Commit Graph

22639 Commits

Author SHA1 Message Date
Steve Muckle
5cbea46984 cpufreq: schedutil: map raw required frequency to driver frequency
The slow-path frequency transition path is relatively expensive as it
requires waking up a thread to do work. Should support be added for
remote CPU cpufreq updates that is also expensive since it requires an
IPI. These activities should be avoided if they are not necessary.

To that end, calculate the actual driver-supported frequency required by
the new utilization value in schedutil by using the recently added
cpufreq_driver_resolve_freq API. If it is the same as the previously
requested driver frequency then there is no need to continue with the
update assuming the cpu frequency limits have not changed. This will
have additional benefits should the semantics of the rate limit be
changed to apply solely to frequency transitions rather than to
frequency calculations in schedutil.

The last raw required frequency is cached. This allows the driver
frequency lookup to be skipped in the event that the new raw required
frequency matches the last one, assuming a frequency update has not been
forced due to limits changing (indicated by a next_freq value of
UINT_MAX, see sugov_should_update_freq).

Signed-off-by: Steve Muckle <smuckle@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-21 22:28:21 +02:00
Rafael J. Wysocki
5d1191ab6c Merge back earlier cpufreq material for v4.8. 2016-07-04 13:21:43 +02:00
Linus Torvalds
57801c1b81 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
 "A couple of scheduler fixes:

   - force watchdog reset while processing sysrq-w

   - fix a deadlock when enabling trace events in the scheduler

   - fixes to the throttled next buddy logic

   - fixes for the average accounting (missing serialization and
     underflow handling)

   - allow kernel threads for fallback to online but not active cpus"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Allow kthreads to fall back to online && !active cpus
  sched/fair: Do not announce throttled next buddy in dequeue_task_fair()
  sched/fair: Initialize throttle_count for new task-groups lazily
  sched/fair: Fix cfs_rq avg tracking underflow
  kernel/sysrq, watchdog, sched/core: Reset watchdog on all CPUs while processing sysrq-w
  sched/debug: Fix deadlock when enabling sched events
  sched/fair: Fix post_init_entity_util_avg() serialization
2016-06-25 06:38:42 -07:00
Linus Torvalds
e3b22bc3d7 Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Thomas Gleixner:
 "A single fix to address a race in the static key logic"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/static_key: Fix concurrent static_key_slow_inc()
2016-06-25 06:14:44 -07:00
Michael Ellerman
9521d39976 Fix build break in fork.c when THREAD_SIZE < PAGE_SIZE
Commit b235beea9e ("Clarify naming of thread info/stack allocators")
breaks the build on some powerpc configs, where THREAD_SIZE < PAGE_SIZE:

  kernel/fork.c:235:2: error: implicit declaration of function 'free_thread_stack'
  kernel/fork.c:355:8: error: assignment from incompatible pointer type
    stack = alloc_thread_stack_node(tsk, node);
    ^

Fix it by renaming free_stack() to free_thread_stack(), and updating the
return type of alloc_thread_stack_node().

Fixes: b235beea9e ("Clarify naming of thread info/stack allocators")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-25 06:01:28 -07:00
Linus Torvalds
086e3eb65e Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton:
 "Two weeks worth of fixes here"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (41 commits)
  init/main.c: fix initcall_blacklisted on ia64, ppc64 and parisc64
  autofs: don't get stuck in a loop if vfs_write() returns an error
  mm/page_owner: avoid null pointer dereference
  tools/vm/slabinfo: fix spelling mistake: "Ocurrences" -> "Occurrences"
  fs/nilfs2: fix potential underflow in call to crc32_le
  oom, suspend: fix oom_reaper vs. oom_killer_disable race
  ocfs2: disable BUG assertions in reading blocks
  mm, compaction: abort free scanner if split fails
  mm: prevent KASAN false positives in kmemleak
  mm/hugetlb: clear compound_mapcount when freeing gigantic pages
  mm/swap.c: flush lru pvecs on compound page arrival
  memcg: css_alloc should return an ERR_PTR value on error
  memcg: mem_cgroup_migrate() may be called with irq disabled
  hugetlb: fix nr_pmds accounting with shared page tables
  Revert "mm: disable fault around on emulated access bit architecture"
  Revert "mm: make faultaround produce old ptes"
  mailmap: add Boris Brezillon's email
  mailmap: add Antoine Tenart's email
  mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim mask
  mm: mempool: kasan: don't poot mempool objects in quarantine
  ...
2016-06-24 19:08:33 -07:00
Michal Hocko
7407054209 oom, suspend: fix oom_reaper vs. oom_killer_disable race
Tetsuo has reported the following potential oom_killer_disable vs.
oom_reaper race:

 (1) freeze_processes() starts freezing user space threads.
 (2) Somebody (maybe a kenrel thread) calls out_of_memory().
 (3) The OOM killer calls mark_oom_victim() on a user space thread
     P1 which is already in __refrigerator().
 (4) oom_killer_disable() sets oom_killer_disabled = true.
 (5) P1 leaves __refrigerator() and enters do_exit().
 (6) The OOM reaper calls exit_oom_victim(P1) before P1 can call
     exit_oom_victim(P1).
 (7) oom_killer_disable() returns while P1 not yet finished
 (8) P1 perform IO/interfere with the freezer.

This situation is unfortunate.  We cannot move oom_killer_disable after
all the freezable kernel threads are frozen because the oom victim might
depend on some of those kthreads to make a forward progress to exit so
we could deadlock.  It is also far from trivial to teach the oom_reaper
to not call exit_oom_victim() because then we would lose a guarantee of
the OOM killer and oom_killer_disable forward progress because
exit_mm->mmput might block and never call exit_oom_victim.

It seems the easiest way forward is to workaround this race by calling
try_to_freeze_tasks again after oom_killer_disable.  This will make sure
that all the tasks are frozen or it bails out.

Fixes: 449d777d7a ("mm, oom_reaper: clear TIF_MEMDIE for all tasks queued for oom_reaper")
Link: http://lkml.kernel.org/r/1466597634-16199-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24 17:23:52 -07:00
Linus Torvalds
b235beea9e Clarify naming of thread info/stack allocators
We've had the thread info allocated together with the thread stack for
most architectures for a long time (since the thread_info was split off
from the task struct), but that is about to change.

