by: Drew Richardson <drew.richardson@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-27 12:38:03 +01:00
Juri Lelli
faa5993736 sched/deadline: Prevent rt_time growth to infinity
Kirill Tkhai noted:

  Since deadline tasks share rt bandwidth, we must care about
  bandwidth timer set. Otherwise rt_time may grow up to infinity
  in update_curr_dl(), if there are no other available RT tasks
  on top level bandwidth.

RT task were in fact throttled right after they got enqueued,
and never executed again (rt_time never again went below rt_runtime).

Peter then proposed to accrue DL execution on rt_time only when
rt timer is active, and proposed a patch (this patch is a slight
modification of that) to implement that behavior. While this
solves Kirill problem, it has a drawback.

Indeed, Kirill noted again:

  It looks we may get into a situation, when all CPU time is shared
  between RT and DL tasks:

  rt_runtime = n
  rt_period  = 2n

  | RT working, DL sleeping  | DL working, RT sleeping      |
  -----------------------------------------------------------
  | (1)     duration = n     | (2)     duration = n         | (repeat)
  |--------------------------|------------------------------|
  | (rt_bw timer is running) | (rt_bw timer is not running) |

  No time for fair tasks at all.

While this can happen during the first period, if rq is always backlogged,
RT tasks won't have the opportunity to execute anymore: rt_time reached
rt_runtime during (1), suppose after (2) RT is enqueued back, it gets
throttled since rt timer didn't fire, replenishment is from now on eaten up
by DL tasks that accrue their execution on rt_time (while rt timer is
active - we have an RT task waiting for replenishment). FAIR tasks are
not touched after this first period. Ok, this is not ideal, and the situation
is even worse!

What above (the nice case), practically never happens in reality, where
your rt timer is not aligned to tasks periods, tasks are in general not
periodic, etc.. Long story short, you always risk to overload your system.

This patch is based on Peter's idea, but exploits an additional fact:
if you don't have RT tasks enqueued, it makes little sense to continue
incrementing rt_time once you reached the upper limit (DL tasks have their
own mechanism for throttling).

This cures both problems:

 - no matter how many DL instances in the past, you'll have an rt_time
   slightly above rt_runtime when an RT task is enqueued, and from that
   point on (after the first replenishment), the task will normally execute;

 - you can still eat up all bandwidth during the first period, but not
   anymore after that, remember that DL execution will increment rt_time
   till the upper limit is reached.

The situation is still not perfect! But, we have a simple solution for now,
that limits how much you can jeopardize your system, as we keep working
towards the right answer: RT groups scheduled using deadline servers.

Reported-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20140225151515.617714e2f2cd6c558531ba61@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-27 12:29:41 +01:00
Juri Lelli
eec751ed41 sched/deadline: Switch CPU's presence test order
Commit 82b9580 ("sched/deadline: Test for CPU's presence explicitly")
changed how we check if a CPU returned by cpudeadline machinery is
valid. But, we don't want to call cpu_present() if best_cpu is
equal to -1. So, switch the order of tests inside WARN_ON().

Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: boris.ostrovsky@oracle.com
Cc: konrad.wilk@oracle.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1393238832-9100-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-27 12:29:40 +01:00
Kirill Tkhai
3908ac13b5 sched/deadline: Cleanup RT leftovers from {inc/dec}_dl_migration
In deadline class we do not have group scheduling.

So, let's remove unnecessary

	X = X;

equations.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Link: http://lkml.kernel.org/r/1393343543.4089.5.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-27 12:29:39 +01:00
George McCollister
791c9e0292 sched: Fix double normalization of vruntime
dequeue_entity() is called when p->on_rq and sets se->on_rq = 0
which appears to guarentee that the !se->on_rq condition is met.
If the task has done set_current_state(TASK_INTERRUPTIBLE) without
schedule() the second condition will be met and vruntime will be
incorrectly adjusted twice.

In certain cases this can result in the task's vruntime never increasing
past the vruntime of other tasks on the CFS' run queue, starving them of
CPU time.

This patch changes switched_from_fair() to use !p->on_rq instead of
!se->on_rq.

I'm able to cause a task with a priority of 120 to starve all other
tasks with the same priority on an ARM platform running 3.2.51-rt72
PREEMPT RT by writing one character at time to a serial tty (16550 UART)
in a tight loop. I'm also able to verify making this change corrects the
problem on that platform and kernel version.

