Move the p->nr_cpus_allowed check into kernel/sched/core.c: select_task_rq().
This change will make fair.c, rt.c, and deadline.c all start with the
same logic.
Suggested-and-Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: "pang.xunlei" <pang.xunlei@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1415150077-59053-1-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

As discussed in [1], accounting IO is meant for blkio only. Document that
so driver authors won't use them for device io.

 [1] http://thread.gmane.org/gmane.linux.drivers.i2c/20470Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1415098901-2768-1-git-send-email-wsa@the-dreams.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Remove question mark:

 s/New utsname group?/New utsname namespace

Unified style for IPC:

 s/New ipcs/New ipc namespace
Signed-off-by: NChen Hanxiao <chenhanxiao@cn.fujitsu.com>
Acked-by: NSerge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/1415091082-15093-1-git-send-email-chenhanxiao@cn.fujitsu.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Nobody iterates over numa_group::task_list, this just confuses the readers.
Signed-off-by: NKirill Tkhai <ktkhai@parallels.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1415358456.28592.17.camel@tkhaiSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NIngo Molnar <mingo@kernel.org>

Commit d670ec13 "posix-cpu-timers: Cure SMP wobbles" fixes one glibc
test case in cost of breaking another one. After that commit, calling
clock_nanosleep(TIMER_ABSTIME, X) and then clock_gettime(&Y) can result
of Y time being smaller than X time.

Reproducer/tester can be found further below, it can be compiled and ran by:

	gcc -o tst-cpuclock2 tst-cpuclock2.c -pthread
	while ./tst-cpuclock2 ; do : ; done

This reproducer, when running on a buggy kernel, will complain
about "clock_gettime difference too small".

Issue happens because on start in thread_group_cputimer() we initialize
sum_exec_runtime of cputimer with threads runtime not yet accounted and
then add the threads runtime to running cputimer again on scheduler
tick, making it's sum_exec_runtime bigger than actual threads runtime.

KOSAKI Motohiro posted a fix for this problem, but that patch was never
applied: https://lkml.org/lkml/2013/5/26/191 .

This patch takes different approach to cure the problem. It calls
update_curr() when cputimer starts, that assure we will have updated
stats of running threads and on the next schedule tick we will account
only the runtime that elapsed from cputimer start. That also assure we
have consistent state between cpu times of individual threads and cpu
time of the process consisted by those threads.

Full reproducer (tst-cpuclock2.c):

	#define _GNU_SOURCE
	#include <unistd.h>
	#include <sys/syscall.h>
	#include <stdio.h>
	#include <time.h>
	#include <pthread.h>
	#include <stdint.h>
	#include <inttypes.h>

	/* Parameters for the Linux kernel ABI for CPU clocks.  */
	#define CPUCLOCK_SCHED          2
	#define MAKE_PROCESS_CPUCLOCK(pid, clock) \
		((~(clockid_t) (pid) << 3) | (clockid_t) (clock))

	static pthread_barrier_t barrier;

	/* Help advance the clock.  */
	static void *chew_cpu(void *arg)
	{
		pthread_barrier_wait(&barrier);
		while (1) ;

		return NULL;
	}

	/* Don't use the glibc wrapper.  */
	static int do_nanosleep(int flags, const struct timespec *req)
	{
		clockid_t clock_id = MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED);

		return syscall(SYS_clock_nanosleep, clock_id, flags, req, NULL);
	}

	static int64_t tsdiff(const struct timespec *before, const struct timespec *after)
	{
		int64_t before_i = before->tv_sec * 1000000000ULL + before->tv_nsec;
		int64_t after_i = after->tv_sec * 1000000000ULL + after->tv_nsec;

		return after_i - before_i;
	}

	int main(void)
	{
		int result = 0;
		pthread_t th;

		pthread_barrier_init(&barrier, NULL, 2);

		if (pthread_create(&th, NULL, chew_cpu, NULL) != 0) {
			perror("pthread_create");
			return 1;
		}

		pthread_barrier_wait(&barrier);

		/* The test.  */
		struct timespec before, after, sleeptimeabs;
		int64_t sleepdiff, diffabs;
		const struct timespec sleeptime = {.tv_sec = 0,.tv_nsec = 100000000 };

		/* The relative nanosleep.  Not sure why this is needed, but its presence
		   seems to make it easier to reproduce the problem.  */
		if (do_nanosleep(0, &sleeptime) != 0) {
			perror("clock_nanosleep");
			return 1;
		}