But the patches that move the thread info to be off-stack (and a part of
the task struct instead) made it clear how confused the allocator and
freeing functions are.

Because the common case was that we share an allocation with the thread
stack and the thread_info, the two pointers were identical.  That
identity then meant that we would have things like

	ti = alloc_thread_info_node(tsk, node);
	...
	tsk->stack = ti;

which certainly _worked_ (since stack and thread_info have the same
value), but is rather confusing: why are we assigning a thread_info to
the stack? And if we move the thread_info away, the "confusing" code
just gets to be entirely bogus.

So remove all this confusion, and make it clear that we are doing the
stack allocation by renaming and clarifying the function names to be
about the stack.  The fact that the thread_info then shares the
allocation is an implementation detail, and not really about the
allocation itself.

This is a pure renaming and type fix: we pass in the same pointer, it's
just that we clarify what the pointer means.

The ia64 code that actually only has one single allocation (for all of
task_struct, thread_info and kernel thread stack) now looks a bit odd,
but since "tsk->stack" is actually not even used there, that oddity
doesn't matter.  It would be a separate thing to clean that up, I
intentionally left the ia64 changes as a pure brute-force renaming and
type change.

Acked-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24 15:09:37 -07:00
Tejun Heo
feb245e304 sched/core: Allow kthreads to fall back to online && !active cpus
During CPU hotplug, CPU_ONLINE callbacks are run while the CPU is
online but not active.  A CPU_ONLINE callback may create or bind a
kthread so that its cpus_allowed mask only allows the CPU which is
being brought online.  The kthread may start executing before the CPU
is made active and can end up in select_fallback_rq().

In such cases, the expected behavior is selecting the CPU which is
coming online; however, because select_fallback_rq() only chooses from
active CPUs, it determines that the task doesn't have any viable CPU
in its allowed mask and ends up overriding it to cpu_possible_mask.

CPU_ONLINE callbacks should be able to put kthreads on the CPU which
is coming online.  Update select_fallback_rq() so that it follows
cpu_online() rather than cpu_active() for kthreads.

Reported-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160616193504.GB3262@mtj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24 08:26:53 +02:00
Konstantin Khlebnikov
754bd598be sched/fair: Do not announce throttled next buddy in dequeue_task_fair()
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 <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24 08:26:45 +02:00
Konstantin Khlebnikov
094f469172 sched/fair: Initialize throttle_count for new task-groups lazily
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 <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24 08:26:44 +02:00
Paolo Bonzini
4c5ea0a9cd locking/static_key: Fix concurrent static_key_slow_inc()
The following scenario is possible:

    CPU 1                                   CPU 2
    static_key_slow_inc()
     atomic_inc_not_zero()
      -> key.enabled == 0, no increment
     jump_label_lock()
     atomic_inc_return()
      -> key.enabled == 1 now
                                            static_key_slow_inc()
                                             atomic_inc_not_zero()
                                              -> key.enabled == 1, inc to 2
                                             return
                                            ** static key is wrong!
     jump_label_update()
     jump_label_unlock()

Testing the static key at the point marked by (**) will follow the
wrong path for jumps that have not been patched yet.  This can
actually happen when creating many KVM virtual machines with userspace
LAPIC emulation; just run several copies of the following program:

    #include <fcntl.h>
    #include <unistd.h>
    #include <sys/ioctl.h>
    #include <linux/kvm.h>

    int main(void)
    {
        for (;;) {
            int kvmfd = open("/dev/kvm", O_RDONLY);
            int vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0);
            close(ioctl(vmfd, KVM_CREATE_VCPU, 1));
            close(vmfd);
            close(kvmfd);
        }
        return 0;
    }

Every KVM_CREATE_VCPU ioctl will attempt a static_key_slow_inc() call.
The static key's purpose is to skip NULL pointer checks and indeed one
of the processes eventually dereferences NULL.

As explained in the commit that introduced the bug:

  706249c222 ("locking/static_keys: Rework update logic")

jump_label_update() needs key.enabled to be true.  The solution adopted
here is to temporarily make key.enabled == -1, and use go down the
slow path when key.enabled <= 0.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v4.3+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 706249c222 ("locking/static_keys: Rework update logic")
Link: http://lkml.kernel.org/r/1466527937-69798-1-git-send-email-pbonzini@redhat.com
[ Small stylistic edits to the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24 08:23:16 +02:00
Linus Torvalds
6720a305df locking: avoid passing around 'thread_info' in mutex debugging code
None of the code actually wants a thread_info, it all wants a
task_struct, and it's just converting back and forth between the two
("ti->task" to get the task_struct from the thread_info, and
"task_thread_info(task)" to go the other way).

No semantic change.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-23 12:11:17 -07:00
Linus Torvalds
f780f00d72 Two fixes for the tracing system.
o When trace_printk() is used with a non constant format descriptor,
    it adds a NULL pointer into the trace format section, and the code
    isn't prepared to deal with it. This bug appeared by a change that
    was added in v3.5.
 
  o The ftracetest (selftests section) can't handle testing histograms
    when histograms are not configured. Currently it shows that they
    fail the test, when they should state that they are unsupported.
    This bug was added in the 4.7 merge window with the addition of
    the historgram code.
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Merge tag 'trace-v4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Two fixes for the tracing system:

   - When trace_printk() is used with a non constant format descriptor,
     it adds a NULL pointer into the trace format section, and the code
     isn't prepared to deal with it.  This bug appeared by a change that
     was added in v3.5.

   - The ftracetest (selftests section) can't handle testing histograms
     when histograms are not configured.  Currently it shows that they
     fail the test, when they should state that they are unsupported.
     This bug was added in the 4.7 merge window with the addition of the
     historgram code"

* tag 'trace-v4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftracetest: Fix hist unsupported result in hist selftests
  tracing: Handle NULL formats in hold_module_trace_bprintk_format()
2016-06-20 10:35:48 -07:00
Steven Rostedt (Red Hat)
70c8217acd tracing: Handle NULL formats in hold_module_trace_bprintk_format()
If a task uses a non constant string for the format parameter in
trace_printk(), then the trace_printk_fmt variable is set to NULL. This
variable is then saved in the __trace_printk_fmt section.