Signed-off-by: George McCollister <george.mccollister@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1392767811-28916-1-git-send-email-george.mccollister@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-27 12:29:38 +01:00
Chuansheng Liu
c685689fd2 genirq: Remove racy waitqueue_active check
We hit one rare case below:

T1 calling disable_irq(), but hanging at synchronize_irq()
always;
The corresponding irq thread is in sleeping state;
And all CPUs are in idle state;

After analysis, we found there is one possible scenerio which
causes T1 is waiting there forever:
CPU0                                       CPU1
 synchronize_irq()
  wait_event()
    spin_lock()
                                           atomic_dec_and_test(&threads_active)
      insert the __wait into queue
    spin_unlock()
                                           if(waitqueue_active)
    atomic_read(&threads_active)
                                             wake_up()

Here after inserted the __wait into queue on CPU0, and before
test if queue is empty on CPU1, there is no barrier, it maybe
cause it is not visible for CPU1 immediately, although CPU0 has
updated the queue list.
It is similar for CPU0 atomic_read() threads_active also.

So we'd need one smp_mb() before waitqueue_active.that, but removing
the waitqueue_active() check solves it as wel l and it makes
things simple and clear.

Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Cc: Xiaoming Wang <xiaoming.wang@intel.com>
Link: http://lkml.kernel.org/r/1393212590-32543-1-git-send-email-chuansheng.liu@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-27 10:54:16 +01:00
Linus Torvalds
b2880eb83d Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Thomas Gleixner:
 "Serialize the registration of a new sched_clock in the currently ARM
  only generic sched_clock facilty to avoid sched_clock havoc"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched_clock: Prevent callers from seeing half-updated data
2014-02-23 14:17:08 -08:00
Kirill Tkhai
995b9ea440 sched/deadline: Remove useless dl_nr_total
In deadline class we do not have group scheduling like in RT.

dl_nr_total is the same as dl_nr_running. So, one of them should
be removed.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/368631392675853@web20h.yandex.ru
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Boris Ostrovsky
82b95800b2 sched/deadline: Test for CPU's presence explicitly
A hot-removed CPU may have ID that is numerically larger than the number of
existing CPUs in the system (e.g. we can unplug CPU 4 from a system that
has CPUs 0, 1 and 4).

Thus the WARN_ONs should check whether the CPU in question is currently
present, not whether its ID value is less than num_present_cpus().

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392646353-1874-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Peter Zijlstra
6d35ab4809 sched: Add 'flags' argument to sched_{set,get}attr() syscalls
Because of a recent syscall design debate; its deemed appropriate for
each syscall to have a flags argument for future extension; without
immediately requiring new syscalls.

Cc: juri.lelli@gmail.com
Cc: Ingo Molnar <mingo@redhat.com>
Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140214161929.GL27965@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Vegard Nossum
4efbc454ba sched: Fix information leak in sys_sched_getattr()
We're copying the on-stack structure to userspace, but forgot to give
the right number of bytes to copy. This allows the calling process to
obtain up to PAGE_SIZE bytes from the stack (and possibly adjacent
kernel memory).

This fix copies only as much as we actually have on the stack
(attr->size defaults to the size of the struct) and leaves the rest of
the userspace-provided buffer untouched.

Found using kmemcheck + trinity.

Fixes: d50dde5a10 ("sched: Add new scheduler syscalls to support an extended scheduling parameters ABI")
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392585857-10725-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Rik van Riel
3cf1962cdb sched,numa: add cond_resched to task_numa_work
Normally task_numa_work scans over a fairly small amount of memory,
but it is possible to run into a large unpopulated part of virtual
memory, with no pages mapped. In that case, task_numa_work can run
for a while, and it may make sense to reschedule as required.

Cc: akpm@linux-foundation.org
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Xing Gang <gang.xing@hp.com>
Tested-by: Chegu Vinod <chegu_vinod@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392761566-24834-2-git-send-email-riel@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Juri Lelli
495163420a sched/core: Make dl_b->lock IRQ safe
Fix this lockdep warning:

[   44.804600] =========================================================
[   44.805746] [ INFO: possible irq lock inversion dependency detected ]
[   44.805746] 3.14.0-rc2-test+ #14 Not tainted
[   44.805746] ---------------------------------------------------------
[   44.805746] bash/3674 just changed the state of lock:
[   44.805746]  (&dl_b->lock){+.....}, at: [<ffffffff8106ad15>] sched_rt_handler+0x132/0x248
[   44.805746] but this lock was taken by another, HARDIRQ-safe lock in the past:
[   44.805746]  (&rq->lock){-.-.-.}

and interrupts could create inverse lock ordering between them.

[   44.805746]
[   44.805746] other info that might help us debug this:
[   44.805746]  Possible interrupt unsafe locking scenario:
[   44.805746]
[   44.805746]        CPU0                    CPU1
[   44.805746]        ----                    ----
[   44.805746]   lock(&dl_b->lock);
[   44.805746]                                local_irq_disable();
[   44.805746]                                lock(&rq->lock);
[   44.805746]                                lock(&dl_b->lock);
[   44.805746]   <Interrupt>
[   44.805746]     lock(&rq->lock);

by making dl_b->lock acquiring always IRQ safe.