		/* Get the current time.  */
		if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &before) < 0) {
			perror("clock_gettime[2]");
			return 1;
		}

		/* Compute the absolute sleep time based on the current time.  */
		uint64_t nsec = before.tv_nsec + sleeptime.tv_nsec;
		sleeptimeabs.tv_sec = before.tv_sec + nsec / 1000000000;
		sleeptimeabs.tv_nsec = nsec % 1000000000;

		/* Sleep for the computed time.  */
		if (do_nanosleep(TIMER_ABSTIME, &sleeptimeabs) != 0) {
			perror("absolute clock_nanosleep");
			return 1;
		}

		/* Get the time after the sleep.  */
		if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &after) < 0) {
			perror("clock_gettime[3]");
			return 1;
		}

		/* The time after sleep should always be equal to or after the absolute sleep
		   time passed to clock_nanosleep.  */
		sleepdiff = tsdiff(&sleeptimeabs, &after);
		if (sleepdiff < 0) {
			printf("absolute clock_nanosleep woke too early: %" PRId64 "\n", sleepdiff);
			result = 1;

			printf("Before %llu.%09llu\n", before.tv_sec, before.tv_nsec);
			printf("After  %llu.%09llu\n", after.tv_sec, after.tv_nsec);
			printf("Sleep  %llu.%09llu\n", sleeptimeabs.tv_sec, sleeptimeabs.tv_nsec);
		}

		/* The difference between the timestamps taken before and after the
		   clock_nanosleep call should be equal to or more than the duration of the
		   sleep.  */
		diffabs = tsdiff(&before, &after);
		if (diffabs < sleeptime.tv_nsec) {
			printf("clock_gettime difference too small: %" PRId64 "\n", diffabs);
			result = 1;
		}

		pthread_cancel(th);

		return result;
	}
Signed-off-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141112155843.GA24803@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

While looking over the cpu-timer code I found that we appear to add
the delta for the calling task twice, through:

  cpu_timer_sample_group()
    thread_group_cputimer()
      thread_group_cputime()
        times->sum_exec_runtime += task_sched_runtime();

    *sample = cputime.sum_exec_runtime + task_delta_exec();

Which would make the sample run ahead, making the sleep short.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20141112113737.GI10476@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

Because the whole numa task selection stuff runs with preemption
enabled (its long and expensive) we can end up migrating and selecting
oneself as a swap target. This doesn't really work out well -- we end
up trying to acquire the same lock twice for the swap migrate -- so
avoid this.
Reported-and-Tested-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141110100328.GF29390@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

On latest mm + KASan patchset I've got this:

    ==================================================================
    BUG: AddressSanitizer: out of bounds access in sched_init_smp+0x3ba/0x62c at addr ffff88006d4bee6c
    =============================================================================
    BUG kmalloc-8 (Not tainted): kasan error
    -----------------------------------------------------------------------------

    Disabling lock debugging due to kernel taint
    INFO: Allocated in alloc_vfsmnt+0xb0/0x2c0 age=75 cpu=0 pid=0
     __slab_alloc+0x4b4/0x4f0
     __kmalloc_track_caller+0x15f/0x1e0
     kstrdup+0x44/0x90
     alloc_vfsmnt+0xb0/0x2c0
     vfs_kern_mount+0x35/0x190
     kern_mount_data+0x25/0x50
     pid_ns_prepare_proc+0x19/0x50
     alloc_pid+0x5e2/0x630
     copy_process.part.41+0xdf5/0x2aa0
     do_fork+0xf5/0x460
     kernel_thread+0x21/0x30
     rest_init+0x1e/0x90
     start_kernel+0x522/0x531
     x86_64_start_reservations+0x2a/0x2c
     x86_64_start_kernel+0x15b/0x16a
    INFO: Slab 0xffffea0001b52f80 objects=24 used=22 fp=0xffff88006d4befc0 flags=0x100000000004080
    INFO: Object 0xffff88006d4bed20 @offset=3360 fp=0xffff88006d4bee70