The function hold_module_trace_bprintk_format() checks to see if duplicate
formats are used by modules, and reuses them if so (saves them to the list
if it is new). But this function calls lookup_format() that does a strcmp()
to the value (which is now NULL) and can cause a kernel oops.

This wasn't an issue till 3debb0a9dd ("tracing: Fix trace_printk() to print
when not using bprintk()") which added "__used" to the trace_printk_fmt
variable, and before that, the kernel simply optimized it out (no NULL value
was saved).

The fix is simply to handle the NULL pointer in lookup_format() and have the
caller ignore the value if it was NULL.

Link: http://lkml.kernel.org/r/1464769870-18344-1-git-send-email-zhengjun.xing@intel.com

Reported-by: xingzhen <zhengjun.xing@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Fixes: 3debb0a9dd ("tracing: Fix trace_printk() to print when not using bprintk()")
Cc: stable@vger.kernel.org # v3.5+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-06-20 09:46:12 -04:00
Peter Zijlstra
8974189222 sched/fair: Fix cfs_rq avg tracking underflow
As per commit:

  b7fa30c9cc ("sched/fair: Fix post_init_entity_util_avg() serialization")

> the code generated from update_cfs_rq_load_avg():
>
> 	if (atomic_long_read(&cfs_rq->removed_load_avg)) {
> 		s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
> 		sa->load_avg = max_t(long, sa->load_avg - r, 0);
> 		sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
> 		removed_load = 1;
> 	}
>
> turns into:
>
> ffffffff81087064:       49 8b 85 98 00 00 00    mov    0x98(%r13),%rax
> ffffffff8108706b:       48 85 c0                test   %rax,%rax
> ffffffff8108706e:       74 40                   je     ffffffff810870b0 <update_blocked_averages+0xc0>
> ffffffff81087070:       4c 89 f8                mov    %r15,%rax
> ffffffff81087073:       49 87 85 98 00 00 00    xchg   %rax,0x98(%r13)
> ffffffff8108707a:       49 29 45 70             sub    %rax,0x70(%r13)
> ffffffff8108707e:       4c 89 f9                mov    %r15,%rcx
> ffffffff81087081:       bb 01 00 00 00          mov    $0x1,%ebx
> ffffffff81087086:       49 83 7d 70 00          cmpq   $0x0,0x70(%r13)
> ffffffff8108708b:       49 0f 49 4d 70          cmovns 0x70(%r13),%rcx
>
> Which you'll note ends up with sa->load_avg -= r in memory at
> ffffffff8108707a.

So I _should_ have looked at other unserialized users of ->load_avg,
but alas. Luckily nikbor reported a similar /0 from task_h_load() which
instantly triggered recollection of this here problem.

Aside from the intermediate value hitting memory and causing problems,
there's another problem: the underflow detection relies on the signed
bit. This reduces the effective width of the variables, IOW its
effectively the same as having these variables be of signed type.

This patch changes to a different means of unsigned underflow
detection to not rely on the signed bit. This allows the variables to
use the 'full' unsigned range. And it does so with explicit LOAD -
STORE to ensure any intermediate value will never be visible in
memory, allowing these unserialized loads.

Note: GCC generates crap code for this, might warrant a look later.

Note2: I say 'full' above, if we end up at U*_MAX we'll still explode;
       maybe we should do clamping on add too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: bsegall@google.com
Cc: kernel@kyup.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: steve.muckle@linaro.org
Fixes: 9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")
Link: http://lkml.kernel.org/r/20160617091948.GJ30927@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-20 11:29:09 +02:00
Nicolai Stange
df4565f9eb kernel/kcov: unproxify debugfs file's fops
Since commit 49d200deaa ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.

However, only a certain subset of the file_operations members is supported
by debugfs and ->mmap isn't among them -- it appears to be NULL from the
VFS layer's perspective.

This behaviour breaks the /sys/kernel/debug/kcov file introduced
concurrently with commit 5c9a8750a6 ("kernel: add kcov code coverage").

Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.

Avoid the proxying for /sys/kernel/debug/kcov by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().

Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Fixes: 5c9a8750a6 ("kernel: add kcov code coverage")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-06-15 04:56:35 -07:00
Andrey Ryabinin
57675cb976 kernel/sysrq, watchdog, sched/core: Reset watchdog on all CPUs while processing sysrq-w
Lengthy output of sysrq-w may take a lot of time on slow serial console.

Currently we reset NMI-watchdog on the current CPU to avoid spurious
lockup messages. Sometimes this doesn't work since softlockup watchdog
might trigger on another CPU which is waiting for an IPI to proceed.
We reset softlockup watchdogs on all CPUs, but we do this only after
listing all tasks, and this may be too late on a busy system.

So, reset watchdogs CPUs earlier, in for_each_process_thread() loop.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1465474805-14641-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14 12:48:38 +02:00
Josh Poimboeuf
eda8dca519 sched/debug: Fix deadlock when enabling sched events
I see a hang when enabling sched events:

  echo 1 > /sys/kernel/debug/tracing/events/sched/enable

The printk buffer shows:

