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  1. 22 8月, 2018 1 次提交
    • J
      workqueue: skip lockdep wq dependency in cancel_work_sync() · d6e89786
      由 Johannes Berg 提交于 
      In cancel_work_sync(), we can only have one of two cases, even
with an ordered workqueue:
 * the work isn't running, just cancelled before it started
 * the work is running, but then nothing else can be on the
   workqueue before it

Thus, we need to skip the lockdep workqueue dependency handling,
otherwise we get false positive reports from lockdep saying that
we have a potential deadlock when the workqueue also has other
work items with locking, e.g.

  work1_function() { mutex_lock(&mutex); ... }
  work2_function() { /* nothing */ }

  other_function() {
    queue_work(ordered_wq, &work1);
    queue_work(ordered_wq, &work2);
    mutex_lock(&mutex);
    cancel_work_sync(&work2);
  }

As described above, this isn't a problem, but lockdep will
currently flag it as if cancel_work_sync() was flush_work(),
which *is* a problem.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
      d6e89786
  3. 24 5月, 2018 1 次提交
    • M
      workqueue: move function definitions within CONFIG_SMP block · 66448bc2
      由 Mathieu Malaterre 提交于 
      In commit 7ee681b2 ("workqueue: Convert to state machine callbacks"),
three new function definitions were added: ‘workqueue_prepare_cpu’,
‘workqueue_online_cpu’ and ‘workqueue_offline_cpu’.

Move these function definitions within a CONFIG_SMP block since they are
not used outside of it. This will match function declarations in header
<include/linux/workqueue.h>, and silence the following gcc warning (W=1):

  kernel/workqueue.c:4743:5: warning: no previous prototype for ‘workqueue_prepare_cpu’ [-Wmissing-prototypes]
  kernel/workqueue.c:4756:5: warning: no previous prototype for ‘workqueue_online_cpu’ [-Wmissing-prototypes]
  kernel/workqueue.c:4783:5: warning: no previous prototype for ‘workqueue_offline_cpu’ [-Wmissing-prototypes]
Signed-off-by: NMathieu Malaterre <malat@debian.org>
Signed-off-by: NTejun Heo <tj@kernel.org>
      66448bc2
  5. 21 5月, 2018 1 次提交
  7. 18 5月, 2018 4 次提交
    • T
      workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status} · 6b59808b
      由 Tejun Heo 提交于 
      There can be a lot of workqueue workers and they all show up with the
cryptic kworker/* names making it difficult to understand which is
doing what and how they came to be.

  # ps -ef | grep kworker
  root           4       2  0 Feb25 ?        00:00:00 [kworker/0:0H]
  root           6       2  0 Feb25 ?        00:00:00 [kworker/u112:0]
  root          19       2  0 Feb25 ?        00:00:00 [kworker/1:0H]
  root          25       2  0 Feb25 ?        00:00:00 [kworker/2:0H]
  root          31       2  0 Feb25 ?        00:00:00 [kworker/3:0H]
  ...

This patch makes workqueue workers report the latest workqueue it was
executing for through /proc/PID/{comm,stat,status}.  The extra
information is appended to the kthread name with intervening '+' if
currently executing, otherwise '-'.

  # cat /proc/25/comm
  kworker/2:0-events_power_efficient
  # cat /proc/25/stat
  25 (kworker/2:0-events_power_efficient) I 2 0 0 0 -1 69238880 0 0...
  # grep Name /proc/25/status
  Name:   kworker/2:0-events_power_efficient

Unfortunately, ps(1) truncates comm to 15 characters,

  # ps 25
    PID TTY      STAT   TIME COMMAND
     25 ?        I      0:00 [kworker/2:0-eve]

making it a lot less useful; however, this should be an easy fix from
ps(1) side.
Signed-off-by: NTejun Heo <tj@kernel.org>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Craig Small <csmall@enc.com.au>
      6b59808b
    • T
      workqueue: Set worker->desc to workqueue name by default · 8bf89593
      由 Tejun Heo 提交于 
      Work functions can use set_worker_desc() to improve the visibility of
what the worker task is doing.  Currently, the desc field is unset at
the beginning of each execution and there is a separate field to track
the field is set during the current execution.

Instead of leaving empty till desc is set, worker->desc can be used to
remember the last workqueue the worker worked on by default and users
that use set_worker_desc() can override it to something more
informative as necessary.

This simplifies desc handling and helps tracking the last workqueue
that the worker exected on to improve visibility.
Signed-off-by: NTejun Heo <tj@kernel.org>
      8bf89593
    • T
      workqueue: Make worker_attach/detach_pool() update worker->pool · a2d812a2
      由 Tejun Heo 提交于 
      For historical reasons, the worker attach/detach functions don't
currently manage worker->pool and the callers are manually and
inconsistently updating it.