    Bytes b4 ffff88006d4bed10: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a  ........ZZZZZZZZ
    Object ffff88006d4bed20: 70 72 6f 63 00 6b 6b a5                          proc.kk.
    Redzone ffff88006d4bed28: cc cc cc cc cc cc cc cc                          ........
    Padding ffff88006d4bee68: 5a 5a 5a 5a 5a 5a 5a 5a                          ZZZZZZZZ
    CPU: 0 PID: 1 Comm: swapper/0 Tainted: G    B          3.18.0-rc3-mm1+ #108
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
     ffff88006d4be000 0000000000000000 ffff88006d4bed20 ffff88006c86fd18
     ffffffff81cd0a59 0000000000000058 ffff88006d404240 ffff88006c86fd48
     ffffffff811fa3a8 ffff88006d404240 ffffea0001b52f80 ffff88006d4bed20
    Call Trace:
    dump_stack (lib/dump_stack.c:52)
    print_trailer (mm/slub.c:645)
    object_err (mm/slub.c:652)
    ? sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063)
    kasan_report_error (mm/kasan/report.c:102 mm/kasan/report.c:178)
    ? kasan_poison_shadow (mm/kasan/kasan.c:48)
    ? kasan_unpoison_shadow (mm/kasan/kasan.c:54)
    ? kasan_poison_shadow (mm/kasan/kasan.c:48)
    ? kasan_kmalloc (mm/kasan/kasan.c:311)
    __asan_load4 (mm/kasan/kasan.c:371)
    ? sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063)
    sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063)
    kernel_init_freeable (init/main.c:869 init/main.c:997)
    ? finish_task_switch (kernel/sched/sched.h:1036 kernel/sched/core.c:2248)
    ? rest_init (init/main.c:924)
    kernel_init (init/main.c:929)
    ? rest_init (init/main.c:924)
    ret_from_fork (arch/x86/kernel/entry_64.S:348)
    ? rest_init (init/main.c:924)
    Read of size 4 by task swapper/0:
    Memory state around the buggy address:
     ffff88006d4beb80: fc fc fc fc fc fc fc fc fc fc 00 fc fc fc fc fc
     ffff88006d4bec00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88006d4bec80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88006d4bed00: fc fc fc fc 00 fc fc fc fc fc fc fc fc fc fc fc
     ffff88006d4bed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    >ffff88006d4bee00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc 04 fc
                                                              ^
     ffff88006d4bee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88006d4bef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
     ffff88006d4bef80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
     ffff88006d4bf000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
     ffff88006d4bf080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ==================================================================

Zero 'level' (e.g. on non-NUMA system) causing out of bounds
access in this line:

     sched_max_numa_distance = sched_domains_numa_distance[level - 1];

Fix this by exiting from sched_init_numa() earlier.
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Fixes: 9942f79b ("sched/numa: Export info needed for NUMA balancing on complex topologies")
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1415372020-1871-1-git-send-email-a.ryabinin@samsung.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch simplifies task_struct by removing the four numa_* pointers
in the same array and replacing them with the array pointer. By doing this,
on x86_64, the size of task_struct is reduced by 3 ulong pointers (24 bytes on
x86_64).

A new parameter is added to the task_faults_idx function so that it can return
an index to the correct offset, corresponding with the old precalculated
pointers.

All of the code in sched/ that depended on task_faults_idx and numa_* was
changed in order to match the new logic.
Signed-off-by: NIulia Manda <iulia.manda21@gmail.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: dave@stgolabs.net
Cc: riel@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141031001331.GA30662@winterfellSigned-off-by: NIngo Molnar <mingo@kernel.org>

There are both UP and SMP version of pull_dl_task(), so don't need
to check CONFIG_SMP in switched_from_dl();
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-6-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

In switched_from_dl() we have to issue a resched if we successfully
pulled some task from other cpus. This patch also aligns the behavior
with -rt.
Suggested-by: NJuri Lelli <juri.lelli@arm.com>
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-5-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch pushes task away if the dealine of the task is equal
to current during wake up. The same behavior as rt class.
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-4-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch add deadline rq status print.
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-3-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The yield semantic of deadline class is to reduce remaining runtime to
zero, and then update_curr_dl() will stop it. However, comsumed bandwidth
is reduced from the budget of yield task again even if it has already been
set to zero which leads to artificial overrun. This patch fix it by make
sure we don't steal some more time from the task that yielded in update_curr_dl().
Suggested-by: NJuri Lelli <juri.lelli@arm.com>
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-2-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch checks if current can be pushed/pulled somewhere else
in advance to make logic clear, the same behavior as dl class.