  BUG: spinlock recursion on CPU#1, swapper/1/0
   lock: 0xffff88007d5d8c00, .magic: dead4ead, .owner: swapper/1/0, .owner_cpu: 1
  CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.7.0-rc2+ #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
  ...
  Call Trace:
   <IRQ>  [<ffffffff8143d663>] dump_stack+0x85/0xc2
   [<ffffffff81115948>] spin_dump+0x78/0xc0
   [<ffffffff81115aea>] do_raw_spin_lock+0x11a/0x150
   [<ffffffff81891471>] _raw_spin_lock+0x61/0x80
   [<ffffffff810e5466>] ? try_to_wake_up+0x256/0x4e0
   [<ffffffff810e5466>] try_to_wake_up+0x256/0x4e0
   [<ffffffff81891a0a>] ? _raw_spin_unlock_irqrestore+0x4a/0x80
   [<ffffffff810e5705>] wake_up_process+0x15/0x20
   [<ffffffff810cebb4>] insert_work+0x84/0xc0
   [<ffffffff810ced7f>] __queue_work+0x18f/0x660
   [<ffffffff810cf9a6>] queue_work_on+0x46/0x90
   [<ffffffffa00cd95b>] drm_fb_helper_dirty.isra.11+0xcb/0xe0 [drm_kms_helper]
   [<ffffffffa00cdac0>] drm_fb_helper_sys_imageblit+0x30/0x40 [drm_kms_helper]
   [<ffffffff814babcd>] soft_cursor+0x1ad/0x230
   [<ffffffff814ba379>] bit_cursor+0x649/0x680
   [<ffffffff814b9d30>] ? update_attr.isra.2+0x90/0x90
   [<ffffffff814b5e6a>] fbcon_cursor+0x14a/0x1c0
   [<ffffffff81555ef8>] hide_cursor+0x28/0x90
   [<ffffffff81558b6f>] vt_console_print+0x3bf/0x3f0
   [<ffffffff81122c63>] call_console_drivers.constprop.24+0x183/0x200
   [<ffffffff811241f4>] console_unlock+0x3d4/0x610
   [<ffffffff811247f5>] vprintk_emit+0x3c5/0x610
   [<ffffffff81124bc9>] vprintk_default+0x29/0x40
   [<ffffffff811e965b>] printk+0x57/0x73
   [<ffffffff810f7a9e>] enqueue_entity+0xc2e/0xc70
   [<ffffffff810f7b39>] enqueue_task_fair+0x59/0xab0
   [<ffffffff8106dcd9>] ? kvm_sched_clock_read+0x9/0x20
   [<ffffffff8103fb39>] ? sched_clock+0x9/0x10
   [<ffffffff810e3fcc>] activate_task+0x5c/0xa0
   [<ffffffff810e4514>] ttwu_do_activate+0x54/0xb0
   [<ffffffff810e5cea>] sched_ttwu_pending+0x7a/0xb0
   [<ffffffff810e5e51>] scheduler_ipi+0x61/0x170
   [<ffffffff81059e7f>] smp_trace_reschedule_interrupt+0x4f/0x2a0
   [<ffffffff81893ba6>] trace_reschedule_interrupt+0x96/0xa0
   <EOI>  [<ffffffff8106e0d6>] ? native_safe_halt+0x6/0x10
   [<ffffffff8110fb1d>] ? trace_hardirqs_on+0xd/0x10
   [<ffffffff81040ac0>] default_idle+0x20/0x1a0
   [<ffffffff8104147f>] arch_cpu_idle+0xf/0x20
   [<ffffffff81102f8f>] default_idle_call+0x2f/0x50
   [<ffffffff8110332e>] cpu_startup_entry+0x37e/0x450
   [<ffffffff8105af70>] start_secondary+0x160/0x1a0

Note the hang only occurs when echoing the above from a physical serial
console, not from an ssh session.

The bug is caused by a deadlock where the task is trying to grab the rq
lock twice because printk()'s aren't safe in sched code.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/20160613073209.gdvdybiruljbkn3p@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14 12:47:21 +02:00
Peter Zijlstra
b7fa30c9cc sched/fair: Fix post_init_entity_util_avg() serialization
Chris Wilson reported a divide by 0 at:

 post_init_entity_util_avg():

 >    725	if (cfs_rq->avg.util_avg != 0) {
 >    726		sa->util_avg  = cfs_rq->avg.util_avg * se->load.weight;
 > -> 727		sa->util_avg /= (cfs_rq->avg.load_avg + 1);
 >    728
 >    729		if (sa->util_avg > cap)
 >    730			sa->util_avg = cap;
 >    731	} else {

Which given the lack of serialization, and the code generated from
update_cfs_rq_load_avg() is entirely possible:

	if (atomic_long_read(&cfs_rq->removed_load_avg)) {
		s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
		sa->load_avg = max_t(long, sa->load_avg - r, 0);
		sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
		removed_load = 1;
	}

turns into:

  ffffffff81087064:       49 8b 85 98 00 00 00    mov    0x98(%r13),%rax
  ffffffff8108706b:       48 85 c0                test   %rax,%rax
  ffffffff8108706e:       74 40                   je     ffffffff810870b0
  ffffffff81087070:       4c 89 f8                mov    %r15,%rax
  ffffffff81087073:       49 87 85 98 00 00 00    xchg   %rax,0x98(%r13)
  ffffffff8108707a:       49 29 45 70             sub    %rax,0x70(%r13)
  ffffffff8108707e:       4c 89 f9                mov    %r15,%rcx
  ffffffff81087081:       bb 01 00 00 00          mov    $0x1,%ebx
  ffffffff81087086:       49 83 7d 70 00          cmpq   $0x0,0x70(%r13)
  ffffffff8108708b:       49 0f 49 4d 70          cmovns 0x70(%r13),%rcx

Which you'll note ends up with 'sa->load_avg - r' in memory at
ffffffff8108707a.

By calling post_init_entity_util_avg() under rq->lock we're sure to be
fully serialized against PELT updates and cannot observe intermediate
state like this.

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: bsegall@google.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: steve.muckle@linaro.org
Fixes: 2b8c41daba ("sched/fair: Initiate a new task's util avg to a bounded value")
Link: http://lkml.kernel.org/r/20160609130750.GQ30909@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14 10:58:34 +02:00
Rafael J. Wysocki
bb4b9933e2 Merge back earlier cpufreq changes for v4.8. 2016-06-13 23:33:17 +02:00
Linus Torvalds
f5364c150a Merge branch 'stacking-fixes' (vfs stacking fixes from Jann)
Merge filesystem stacking fixes from Jann Horn.

* emailed patches from Jann Horn <jannh@google.com>:
  sched: panic on corrupted stack end
  ecryptfs: forbid opening files without mmap handler
  proc: prevent stacking filesystems on top
2016-06-10 12:10:02 -07:00
Jann Horn
29d6455178 sched: panic on corrupted stack end
Until now, hitting this BUG_ON caused a recursive oops (because oops
handling involves do_exit(), which calls into the scheduler, which in
turn raises an oops), which caused stuff below the stack to be
overwritten until a panic happened (e.g.  via an oops in interrupt
context, caused by the overwritten CPU index in the thread_info).