This patch moves worker->pool updates into the worker attach/detach
functions.  This makes worker->pool consistent and clearly defines how
worker->pool updates are synchronized.

This will help later workqueue visibility improvements by allowing
safe access to workqueue information from worker->task.
Signed-off-by: NTejun Heo <tj@kernel.org>
      a2d812a2
    • T
      workqueue: Replace pool->attach_mutex with global wq_pool_attach_mutex · 1258fae7
      由 Tejun Heo 提交于 
      To improve workqueue visibility, we want to be able to access
workqueue information from worker tasks.  The per-pool attach mutex
makes that difficult because there's no way of stabilizing task ->
worker pool association without knowing the pool first.

Worker attach/detach is a slow path and there's no need for different
pools to be able to perform them concurrently.  This patch replaces
the per-pool attach_mutex with global wq_pool_attach_mutex to prepare
for visibility improvement changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
      1258fae7
  9. 12 5月, 2018 2 次提交
  11. 11 5月, 2018 2 次提交
  13. 09 5月, 2018 2 次提交
  15. 05 5月, 2018 3 次提交
  17. 04 5月, 2018 3 次提交
  19. 03 5月, 2018 9 次提交
    • Z
      tracing: Fix the file mode of stack tracer · 0c5a9acc
      由 Zhengyuan Liu 提交于 
      It looks weird that the stack_trace_filter file can be written by root
but shows that it does not have write permission by ll command.

Link: http://lkml.kernel.org/r/1518054113-28096-1-git-send-email-liuzhengyuan@kylinos.cnSigned-off-by: NZhengyuan Liu <liuzhengyuan@kylinos.cn>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      0c5a9acc
    • C
      ftrace: Have set_graph_* files have normal file modes · 1ce0500d
      由 Chen LinX 提交于 
      The set_graph_function and set_graph_notrace file mode should be 0644
instead of 0444 as they are writeable. Note, the mode appears to be ignored
regardless, but they should at least look sane.

Link: http://lkml.kernel.org/r/1409725869-4501-1-git-send-email-linx.z.chen@intel.comAcked-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NChen LinX <linx.z.chen@intel.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      1ce0500d
    • P
      kthread, sched/wait: Fix kthread_parkme() completion issue · 85f1abe0
      由 Peter Zijlstra 提交于 
      Even with the wait-loop fixed, there is a further issue with
kthread_parkme(). Upon hotplug, when we do takedown_cpu(),
smpboot_park_threads() can return before all those threads are in fact
blocked, due to the placement of the complete() in __kthread_parkme().

When that happens, sched_cpu_dying() -> migrate_tasks() can end up
migrating such a still runnable task onto another CPU.

Normally the task will have hit schedule() and gone to sleep by the
time we do kthread_unpark(), which will then do __kthread_bind() to
re-bind the task to the correct CPU.

However, when we loose the initial TASK_PARKED store to the concurrent
wakeup issue described previously, do the complete(), get migrated, it
is possible to either:

 - observe kthread_unpark()'s clearing of SHOULD_PARK and terminate
   the park and set TASK_RUNNING, or

 - __kthread_bind()'s wait_task_inactive() to observe the competing
   TASK_RUNNING store.

Either way the WARN() in __kthread_bind() will trigger and fail to
correctly set the CPU affinity.

Fix this by only issuing the complete() when the kthread has scheduled
out. This does away with all the icky 'still running' nonsense.

The alternative is to promote TASK_PARKED to a special state, this
guarantees wait_task_inactive() cannot observe a 'stale' TASK_RUNNING
and we'll end up doing the right thing, but this preserves the whole
icky business of potentially migating the still runnable thing.
Reported-by: NGaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      85f1abe0
    • P
      kthread, sched/wait: Fix kthread_parkme() wait-loop · 741a76b3
      由 Peter Zijlstra 提交于 
      Gaurav reported a problem with __kthread_parkme() where a concurrent
try_to_wake_up() could result in competing stores to ->state which,
when the TASK_PARKED store got lost bad things would happen.

The comment near set_current_state() actually mentions this competing
store, but only mentions the case against TASK_RUNNING. This same
store, with different timing, can happen against a subsequent !RUNNING
store.

This normally is not a problem, because as per that same comment, the
!RUNNING state store is inside a condition based wait-loop:

  for (;;) {
    set_current_state(TASK_UNINTERRUPTIBLE);
    if (!need_sleep)
      break;
    schedule();
  }
  __set_current_state(TASK_RUNNING);

If we loose the (first) TASK_UNINTERRUPTIBLE store to a previous
(concurrent) wakeup, the schedule() will NO-OP and we'll go around the
loop once more.