- If current can't be migrated, useless to reschedule, let's hope
  task can move out.
- If task is migratable, so let's not schedule it and see if it
  can be pushed or pulled somewhere else.
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414708776-124078-1-git-send-email-wanpeng.li@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

As per commit f10e00f4 ("sched/dl: Use dl_bw_of() under
rcu_read_lock_sched()"), dl_bw_of() has to be protected by
rcu_read_lock_sched().
Signed-off-by: NJuri Lelli <juri.lelli@arm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414497286-28824-1-git-send-email-juri.lelli@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Idle cpu is idler than non-idle cpu, so we needn't search for least_loaded_cpu
after we have found an idle cpu.
Signed-off-by: NYao Dongdong <yaodongdong@huawei.com>
Reviewed-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414469286-6023-1-git-send-email-yaodongdong@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently used hrtimer_try_to_cancel() is racy:

raw_spin_lock(&rq->lock)
...                            dl_task_timer                 raw_spin_lock(&rq->lock)
...                               raw_spin_lock(&rq->lock)   ...
   switched_from_dl()             ...                        ...
      hrtimer_try_to_cancel()     ...                        ...
   switched_to_fair()             ...                        ...
...                               ...                        ...
...                               ...                        ...
raw_spin_unlock(&rq->lock)        ...                        (asquired)
...                               ...                        ...
...                               ...                        ...
do_exit()                         ...                        ...
   schedule()                     ...                        ...
      raw_spin_lock(&rq->lock)    ...                        raw_spin_unlock(&rq->lock)
      ...                         ...                        ...
      raw_spin_unlock(&rq->lock)  ...                        raw_spin_lock(&rq->lock)
      ...                         ...                        (asquired)
      put_task_struct()           ...                        ...
          free_task_struct()      ...                        ...
      ...                         ...                        raw_spin_unlock(&rq->lock)
...                               (asquired)                 ...
...                               ...                        ...
...                               (use after free)           ...

So, let's implement 100% guaranteed way to cancel the timer and let's
be sure we are safe even in very unlikely situations.

rq unlocking does not limit the area of switched_from_dl() use, because
this has already been possible in pull_dl_task() below.

Let's consider the safety of of this unlocking. New code in the patch
is working when hrtimer_try_to_cancel() fails. This means the callback
is running. In this case hrtimer_cancel() is just waiting till the
callback is finished. Two

1) Since we are in switched_from_dl(), new class is not dl_sched_class and
new prio is not less MAX_DL_PRIO. So, the callback returns early; it's
right after !dl_task() check. After that hrtimer_cancel() returns back too.

The above is:

raw_spin_lock(rq->lock);                  ...
...                                       dl_task_timer()
...                                          raw_spin_lock(rq->lock);
   switched_from_dl()                        ...
       hrtimer_try_to_cancel()               ...
          raw_spin_unlock(rq->lock);         ...
          hrtimer_cancel()                   ...
          ...                                raw_spin_unlock(rq->lock);
          ...                                return HRTIMER_NORESTART;
          ...                             ...
          raw_spin_lock(rq->lock);        ...

2) But the below is also possible:
                                   dl_task_timer()
                                      raw_spin_lock(rq->lock);
                                      ...
                                      raw_spin_unlock(rq->lock);
raw_spin_lock(rq->lock);              ...
   switched_from_dl()                 ...
       hrtimer_try_to_cancel()        ...
       ...                            return HRTIMER_NORESTART;
       raw_spin_unlock(rq->lock);  ...
       hrtimer_cancel();           ...
       raw_spin_lock(rq->lock);    ...

In this case hrtimer_cancel() returns immediately. Very unlikely case,
just to mention.

Nobody can manipulate the task, because check_class_changed() is
always called with pi_lock locked. Nobody can force the task to
participate in (concurrent) priority inheritance schemes (the same reason).

All concurrent task operations require pi_lock, which is held by us.
No deadlocks with dl_task_timer() are possible, because it returns
right after !dl_task() check (it does nothing).

If we receive a new dl_task during the time of unlocked rq, we just
don't have to do pull_dl_task() in switched_from_dl() further.
Signed-off-by: NKirill Tkhai <ktkhai@parallels.com>
[ Added comments]
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NJuri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414420852.19914.186.camel@tkhaiSigned-off-by: NIngo Molnar <mingo@kernel.org>

In some cases this can trigger a true flood of output.
Requested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

rtnl_lock_unregistering*() take rtnl_lock() -- a mutex -- inside a
wait loop. The wait loop relies on current->state to function, but so
does mutex_lock(), nesting them makes for the inner to destroy the
outer state.