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392107067-19907-3-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Juri Lelli
e9e7cb38c2 sched/core: Fix sched_rt_global_validate
Don't compare sysctl_sched_rt_runtime against sysctl_sched_rt_period if
the former is equal to RUNTIME_INF, otherwise disabling -rt bandwidth
management (with CONFIG_RT_GROUP_SCHED=n) fails.

Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392107067-19907-2-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:10 +01:00
Steven Rostedt
4df1638cfa sched/deadline: Fix overflow to handle period==0 and deadline!=0
While debugging the crash with the bad nr_running accounting, I hit
another bug where, after running my sched deadline test, I was getting
failures to take a CPU offline. It was giving me a -EBUSY error.

Adding a bunch of trace_printk()s around, I found that the cpu
notifier that called sched_cpu_inactive() was returning a failure. The
overflow value was coming up negative?

Talking this over with Juri, the problem is that the total_bw update was
suppose to be made by dl_overflow() which, during my tests, seemed to
not be called. Adding more trace_printk()s, it wasn't that it wasn't
called, but it exited out right away with the check of new_bw being
equal to p->dl.dl_bw. The new_bw calculates the ratio between period and
runtime. The bug is that if you set a deadline, you do not need to set
a period if you plan on the period being equal to the deadline. That
is, if period is zero and deadline is not, then the system call should
set the period to be equal to the deadline. This is done elsewhere in
the code.

The fix is easy, check if period is set, and if it is not, then use the
deadline.

Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140219135335.7e74abd4@gandalf.local.home
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:09 +01:00
Juri Lelli
3d5f35bdfd sched/deadline: Fix bad accounting of nr_running
Rostedt writes:

My test suite was locking up hard when enabling mmiotracer. This was due
to the mmiotracer placing all but one CPU offline. I found this out
when I was able to reproduce the bug with just my stress-cpu-hotplug
test. This bug baffled me because it would not always trigger, and
would only trigger on the first run after boot up. The
stress-cpu-hotplug test would crash hard the first run, or never crash
at all. But a new reboot may cause it to crash on the first run again.

I spent all week bisecting this, as I couldn't find a consistent
reproducer. I finally narrowed it down to the sched deadline patches,
and even more peculiar, to the commit that added the sched
deadline boot up self test to the latency tracer. Then it dawned on me
to what the bug was.

All it took was to run a task under sched deadline to screw up the CPU
hot plugging. This explained why it would lock up only on the first run
of the stress-cpu-hotplug test. The bug happened when the boot up self
test of the schedule latency tracer would test a deadline task. The
deadline task would corrupt something that would cause CPU hotplug to
fail. If it didn't corrupt it, the stress test would always work
(there's no other sched deadline tasks that would run to cause
problems). If it did corrupt on boot up, the first test would lockup
hard.

I proved this theory by running my deadline test program on another box,
and then run the stress-cpu-hotplug test, and it would now consistently
lock up. I could run stress-cpu-hotplug over and over with no problem,
but once I ran the deadline test, the next run of the
stress-cpu-hotplug would lock hard.

After adding lots of tracing to the code, I found the cause. The
function tracer showed that migrate_tasks() was stuck in an infinite
loop, where rq->nr_running never equaled 1 to break out of it. When I
added a trace_printk() to see what that number was, it was 335 and
never decrementing!

Looking at the deadline code I found:

static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) {
	dequeue_dl_entity(&p->dl);
	dequeue_pushable_dl_task(rq, p);
}

static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) {
	update_curr_dl(rq);
	__dequeue_task_dl(rq, p, flags);

	dec_nr_running(rq);
}

And this:

	if (dl_runtime_exceeded(rq, dl_se)) {
		__dequeue_task_dl(rq, curr, 0);
		if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))
			dl_se->dl_throttled = 1;
		else
			enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);

		if (!is_leftmost(curr, &rq->dl))
			resched_task(curr);
	}

Notice how we call __dequeue_task_dl() and in the else case we
call enqueue_task_dl()? Also notice that dequeue_task_dl() has
underscores where enqueue_task_dl() does not. The enqueue_task_dl()
calls inc_nr_running(rq), but __dequeue_task_dl() does not. This is
where we get nr_running out of sync.

