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Fix this lockdep warning:
[ 44.804600] =========================================================
[ 44.805746] [ INFO: possible irq lock inversion dependency detected ]
[ 44.805746] 3.14.0-rc2-test+ #14 Not tainted
[ 44.805746] ---------------------------------------------------------
[ 44.805746] bash/3674 just changed the state of lock:
[ 44.805746] (&dl_b->lock){+.....}, at: [<ffffffff8106ad15>] sched_rt_handler+0x132/0x248
[ 44.805746] but this lock was taken by another, HARDIRQ-safe lock in the past:
[ 44.805746] (&rq->lock){-.-.-.}
and interrupts could create inverse lock ordering between them.
[ 44.805746]
[ 44.805746] other info that might help us debug this:
[ 44.805746] Possible interrupt unsafe locking scenario:
[ 44.805746]
[ 44.805746] CPU0 CPU1
[ 44.805746] ---- ----
[ 44.805746] lock(&dl_b->lock);
[ 44.805746] local_irq_disable();
[ 44.805746] lock(&rq->lock);
[ 44.805746] lock(&dl_b->lock);
[ 44.805746] <Interrupt>
[ 44.805746] lock(&rq->lock);
by making dl_b->lock acquiring always IRQ safe.
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392107067-19907-3-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Don't compare sysctl_sched_rt_runtime against sysctl_sched_rt_period if
the former is equal to RUNTIME_INF, otherwise disabling -rt bandwidth
management (with CONFIG_RT_GROUP_SCHED=n) fails.
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392107067-19907-2-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
While debugging the crash with the bad nr_running accounting, I hit
another bug where, after running my sched deadline test, I was getting
failures to take a CPU offline. It was giving me a -EBUSY error.
Adding a bunch of trace_printk()s around, I found that the cpu
notifier that called sched_cpu_inactive() was returning a failure. The
overflow value was coming up negative?
Talking this over with Juri, the problem is that the total_bw update was
suppose to be made by dl_overflow() which, during my tests, seemed to
not be called. Adding more trace_printk()s, it wasn't that it wasn't
called, but it exited out right away with the check of new_bw being
equal to p->dl.dl_bw. The new_bw calculates the ratio between period and
runtime. The bug is that if you set a deadline, you do not need to set
a period if you plan on the period being equal to the deadline. That
is, if period is zero and deadline is not, then the system call should
set the period to be equal to the deadline. This is done elsewhere in
the code.
The fix is easy, check if period is set, and if it is not, then use the
deadline.
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140219135335.7e74abd4@gandalf.local.home
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Rostedt writes:
My test suite was locking up hard when enabling mmiotracer. This was due
to the mmiotracer placing all but one CPU offline. I found this out
when I was able to reproduce the bug with just my stress-cpu-hotplug
test. This bug baffled me because it would not always trigger, and
would only trigger on the first run after boot up. The
stress-cpu-hotplug test would crash hard the first run, or never crash
at all. But a new reboot may cause it to crash on the first run again.
I spent all week bisecting this, as I couldn't find a consistent
reproducer. I finally narrowed it down to the sched deadline patches,
and even more peculiar, to the commit that added the sched
deadline boot up self test to the latency tracer. Then it dawned on me
to what the bug was.
All it took was to run a task under sched deadline to screw up the CPU
hot plugging. This explained why it would lock up only on the first run
of the stress-cpu-hotplug test. The bug happened when the boot up self
test of the schedule latency tracer would test a deadline task. The
deadline task would corrupt something that would cause CPU hotplug to
fail. If it didn't corrupt it, the stress test would always work
(there's no other sched deadline tasks that would run to cause
problems). If it did corrupt on boot up, the first test would lockup
hard.
I proved this theory by running my deadline test program on another box,
and then run the stress-cpu-hotplug test, and it would now consistently
lock up. I could run stress-cpu-hotplug over and over with no problem,
but once I ran the deadline test, the next run of the
stress-cpu-hotplug would lock hard.
After adding lots of tracing to the code, I found the cause. The
function tracer showed that migrate_tasks() was stuck in an infinite
loop, where rq->nr_running never equaled 1 to break out of it. When I
added a trace_printk() to see what that number was, it was 335 and
never decrementing!