The problem here is that the TASK_PARKED store is not inside the
KTHREAD_SHOULD_PARK condition wait-loop.

There is a genuine issue with sleeps that do not have a condition;
this is addressed in a subsequent patch.
Reported-by: NGaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      741a76b3
    • V
      sched/fair: Fix the update of blocked load when newly idle · 457be908
      由 Vincent Guittot 提交于 
      With commit:

  31e77c93 ("sched/fair: Update blocked load when newly idle")

... we release the rq->lock when updating blocked load of idle CPUs.

This opens a time window during which another CPU can add a task to this
CPU's cfs_rq.

The check for newly added task of idle_balance() is not in the common path.
Move the out label to include this check.
Reported-by: NHeiner Kallweit <hkallweit1@gmail.com>
Tested-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.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>
Fixes: 31e77c93 ("sched/fair: Update blocked load when newly idle")
Link: http://lkml.kernel.org/r/20180426103133.GA6953@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      457be908
    • P
      stop_machine, sched: Fix migrate_swap() vs. active_balance() deadlock · 0b26351b
      由 Peter Zijlstra 提交于 
      Matt reported the following deadlock:

CPU0					CPU1

schedule(.prev=migrate/0)		<fault>
  pick_next_task()			  ...
    idle_balance()			    migrate_swap()
      active_balance()			      stop_two_cpus()
						spin_lock(stopper0->lock)
						spin_lock(stopper1->lock)
						ttwu(migrate/0)
						  smp_cond_load_acquire() -- waits for schedule()
        stop_one_cpu(1)
	  spin_lock(stopper1->lock) -- waits for stopper lock

Fix this deadlock by taking the wakeups out from under stopper->lock.
This allows the active_balance() to queue the stop work and finish the
context switch, which in turn allows the wakeup from migrate_swap() to
observe the context and complete the wakeup.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reported-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMatt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180420095005.GH4064@hirez.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      0b26351b
    • J
      bpf: sockmap, fix error handling in redirect failures · abaeb096
      由 John Fastabend 提交于 
      When a redirect failure happens we release the buffers in-flight
without calling a sk_mem_uncharge(), the uncharge is called before
dropping the sock lock for the redirecte, however we missed updating
the ring start index. When no apply actions are in progress this
is OK because we uncharge the entire buffer before the redirect.
But, when we have apply logic running its possible that only a
portion of the buffer is being redirected. In this case we only
do memory accounting for the buffer slice being redirected and
expect to be able to loop over the BPF program again and/or if
a sock is closed uncharge the memory at sock destruct time.

With an invalid start index however the program logic looks at
the start pointer index, checks the length, and when seeing the
length is zero (from the initial release and failure to update
the pointer) aborts without uncharging/releasing the remaining
memory.

The fix for this is simply to update the start index. To avoid
fixing this error in two locations we do a small refactor and
remove one case where it is open-coded. Then fix it in the
single function.
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
      abaeb096
    • J
      bpf: sockmap, zero sg_size on error when buffer is released · fec51d40
      由 John Fastabend 提交于 
      When an error occurs during a redirect we have two cases that need
to be handled (i) we have a cork'ed buffer (ii) we have a normal
sendmsg buffer.

In the cork'ed buffer case we don't currently support recovering from
errors in a redirect action. So the buffer is released and the error
should _not_ be pushed back to the caller of sendmsg/sendpage. The
rationale here is the user will get an error that relates to old
data that may have been sent by some arbitrary thread on that sock.
Instead we simple consume the data and tell the user that the data
has been consumed. We may add proper error recovery in the future.
However, this patch fixes a bug where the bytes outstanding counter
sg_size was not zeroed. This could result in a case where if the user
has both a cork'ed action and apply action in progress we may
incorrectly call into the BPF program when the user expected an
old verdict to be applied via the apply action. I don't have a use
case where using apply and cork at the same time is valid but we
never explicitly reject it because it should work fine. This patch
ensures the sg_size is zeroed so we don't have this case.

In the normal sendmsg buffer case (no cork data) we also do not
zero sg_size. Again this can confuse the apply logic when the logic
calls into the BPF program when the BPF programmer expected the old
verdict to remain. So ensure we set sg_size to zero here as well. And
additionally to keep the psock state in-sync with the sk_msg_buff
release all the memory as well. Previously we did this before
returning to the user but this left a gap where psock and sk_msg_buff
states were out of sync which seems fragile. No additional overhead
is taken here except for a call to check the length and realize its
already been freed. This is in the error path as well so in my
opinion lets have robust code over optimized error paths.
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
      fec51d40
    • J
      bpf: sockmap, fix scatterlist update on error path in send with apply · 3cc9a472
      由 John Fastabend 提交于 
      When the call to do_tcp_sendpage() fails to send the complete block
requested we either retry if only a partial send was completed or
abort if we receive a error less than or equal to zero. Before
returning though we must update the scatterlist length/offset to
account for any partial send completed.