Just panic directly.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-10 12:09:43 -07:00
Linus Torvalds
60e383037b Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Two scheduler debugging fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/debug: Fix 'schedstats=enable' cmdline option
  sched/debug: Fix /proc/sched_debug regression
2016-06-10 11:24:39 -07:00
Linus Torvalds
7fcbc230c6 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "A handful of tooling fixes, two PMU driver fixes and a cleanup of
  redundant code that addresses a security analyzer false positive"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Remove a redundant check
  perf/x86/intel/uncore: Remove SBOX support for Broadwell server
  perf ctf: Convert invalid chars in a string before set value
  perf record: Fix crash when kptr is restricted
  perf symbols: Check kptr_restrict for root
  perf/x86/intel/rapl: Fix pmus free during cleanup
2016-06-10 11:15:41 -07:00
Linus Torvalds
02b07bde61 Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
 "Misc fixes:

   - a file-based futex fix
   - one more spin_unlock_wait() fix
   - a ww-mutex deadlock detection improvement/fix
   - and a raw_read_seqcount_latch() barrier fix"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Calculate the futex key based on a tail page for file-based futexes
  locking/qspinlock: Fix spin_unlock_wait() some more
  locking/ww_mutex: Report recursive ww_mutex locking early
  locking/seqcount: Re-fix raw_read_seqcount_latch()
2016-06-10 10:53:46 -07:00
Linus Torvalds
698ea54dde Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Pull networking fixes from David Miller:

 1) nfnetlink timestamp taken from wrong skb, fix from Florian Westphal.

 2) Revert some msleep conversions in rtlwifi as these spots are in
    atomic context, from Larry Finger.

 3) Validate that NFTA_SET_TABLE attribute is actually specified when we
    call nf_tables_getset().  From Phil Turnbull.

 4) Don't do mdio_reset in stmmac driver with spinlock held as that can
    sleep, from Vincent Palatin.

 5) sk_filter() does things other than run a BPF filter, so we should
    not elide it's call just because sk->sk_filter is NULL.  Fix from
    Eric Dumazet.

 6) Fix missing backlog updates in several packet schedulers, from Cong
    Wang.

 7) bnx2x driver should allow VLAN add/remove while the interface is
    down, from Michal Schmidt.

 8) Several RDS/TCP race fixes from Sowmini Varadhan.

 9) fq_codel scheduler doesn't return correct queue length in dumps,
    from Eric Dumazet.

10) Fix TCP stats for tail loss probe and early retransmit in ipv6, from
    Yuchung Cheng.

11) Properly initialize udp_tunnel_socket_cfg in l2tp_tunnel_create(),
    from Guillaume Nault.

12) qfq scheduler leaks SKBs if a kzalloc fails, fix from Florian
    Westphal.

13) sock_fprog passed into PACKET_FANOUT_DATA needs compat handling,
    from Willem de Bruijn.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (85 commits)
  vmxnet3: segCnt can be 1 for LRO packets
  packet: compat support for sock_fprog
  stmmac: fix parameter to dwmac4_set_umac_addr()
  net/mlx5e: Fix blue flame quota logic
  net/mlx5e: Use ndo_stop explicitly at shutdown flow
  net/mlx5: E-Switch, always set mc_promisc for allmulti vports
  net/mlx5: E-Switch, Modify node guid on vf set MAC
  net/mlx5: E-Switch, Fix vport enable flow
  net/mlx5: E-Switch, Use the correct error check on returned pointers
  net/mlx5: E-Switch, Use the correct free() function
  net/mlx5: Fix E-Switch flow steering capabilities check
  net/mlx5: Fix flow steering NIC capabilities check
  net/mlx5: Fix root flow table update
  net/mlx5: Fix MLX5_CMD_OP_MAX to be defined correctly
  net/mlx5: Fix masking of reserved bits in XRCD number
  net/mlx5: Fix the size of modify QP mailbox
  mlxsw: spectrum: Don't sleep during ndo_get_phys_port_name()
  mlxsw: spectrum: Make split flow match firmware requirements
  wext: Fix 32 bit iwpriv compatibility issue with 64 bit Kernel
  cfg80211: remove get/set antenna and tx power warnings
  ...
2016-06-10 08:32:24 -07:00
Linus Torvalds
524a3f2ca2 Power management fixes for v4.7-rc3
- Fix two intel_pstate initialization issues, one of which was
    introduced during the 4.4 cycle (Srinivas Pandruvada).
 
  - Fix kernel build with CONFIG_UBSAN set and CONFIG_CPU_IDLE
    unset (Catalin Marinas).
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Merge tag 'pm-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "Stable-candidate fixes for the intel_pstate driver and the cpuidle
  core.

  Specifics:

   - Fix two intel_pstate initialization issues, one of which was
     introduced during the 4.4 cycle (Srinivas Pandruvada)

   - Fix kernel build with CONFIG_UBSAN set and CONFIG_CPU_IDLE unset
     (Catalin Marinas)"

* tag 'pm-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo
  cpufreq: intel_pstate: Fix code ordering in intel_pstate_set_policy()
  cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
2016-06-10 08:09:12 -07:00
Rafael J. Wysocki
3681196ae5 Merge branches 'pm-cpufreq-fixes' and 'pm-cpuidle'
* pm-cpufreq-fixes:
  cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo
  cpufreq: intel_pstate: Fix code ordering in intel_pstate_set_policy()

* pm-cpuidle:
  cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
2016-06-09 23:49:16 +02:00
Zhouyi Zhou
ba62bafe94 kernel/relay.c: fix potential memory leak
When relay_open_buf() fails in relay_open(), code will goto free_bufs,
but chan is nowhere freed.

Link: http://lkml.kernel.org/r/1464777927-19675-1-git-send-email-yizhouzhou@ict.ac.cn
Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-09 14:23:11 -07:00
Mel Gorman
077fa7aed1 futex: Calculate the futex key based on a tail page for file-based futexes
Mike Galbraith reported that the LTP test case futex_wake04 was broken
by commit 65d8fc777f ("futex: Remove requirement for lock_page()
in get_futex_key()").