[snip]

Another point where nr_running can get out of sync is when the dl_timer
fires:

	dl_se->dl_throttled = 0;
	if (p->on_rq) {
		enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
		if (task_has_dl_policy(rq->curr))
			check_preempt_curr_dl(rq, p, 0);
		else
			resched_task(rq->curr);

This patch does two things:

 - correctly accounts for throttled tasks (that are now considered
   !running);

 - fixes the bug, updating nr_running from {inc,dec}_dl_tasks(),
   since we risk to update it twice in some situations (e.g., a
   task is dequeued while it has exceeded its budget).

Cc: mingo@redhat.com
Cc: torvalds@linux-foundation.org
Cc: akpm@linux-foundation.org
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392884379-13744-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21 21:27:09 +01:00
Linus Torvalds
6a4d07f85b Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
 "Quite a few fixes this time.

  Three locking fixes, all marked for -stable.  A couple error path
  fixes and some misc fixes.  Hugh found a bug in memcg offlining
  sequence and we thought we could fix that from cgroup core side but
  that turned out to be insufficient and got reverted.  A different fix
  has been applied to -mm"

* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: update cgroup_enable_task_cg_lists() to grab siglock
  Revert "cgroup: use an ordered workqueue for cgroup destruction"
  cgroup: protect modifications to cgroup_idr with cgroup_mutex
  cgroup: fix locking in cgroup_cfts_commit()
  cgroup: fix error return from cgroup_create()
  cgroup: fix error return value in cgroup_mount()
  cgroup: use an ordered workqueue for cgroup destruction
  nfs: include xattr.h from fs/nfs/nfs3proc.c
  cpuset: update MAINTAINERS entry
  arm, pm, vmpressure: add missing slab.h includes
2014-02-20 12:01:09 -08:00
Linus Torvalds
2b73d207a5 Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo:
 "Two workqueue fixes.  One for an unlikely but possible critical bug
  during kworker shutdown and the other to make lockdep names a bit more
  descriptive"

* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: ensure @task is valid across kthread_stop()
  workqueue: add args to workqueue lockdep name
2014-02-20 12:00:27 -08:00
Brian Campbell
b080e047a6 user_namespace.c: Remove duplicated word in comment
Signed-off-by: Brian Campbell <brian.campbell@editshare.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-02-20 11:58:35 -08:00
Stephen Boyd
5ae8aabeae sched_clock: Prevent callers from seeing half-updated data
The generic sched_clock registration function was previously
done lockless, due to the fact that it was expected to be called
only once. However, now there are systems that may register
multiple sched_clock sources, for which the lack of locking has
casued problems:

If two sched_clock sources are registered we may end up in a
situation where a call to sched_clock() may be accessing the
epoch cycle count for the old counter and the cycle count for the
new counter. This can lead to confusing results where
sched_clock() values jump and then are reset to 0 (due to the way
the registration function forces the epoch_ns to be 0).

Fix this by reorganizing the registration function to hold the
seqlock for as short a time as possible while we update the
clock_data structure for a new counter. We also put any
accumulated time into epoch_ns instead of resetting the time to
0 so that the clock doesn't reset after each successful
registration.

[jstultz: Added extra context to the commit message]

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-19 17:07:22 +01:00
Tejun Heo
532de3fc72 cgroup: update cgroup_enable_task_cg_lists() to grab siglock
Currently, there's nothing preventing cgroup_enable_task_cg_lists()
from missing set PF_EXITING and race against cgroup_exit().  Depending
on the timing, cgroup_exit() may finish with the task still linked on
css_set leading to list corruption.  Fix it by grabbing siglock in
cgroup_enable_task_cg_lists() so that PF_EXITING is guaranteed to be
visible.

This whole on-demand cg_list optimization is extremely fragile and has
ample possibility to lead to bugs which can cause things like
once-a-year oops during boot.  I'm wondering whether the better
approach would be just adding "cgroup_disable=all" handling which
disables the whole cgroup rather than tempting fate with this
on-demand craziness.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
2014-02-18 18:23:18 -05:00
Lai Jiangshan
5bdfff96c6 workqueue: ensure @task is valid across kthread_stop()
When a kworker should die, the kworkre is notified through WORKER_DIE
flag instead of kthread_should_stop().  This, IIRC, is primarily to
keep the test synchronized inside worker_pool lock.  WORKER_DIE is
first set while holding pool->lock, the lock is dropped and
kthread_stop() is called.

Unfortunately, this means that there's a slight chance that the target
kworker may see WORKER_DIE before kthread_stop() finishes and exits
and frees the target task before or during kthread_stop().

Fix it by pinning the target task before setting WORKER_DIE and
putting it after kthread_stop() is done.

tj: Improved patch description and comment.  Moved pinning above
    WORKER_DIE for better signify what it's protecting.

CC: stable@vger.kernel.org
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-18 16:35:20 -05:00