Fix this using the new wait_woken() bits.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <cwang@twopensource.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jerry Chu <hkchu@google.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Cc: sfeldma@cumulusnetworks.com <sfeldma@cumulusnetworks.com>
Cc: stephen hemminger <stephen@networkplumber.org>
Cc: Tom Gundersen <teg@jklm.no>
Cc: Tom Herbert <therbert@google.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Vlad Yasevich <vyasevic@redhat.com>
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20141029173110.GE15602@worktop.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

rfcomm_run() is a tad broken in that is has a nested wait loop. One
cannot rely on p->state for the outer wait because the inner wait will
overwrite it.

Fix this using the new wait_woken() facility.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Alexander Holler <holler@ahsoftware.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Joe Perches <joe@perches.com>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Libor Pechacek <lpechacek@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Vignesh Raman <Vignesh_Raman@mentor.com>
Cc: linux-bluetooth@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

The kauditd_thread wait loop is a bit iffy; it has a number of problems:

 - calls try_to_freeze() before schedule(); you typically want the
   thread to re-evaluate the sleep condition when unfreezing, also
   freeze_task() issues a wakeup.

 - it unconditionally does the {add,remove}_wait_queue(), even when the
   sleep condition is false.

Use wait_event_freezable() that does the right thing.
Reported-by: NMike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: oleg@redhat.com
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141002102251.GA6324@worktop.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>

There is no user.. make it go away.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux-pm@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Provide better implementations of wait_event_freezable() APIs.

The problem is with freezer_do_not_count(), it hides the thread from
the freezer, even though this thread might not actually freeze/sleep
at all.

Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-d86fz1jmso9wjxa8jfpinp8o@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

There is a race between kthread_stop() and the new wait_woken() that
can result in a lack of progress.

CPU 0                                    | CPU 1
                                         |
rfcomm_run()                             | kthread_stop()
  ...                                    |
  if (!test_bit(KTHREAD_SHOULD_STOP))    |
                                         |   set_bit(KTHREAD_SHOULD_STOP)
                                         |   wake_up_process()
    wait_woken()                         |   wait_for_completion()
      set_current_state(INTERRUPTIBLE)   |
      if (!WQ_FLAG_WOKEN)                |
        schedule_timeout()               |
                                         |

After which both tasks will wait.. forever.

Fix this by having wait_woken() check for kthread_should_stop() but
only for kthreads (obviously).
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

sched_move_task() is the only interface to change sched_task_group:
cpu_cgrp_subsys methods and autogroup_move_group() use it.

Everything is synchronized by task_rq_lock(), so cpu_cgroup_attach()
is ordered with other users of sched_move_task(). This means we do no
need RCU here: if we've dereferenced a tg here, the .attach method
hasn't been called for it yet.

Thus, we should pass "true" to task_css_check() to silence lockdep
warnings.

Fixes: eeb61e53 ("sched: Fix race between task_group and sched_task_group")
Reported-by: NOleg Nesterov <oleg@redhat.com>
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NKirill Tkhai <ktkhai@parallels.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414473874.8574.2.camel@tkhaiSigned-off-by: NIngo Molnar <mingo@kernel.org>

Pull pin-control fixes from Linus Walleij:
 "This kernel cycle has been calm for both pin control and GPIO so far
  but here are three pin control patches for you anyway, only really
  dealing with Baytrail:

   - Two fixes for the Baytrail driver affecting IRQs and output state
     in sysfs
   - Use the linux-gpio mailing list also for pinctrl patches"

* tag 'pinctrl-v3.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: baytrail: show output gpio state correctly on Intel Baytrail
  pinctrl: use linux-gpio mailing list
  pinctrl: baytrail: Clear DIRECT_IRQ bit

Pull CMA and DMA-mapping fixes from Marek Szyprowski:
 "This contains important fixes for recently introduced highmem support
  for default contiguous memory region used for dma-mapping subsystem"

* 'fixes-for-v3.18' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  mm, cma: make parameters order consistent in func declaration and definition
  mm: cma: Use %pa to print physical addresses
  mm: cma: Ensure that reservations never cross the low/high mem boundary
  mm: cma: Always consider a 0 base address reservation as dynamic
  mm: cma: Don't crash on allocation if CMA area can't be activated

Pull ceph fixes from Sage Weil:
 "There is a GFP flag fix from Mike Christie, an error code fix from
  Jan, and fixes for two unnecessary allocations (kmalloc and workqueue)
  from Ilya.  All are well tested.