This test case uses futexes backed by hugetlbfs pages and so there is an
associated inode with a futex stored on such pages. The problem is that
the key is being calculated based on the head page index of the hugetlbfs
page and not the tail page.

Prior to the optimisation, the page lock was used to stabilise mappings and
pin the inode is file-backed which is overkill. If the page was a compound
page, the head page was automatically looked up as part of the page lock
operation but the tail page index was used to calculate the futex key.

After the optimisation, the compound head is looked up early and the page
lock is only relied upon to identify truncated pages, special pages or a
shmem page moving to swapcache. The head page is looked up because without
the page lock, special care has to be taken to pin the inode correctly.
However, the tail page is still required to calculate the futex key so
this patch records the tail page.

On vanilla 4.6, the output of the test case is;

futex_wake04    0  TINFO  :  Hugepagesize 2097152
futex_wake04    1  TFAIL  :  futex_wake04.c:126: Bug: wait_thread2 did not wake after 30 secs.

With the patch applied

futex_wake04    0  TINFO  :  Hugepagesize 2097152
futex_wake04    1  TPASS  :  Hi hydra, thread2 awake!

Fixes: 65d8fc777f "futex: Remove requirement for lock_page() in get_futex_key()"
Reported-and-tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160608132522.GM2469@suse.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-06-08 19:23:54 +02:00
Josh Poimboeuf
4698f88c06 sched/debug: Fix 'schedstats=enable' cmdline option
The 'schedstats=enable' option doesn't work, and also produces the
following warning during boot:

  WARNING: CPU: 0 PID: 0 at /home/jpoimboe/git/linux/kernel/jump_label.c:61 static_key_slow_inc+0x8c/0xa0
  static_key_slow_inc used before call to jump_label_init
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 4.7.0-rc1+ #25
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
   0000000000000086 3ae3475a4bea95d4 ffffffff81e03da8 ffffffff8143fc83
   ffffffff81e03df8 0000000000000000 ffffffff81e03de8 ffffffff810b1ffb
   0000003d00000096 ffffffff823514d0 ffff88007ff197c8 0000000000000000
  Call Trace:
   [<ffffffff8143fc83>] dump_stack+0x85/0xc2
   [<ffffffff810b1ffb>] __warn+0xcb/0xf0
   [<ffffffff810b207f>] warn_slowpath_fmt+0x5f/0x80
   [<ffffffff811e9c0c>] static_key_slow_inc+0x8c/0xa0
   [<ffffffff810e07c6>] static_key_enable+0x16/0x40
   [<ffffffff8216d633>] setup_schedstats+0x29/0x94
   [<ffffffff82148a05>] unknown_bootoption+0x89/0x191
   [<ffffffff810d8617>] parse_args+0x297/0x4b0
   [<ffffffff82148d61>] start_kernel+0x1d8/0x4a9
   [<ffffffff8214897c>] ? set_init_arg+0x55/0x55
   [<ffffffff82148120>] ? early_idt_handler_array+0x120/0x120
   [<ffffffff821482db>] x86_64_start_reservations+0x2f/0x31
   [<ffffffff82148427>] x86_64_start_kernel+0x14a/0x16d

The problem is that it tries to update the 'sched_schedstats' static key
before jump labels have been initialized.

Changing jump_label_init() to be called earlier before
parse_early_param() wouldn't fix it: it would still fail trying to
poke_text() because mm isn't yet initialized.

Instead, just create a temporary '__sched_schedstats' variable which can
be copied to the static key later during sched_init() after jump labels
have been initialized.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/453775fe3433bed65731a583e228ccea806d18cd.1465322027.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08 14:33:05 +02:00
Josh Poimboeuf
9c57259117 sched/debug: Fix /proc/sched_debug regression
Commit:

  cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")

... introduced a bug when CONFIG_SCHEDSTATS is enabled and the
runtime tunable is disabled (which is the default).

The wait-time, sum-exec, and sum-sleep fields are missing from the
/proc/sched_debug file in the runnable_tasks section.

Fix it with a new schedstat_val() macro which returns the field value
when schedstats is enabled and zero otherwise.  The macro works with
both SCHEDSTATS and !SCHEDSTATS.  I put the macro in stats.h since it
might end up being useful in other places.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08 14:31:58 +02:00
Alexander Shishkin
62a92c8f55 perf/core: Remove a redundant check
There is no way to end up in _free_event() with event::pmu being NULL.
The latter is initialized in event allocation path and remains set
forever. In case of allocation failure, the error path doesn't use
_free_event().

Having the check, however, suggests that it is possible to have a
event::pmu==NULL situation in _free_event() and confuses the robots.

This patch gets rid of the check.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1465303455-26032-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08 14:30:01 +02:00
Peter Zijlstra
2c61002271 locking/qspinlock: Fix spin_unlock_wait() some more
While this prior commit:

  54cf809b95 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")

... fixes spin_is_locked() and spin_unlock_wait() for the usage
in ipc/sem and netfilter, it does not in fact work right for the
usage in task_work and futex.

So while the 2 locks crossed problem:

	spin_lock(A)		spin_lock(B)
	if (!spin_is_locked(B)) spin_unlock_wait(A)
	  foo()			foo();

... works with the smp_mb() injected by both spin_is_locked() and
spin_unlock_wait(), this is not sufficient for:

	flag = 1;
	smp_mb();		spin_lock()
	spin_unlock_wait()	if (!flag)
				  // add to lockless list
	// iterate lockless list

... because in this scenario, the store from spin_lock() can be delayed
past the load of flag, uncrossing the variables and loosing the
guarantee.

This patch reworks spin_is_locked() and spin_unlock_wait() to work in
both cases by exploiting the observation that while the lock byte
store can be delayed, the contender must have registered itself
visibly in other state contained in the word.