Before this patch we did this at the end of the retry loop, but
this was buggy when used while applying a verdict to fewer bytes
than in the scatterlist. When the scatterlist length was being set
we forgot to account for the apply logic reducing the size variable.
So the result was we chopped off some bytes in the scatterlist without
doing proper cleanup on them. This results in a WARNING when the
sock is tore down because the bytes have previously been charged to
the socket but are never uncharged.

The simple fix is to simply do the accounting inside the retry loop
subtracting from the absolute scatterlist values rather than trying
to accumulate the totals and subtract at the end.
Reported-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
      3cc9a472
  21. 02 5月, 2018 4 次提交
  23. 01 5月, 2018 1 次提交
  25. 27 4月, 2018 5 次提交
  27. 26 4月, 2018 2 次提交
    • T
      Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME · a3ed0e43
      由 Thomas Gleixner 提交于 
      Revert commits

92af4dcb ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a404 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e ("timekeeping: Remove boot time specific code")
f2d6fdbf ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449a ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320 ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
  of suspending (Genki Sky).  [Verified that that's because systemd uses
  CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
  systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
  (Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
  after resume 50% of the time (Pavel).  [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
  system resume (Pavel).

* Full system hang during resume (me).  [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.
Reported-by: NRafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
      a3ed0e43
    • T
      tick/sched: Do not mess with an enqueued hrtimer · 1f71addd
      由 Thomas Gleixner 提交于 
      Kaike reported that in tests rdma hrtimers occasionaly stopped working. He
did great debugging, which provided enough context to decode the problem.

CPU 3			     	      	     CPU 2

idle
start sched_timer expires = 712171000000
 queue->next = sched_timer
					    start rdmavt timer. expires = 712172915662
					    lock(baseof(CPU3))
tick_nohz_stop_tick()
tick = 716767000000			    timerqueue_add(tmr)

hrtimer_set_expires(sched_timer, tick);
  sched_timer->expires = 716767000000  <---- FAIL
					     if (tmr->expires < queue->next->expires)
hrtimer_start(sched_timer)		          queue->next = tmr;
lock(baseof(CPU3))
					     unlock(baseof(CPU3))
timerqueue_remove()
timerqueue_add()

ts->sched_timer is queued and queue->next is pointing to it, but then
ts->sched_timer.expires is modified.

This not only corrupts the ordering of the timerqueue RB tree, it also
makes CPU2 see the new expiry time of timerqueue->next->expires when
checking whether timerqueue->next needs to be updated. So CPU2 sees that
the rdma timer is earlier than timerqueue->next and sets the rdma timer as
new next.

Depending on whether it had also seen the new time at RB tree enqueue, it
might have queued the rdma timer at the wrong place and then after removing
the sched_timer the RB tree is completely hosed.

The problem was introduced with a commit which tried to solve inconsistency
between the hrtimer in the tick_sched data and the underlying hardware
clockevent. It split out hrtimer_set_expires() to store the new tick time
in both the NOHZ and the NOHZ + HIGHRES case, but missed the fact that in
the NOHZ + HIGHRES case the hrtimer might still be queued.

Use hrtimer_start(timer, tick...) for the NOHZ + HIGHRES case which sets
timer->expires after canceling the timer and move the hrtimer_set_expires()
invocation into the NOHZ only code path which is not affected as it merily
uses the hrtimer as next event storage so code pathes can be shared with
the NOHZ + HIGHRES case.

Fixes: d4af6d93 ("nohz: Fix spurious warning when hrtimer and clockevent get out of sync")
Reported-by: N"Wan Kaike" <kaike.wan@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NFrederic Weisbecker <frederic@kernel.org>
Cc: "Marciniszyn Mike" <mike.marciniszyn@intel.com>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-rdma@vger.kernel.org
Cc: "Dalessandro Dennis" <dennis.dalessandro@intel.com>
Cc: "Fleck John" <john.fleck@intel.com>
Cc: stable@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "Weiny Ira" <ira.weiny@intel.com>
Cc: "linux-rdma@vger.kernel.org"
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1804241637390.1679@nanos.tec.linutronix.de
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1804242119210.1597@nanos.tec.linutronix.de
      1f71addd