  Ilya has one other fix on the way but it didn't get tested in time"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  libceph: eliminate unnecessary allocation in process_one_ticket()
  rbd: Fix error recovery in rbd_obj_read_sync()
  libceph: use memalloc flags for net IO
  rbd: use a single workqueue for all devices

Pull m68k update from Geert Uytterhoeven.

Just wiring up the bpf system call.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k: Wire up bpf

Pull ARM SoC fixes from Olof Johansson:
 "A surprisingly small batch of fixes for -rc3.  Suspiciously small, I'd
  say.

  Anyway, most of this are a few defconfig updates.  Some for omap to
  deal with kernel binary size (moving ipv6 to module, etc).  A larger
  one for socfpga that refreshes with some churn, but also turns on a
  few options that makes the newly-added board in my bootfarm usable for
  testing.

  OMAP3 will also now warn when booted with legacy (non-DT) boot
  protocols, hopefully encouraging those who still care about some of
  those platforms to submit DT support and report bugs where needed.
  Nothing stops working though, this is just to warn for future
  deprecation.

  Beyond this, very few actual bugfixes.  A PXA fix for DEBUG_LL boot
  hangs, a missing terminting entry in a dt_match array on RealView a
  MTD fix on OMAP with NAND"

[ Obviously missed rc3, will make rc4 instead ;) ]

* tag 'armsoc-for-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  MAINTAINERS: drop list entry for davinci
  ARM: OMAP2+: Warn about deprecated legacy booting mode
  ARM: omap2plus_defconfig: Fix errors with NAND BCH
  ARM: multi_v7_defconfig: fix support for APQ8084
  soc: versatile: Add terminating entry for realview_soc_of_match
  ARM: ixp4xx: remove compilation warnings in io.h
  MAINTAINERS: Add Soren as reviewer for Zynq
  ARM: omap2plus_defconfig: Fix bloat caused by having ipv6 built-in
  ARM: socfpga_defconfig: Update defconfig for SoCFPGA
  ARM: pxa: fix hang on startup with DEBUG_LL

Pull MTD fixes from Brian Norris:
 "Three main MTD fixes for 3.18:

   - A regression from 3.16 which was noticed in 3.17.  With the
     restructuring of the m25p80.c driver and the SPI NOR library
     framework, we omitted proper listing of the SPI device IDs.  This
     means m25p80.c wouldn't auto-load (modprobe) properly when built as
     a module.  For now, we duplicate the device IDs into both modules.

   - The OMAP / ELM modules were depending on an implicit link ordering.
     Use deferred probing so that the new link order (in 3.18-rc) can
     still allow for successful probing.

   - Fix suspend/resume support for LH28F640BF NOR flash"

* tag 'for-linus-20141102' of git://git.infradead.org/linux-mtd:
  mtd: cfi_cmdset_0001.c: fix resume for LH28F640BF chips
  mtd: omap: fix mtd devices not showing up
  mtd: m25p80,spi-nor: Fix module aliases for m25p80
  mtd: spi-nor: make spi_nor_scan() take a chip type name, not spi_device_id
  mtd: m25p80: get rid of spi_get_device_id

Pull SCSI fixes from James Bottomley:
 "This is a set of six patches consisting of:
   - two MAINTAINER updates
   - two scsi-mq fixs for the old parallel interface (not every request
     is tagged and we need to set the right flags to populate the SPI
     tag message)
   - a fix for a memory leak in scatterlist traversal caused by a
     preallocation update in 3.17
   - an ipv6 fix for cxgbi"

[ The scatterlist fix also came in separately through the block layer tree ]

* tag 'scsi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  MAINTAINERS: ufs - remove self
  MAINTAINERS: change hpsa and cciss maintainer
  libcxgbi : support ipv6 address host_param
  scsi: set REQ_QUEUE for the blk-mq case
  Revert "block: all blk-mq requests are tagged"
  lib/scatterlist: fix memory leak with scsi-mq

Pull drm fixes from Dave Airlie:
 "Nothing too astounding or major: radeon, i915, vmwgfx, armada and
  exynos.