It also allows for architectures to override both functions, as PPC
and ARM64 have an additional issue for which we currently have no
generic solution.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <waiman.long@hpe.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org # v4.2 and later
Fixes: 54cf809b95 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08 14:29:08 +02:00
Daniel Borkmann
5b6c1b4d46 bpf, trace: use READ_ONCE for retrieving file ptr
In bpf_perf_event_read() and bpf_perf_event_output(), we must use
READ_ONCE() for fetching the struct file pointer, which could get
updated concurrently, so we must prevent the compiler from potential
refetching.

We already do this with tail calls for fetching the related bpf_prog,
but not so on stored perf events. Semantics for both are the same
with regards to updates.

Fixes: a43eec3042 ("bpf: introduce bpf_perf_event_output() helper")
Fixes: 35578d7984 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-07 14:48:03 -07:00
Linus Torvalds
8c52b6dcdd 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 few simple fixes for fallout from the recent gic-v3 changes
 - a workaround for a Cavium thunderX erratum
 - a bugfix for the pic32 irqchip to make external interrupts work proper
 - a missing return value in the generic IPI management code

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/irq-pic32-evic: Fix bug with external interrupts.
  irqchip/gicv3-its: numa: Enable workaround for Cavium thunderx erratum 23144
  irqchip/gic-v3: Fix quiescence check in gic_enable_redist
  irqchip/gic-v3: Fix copy+paste mistakes in defines
  irqchip/gic-v3: Fix ICC_SGI1R_EL1.INTID decoding mask
  genirq: Fix missing return value in irq_destroy_ipi()
2016-06-03 16:12:35 -07:00
Thomas Gleixner
2eec3707a3 irqchip updates for 4.7-rc1:
- A number of embarassing buglets (GICv3, PIC32)
 - A more substential errata workaround for Cavium's GICv3 ITS
   (kept for post-rc1 due to its dependency on NUMA)
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Merge tag 'irqchip-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Merge irqchip updates from Marc Zyngier:

- A number of embarassing buglets (GICv3, PIC32)
- A more substential errata workaround for Cavium's GICv3 ITS
  (kept for post-rc1 due to its dependency on NUMA)
2016-06-03 15:05:51 +02:00
Chris Wilson
0422e83d84 locking/ww_mutex: Report recursive ww_mutex locking early
Recursive locking for ww_mutexes was originally conceived as an
exception. However, it is heavily used by the DRM atomic modesetting
code. Currently, the recursive deadlock is checked after we have queued
up for a busy-spin and as we never release the lock, we spin until
kicked, whereupon the deadlock is discovered and reported.

A simple solution for the now common problem is to move the recursive
deadlock discovery to the first action when taking the ww_mutex.

Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1464293297-19777-1-git-send-email-chris@chris-wilson.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-03 08:37:26 +02:00
Viresh Kumar
bf2be2de84 cpufreq: governor: Create cpufreq_policy_apply_limits()
Create a new helper to avoid code duplication across governors.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-02 23:24:39 +02:00
Rafael J. Wysocki
e788892ba3 cpufreq: governor: Get rid of governor events
The design of the cpufreq governor API is not very straightforward,
as struct cpufreq_governor provides only one callback to be invoked
from different code paths for different purposes.  The purpose it is
invoked for is determined by its second "event" argument, causing it
to act as a "callback multiplexer" of sorts.

Unfortunately, that leads to extra complexity in governors, some of
which implement the ->governor() callback as a switch statement
that simply checks the event argument and invokes a separate function
to handle that specific event.

That extra complexity can be eliminated by replacing the all-purpose
->governor() callback with a family of callbacks to carry out specific
governor operations: initialization and exit, start and stop and policy
limits updates.  That also turns out to reduce the code size too, so
do it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2016-06-02 23:24:15 +02:00
Catalin Marinas
9bd616e3db cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
The cpuidle_devices per-CPU variable is only defined when CPU_IDLE is
enabled. Commit c8cc7d4de7 ("sched/idle: Reorganize the idle loop")
removed the #ifdef CONFIG_CPU_IDLE around cpuidle_idle_call() with the
compiler optimising away __this_cpu_read(cpuidle_devices). However, with
CONFIG_UBSAN && !CONFIG_CPU_IDLE, this optimisation no longer happens
and the kernel fails to link since cpuidle_devices is not defined.

This patch introduces an accessor function for the current CPU cpuidle
device (returning NULL when !CONFIG_CPU_IDLE) and uses it in
cpuidle_idle_call().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: 4.5+ <stable@vger.kernel.org> # 4.5+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-06-02 23:05:27 +02:00
Linus Torvalds
6b15d6650c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Pull networking fixes from David Miller:

 1) Fix negative error code usage in ATM layer, from Stefan Hajnoczi.

 2) If CONFIG_SYSCTL is disabled, the default TTL is not initialized
    properly.  From Ezequiel Garcia.

 3) Missing spinlock init in mvneta driver, from Gregory CLEMENT.

 4) Missing unlocks in hwmb error paths, also from Gregory CLEMENT.

 5) Fix deadlock on team->lock when propagating features, from Ivan
    Vecera.

 6) Work around buffer offset hw bug in alx chips, from Feng Tang.

 7) Fix double listing of SCTP entries in sctp_diag dumps, from Xin
    Long.

 8) Various statistics bug fixes in mlx4 from Eric Dumazet.

 9) Fix some randconfig build errors wrt fou ipv6 from Arnd Bergmann.

10) All of l2tp was namespace aware, but the ipv6 support code was not
    doing so.  From Shmulik Ladkani.

11) Handle on-stack hrtimers properly in pktgen, from Guenter Roeck.

12) Propagate MAC changes properly through VLAN devices, from Mike
    Manning.

13) Fix memory leak in bnx2x_init_one(), from Vitaly Kuznetsov.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (62 commits)
  sfc: Track RPS flow IDs per channel instead of per function
  usbnet: smsc95xx: fix link detection for disabled autonegotiation
  virtio_net: fix virtnet_open and virtnet_probe competing for try_fill_recv
  bnx2x: avoid leaking memory on bnx2x_init_one() failures
  fou: fix IPv6 Kconfig options
  openvswitch: update checksum in {push,pop}_mpls
  sctp: sctp_diag should dump sctp socket type
  net: fec: update dirty_tx even if no skb
  vlan: Propagate MAC address to VLANs
  atm: iphase: off by one in rx_pkt()
  atm: firestream: add more reserved strings
  vxlan: Accept user specified MTU value when create new vxlan link
  net: pktgen: Call destroy_hrtimer_on_stack()
  timer: Export destroy_hrtimer_on_stack()
  net: l2tp: Make l2tp_ip6 namespace aware
  Documentation: ip-sysctl.txt: clarify secure_redirects
  sfc: use flow dissector helpers for aRFS
  ieee802154: fix logic error in ieee802154_llsec_parse_dev_addr
  net: nps_enet: Disable interrupts before napi reschedule
  net/lapb: tuse %*ph to dump buffers
  ...
2016-05-31 22:28:28 -07:00
Guenter Roeck
c08376ac97 timer: Export destroy_hrtimer_on_stack()
hrtimer_init_on_stack() needs a matching call to
destroy_hrtimer_on_stack(), so both need to be exported.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-31 11:44:08 -07:00
Linus Torvalds
d102a56edb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro:
 "Followups to the parallel lookup work:

   - update docs

   - restore killability of the places that used to take ->i_mutex
     killably now that we have down_write_killable() merged

   - Additionally, it turns out that I missed a prerequisite for
     security_d_instantiate() stuff - ->getxattr() wasn't the only thing
     that could be called before dentry is attached to inode; with smack
     we needed the same treatment applied to ->setxattr() as well"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch ->setxattr() to passing dentry and inode separately
  switch xattr_handler->set() to passing dentry and inode separately
  restore killability of old mutex_lock_killable(&inode->i_mutex) users
  add down_write_killable_nested()
  update D/f/directory-locking
2016-05-27 17:14:05 -07:00
Arnd Bergmann
287980e49f remove lots of IS_ERR_VALUE abuses
Most users of IS_ERR_VALUE() in the kernel are wrong, as they
pass an 'int' into a function that takes an 'unsigned long'
argument. This happens to work because the type is sign-extended
on 64-bit architectures before it gets converted into an
unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

Andrzej Hajda has already fixed a lot of the worst abusers that
were causing actual bugs, but it would be nice to prevent any
users that are not passing 'unsigned long' arguments.

This patch changes all users of IS_ERR_VALUE() that I could find
on 32-bit ARM randconfig builds and x86 allmodconfig. For the
moment, this doesn't change the definition of IS_ERR_VALUE()
because there are probably still architecture specific users
elsewhere.

Almost all the warnings I got are for files that are better off
using 'if (err)' or 'if (err < 0)'.
The only legitimate user I could find that we get a warning for
is the (32-bit only) freescale fman driver, so I did not remove
the IS_ERR_VALUE() there but changed the type to 'unsigned long'.
For 9pfs, I just worked around one user whose calling conventions
are so obscure that I did not dare change the behavior.

I was using this definition for testing:

 #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \
       unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO))

which ends up making all 16-bit or wider types work correctly with
the most plausible interpretation of what IS_ERR_VALUE() was supposed
to return according to its users, but also causes a compile-time
warning for any users that do not pass an 'unsigned long' argument.

I suggested this approach earlier this year, but back then we ended
up deciding to just fix the users that are obviously broken. After
the initial warning that caused me to get involved in the discussion
(fs/gfs2/dir.c) showed up again in the mainline kernel, Linus
asked me to send the whole thing again.

[ Updated the 9p parts as per Al Viro  - Linus ]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27 15:26:11 -07:00
Linus Torvalds
5b26fc8824 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild
Pull kbuild updates from Michal Marek:

 - new option CONFIG_TRIM_UNUSED_KSYMS which does a two-pass build and
   unexports symbols which are not used in the current config [Nicolas
   Pitre]

 - several kbuild rule cleanups [Masahiro Yamada]

 - warning option adjustments for gcov etc [Arnd Bergmann]

 - a few more small fixes

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (31 commits)
  kbuild: move -Wunused-const-variable to W=1 warning level
  kbuild: fix if_change and friends to consider argument order
  kbuild: fix adjust_autoksyms.sh for modules that need only one symbol
  kbuild: fix ksym_dep_filter when multiple EXPORT_SYMBOL() on the same line
  gcov: disable -Wmaybe-uninitialized warning
  gcov: disable tree-loop-im to reduce stack usage
  gcov: disable for COMPILE_TEST
  Kbuild: disable 'maybe-uninitialized' warning for CONFIG_PROFILE_ALL_BRANCHES
  Kbuild: change CC_OPTIMIZE_FOR_SIZE definition
  kbuild: forbid kernel directory to contain spaces and colons
  kbuild: adjust ksym_dep_filter for some cmd_* renames
  kbuild: Fix dependencies for final vmlinux link
  kbuild: better abstract vmlinux sequential prerequisites
  kbuild: fix call to adjust_autoksyms.sh when output directory specified
  kbuild: Get rid of KBUILD_STR
  kbuild: rename cmd_as_s_S to cmd_cpp_s_S
  kbuild: rename cmd_cc_i_c to cmd_cpp_i_c
  kbuild: drop redundant "PHONY += FORCE"
  kbuild: delete unnecessary "@:"
  kbuild: mark help target as PHONY
  ...
2016-05-26 22:01:22 -07:00
Michal Hocko
7ef949d77f mm: oom_reaper: remove some bloat
mmput_async is currently used only from the oom_reaper which is defined
only for CONFIG_MMU.  We can save work_struct in mm_struct for
!CONFIG_MMU.

[akpm@linux-foundation.org: fix typo, per Minchan]
Link: http://lkml.kernel.org/r/20160520061658.GB19172@dhcp22.suse.cz
Reported-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-26 15:35:44 -07:00
Al Viro
887bddfa90 add down_write_killable_nested()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-26 00:04:58 -04:00
Linus Torvalds
f89eae4ee7 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Two fixes: one for a lost wakeup, the other to fix the compiler
  optimizing out preempt operations on ARM64 (and possibly other non-x86
  architectures)"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix remote wakeups
  sched/preempt: Fix preempt_count manipulations
2016-05-25 17:11:43 -07:00