  Biggest ones:
   - vmwgfx has one big locking regression fix
   - i915 has come displayport fixes
   - radeon has some stability and a memory alloc failure
   - armada and exynos have some vblank fixes"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (24 commits)
  drm/exynos: correct connector->dpms field before resuming
  drm/exynos: enable vblank after DPMS on
  drm/exynos: init kms poll at the end of initialization
  drm/exynos: propagate plane initialization errors
  drm/exynos: vidi: fix build warning
  drm/exynos: remove explicit encoder/connector de-initialization
  drm/exynos: init vblank with real number of crtcs
  drm/vmwgfx: Filter out modes those cannot be supported by the current VRAM size.
  drm/vmwgfx: Fix hash key computation
  drm/vmwgfx: fix lock breakage
  drm/i915/dp: only use training pattern 3 on platforms that support it
  drm/radeon: remove some buggy dead code
  drm/i915: Ignore VBT backlight check on Macbook 2, 1
  drm/radeon: remove invalid pci id
  drm/radeon: dpm fixes for asrock systems
  radeon: clean up coding style differences in radeon_get_bios()
  drm/radeon: Use drm_malloc_ab instead of kmalloc_array
  drm/radeon/dpm: disable ulv support on SI
  drm/i915: Fix GMBUSFREQ on vlv/chv
  drm/i915: Ignore long hpds on eDP ports
  ...

Merge tag 'fixes-against-v3.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes

Merge "omap fixes against v3.18-rc2" from Tony Lindgren:

Few fixes for omaps to enable NAND BCH so devices won't
produce errors when booted with omap2plus_defconfig, and
reduce bloat by making IPV6 a loadable module.

Also let's add a warning about legacy boot being deprecated
for omap3.

We now have things working with device tree, and only omap3 is
still booting in legacy mode. So hopefully this warning will
help move the remaining legacy mode users to boot with device
tree.

As the total reduction of code and static data is somewhere
around 20000 lines of code once we remove omap3 legacy mode
booting, we really do want to make omap3 to boot also in
device tree mode only over the next few merge cycles.

* tag 'fixes-against-v3.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap: (407 commits)
  ARM: OMAP2+: Warn about deprecated legacy booting mode
  ARM: omap2plus_defconfig: Fix errors with NAND BCH
  ARM: omap2plus_defconfig: Fix bloat caused by having ipv6 built-in
  + Linux 3.18-rc2
Signed-off-by: NOlof Johansson <olof@lixom.net>

Pull ARM fixes from Russell King:
 - add the new bpf syscall to ARM.
 - drop a redundant return statement in __iommu_alloc_remap()
 - fix a performance issue noticed by Thomas Petazzoni with
   kmap_atomic().
 - fix an issue with the L2 cache OF parsing code which caused it to
   incorrectly print warnings on each boot, and make the warning text
   more consistent with the rest of the code

* 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  ARM: 8180/1: mm: implement no-highmem fast path in kmap_atomic_pfn()
  ARM: 8183/1: l2c: Improve l2c310_of_parse() error message
  ARM: 8181/1: Drop extra return statement
  ARM: 8182/1: l2c: Make l2x0_cache_size_of_parse() return 'int'
  ARM: enable bpf syscall

Pull kvm fixes from Paolo Bonzini:
 "A small set of x86 fixes.  The most serious is an SRCU lockdep fix.

  A bit late - needed some time to test the SRCU fix, which only came in
  on Friday"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: vmx: defer load of APIC access page address during reset
  KVM: nVMX: Disable preemption while reading from shadow VMCS
  KVM: x86: Fix far-jump to non-canonical check
  KVM: emulator: fix execution close to the segment limit
  KVM: emulator: fix error code for __linearize

Merge branch 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos into drm-fixes

This pull-request includes some bug fixes and code cleanups.
Especially, this fixes the bind failure issue occurred when it tries
to re-bind Exynos drm driver after unbound, and the modetest failure
issue incurred by not having a pair to vblank on and off requests.

* 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos:
  drm/exynos: correct connector->dpms field before resuming
  drm/exynos: enable vblank after DPMS on
  drm/exynos: init kms poll at the end of initialization
  drm/exynos: propagate plane initialization errors
  drm/exynos: vidi: fix build warning
  drm/exynos: remove explicit encoder/connector de-initialization
  drm/exynos: init vblank with real number of crtcs