Looking at the deadline code I found:
static void __dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) {
dequeue_dl_entity(&p->dl);
dequeue_pushable_dl_task(rq, p);
}
static void dequeue_task_dl(struct rq *rq, struct task_struct *p, int flags) {
update_curr_dl(rq);
__dequeue_task_dl(rq, p, flags);
dec_nr_running(rq);
}
And this:
if (dl_runtime_exceeded(rq, dl_se)) {
__dequeue_task_dl(rq, curr, 0);
if (likely(start_dl_timer(dl_se, curr->dl.dl_boosted)))
dl_se->dl_throttled = 1;
else
enqueue_task_dl(rq, curr, ENQUEUE_REPLENISH);
if (!is_leftmost(curr, &rq->dl))
resched_task(curr);
}
Notice how we call __dequeue_task_dl() and in the else case we
call enqueue_task_dl()? Also notice that dequeue_task_dl() has
underscores where enqueue_task_dl() does not. The enqueue_task_dl()
calls inc_nr_running(rq), but __dequeue_task_dl() does not. This is
where we get nr_running out of sync.
[snip]
Another point where nr_running can get out of sync is when the dl_timer
fires:
dl_se->dl_throttled = 0;
if (p->on_rq) {
enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
if (task_has_dl_policy(rq->curr))
check_preempt_curr_dl(rq, p, 0);
else
resched_task(rq->curr);
This patch does two things:
- correctly accounts for throttled tasks (that are now considered
!running);
- fixes the bug, updating nr_running from {inc,dec}_dl_tasks(),
since we risk to update it twice in some situations (e.g., a
task is dequeued while it has exceeded its budget).
Cc: mingo@redhat.com
Cc: torvalds@linux-foundation.org
Cc: akpm@linux-foundation.org
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392884379-13744-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull cgroup fixes from Tejun Heo:
"Quite a few fixes this time.
Three locking fixes, all marked for -stable. A couple error path
fixes and some misc fixes. Hugh found a bug in memcg offlining
sequence and we thought we could fix that from cgroup core side but
that turned out to be insufficient and got reverted. A different fix
has been applied to -mm"
* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: update cgroup_enable_task_cg_lists() to grab siglock
Revert "cgroup: use an ordered workqueue for cgroup destruction"
cgroup: protect modifications to cgroup_idr with cgroup_mutex
cgroup: fix locking in cgroup_cfts_commit()
cgroup: fix error return from cgroup_create()
cgroup: fix error return value in cgroup_mount()
cgroup: use an ordered workqueue for cgroup destruction
nfs: include xattr.h from fs/nfs/nfs3proc.c
cpuset: update MAINTAINERS entry
arm, pm, vmpressure: add missing slab.h includes
Pull workqueue fixes from Tejun Heo:
"Two workqueue fixes. One for an unlikely but possible critical bug
during kworker shutdown and the other to make lockdep names a bit more
descriptive"
* 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: ensure @task is valid across kthread_stop()
workqueue: add args to workqueue lockdep name
The generic sched_clock registration function was previously
done lockless, due to the fact that it was expected to be called
only once. However, now there are systems that may register
multiple sched_clock sources, for which the lack of locking has
casued problems:
If two sched_clock sources are registered we may end up in a
situation where a call to sched_clock() may be accessing the
epoch cycle count for the old counter and the cycle count for the
new counter. This can lead to confusing results where
sched_clock() values jump and then are reset to 0 (due to the way
the registration function forces the epoch_ns to be 0).
Fix this by reorganizing the registration function to hold the
seqlock for as short a time as possible while we update the
clock_data structure for a new counter. We also put any
accumulated time into epoch_ns instead of resetting the time to
0 so that the clock doesn't reset after each successful
registration.
[jstultz: Added extra context to the commit message]
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently, there's nothing preventing cgroup_enable_task_cg_lists()
from missing set PF_EXITING and race against cgroup_exit(). Depending
on the timing, cgroup_exit() may finish with the task still linked on
css_set leading to list corruption. Fix it by grabbing siglock in
cgroup_enable_task_cg_lists() so that PF_EXITING is guaranteed to be
visible.
This whole on-demand cg_list optimization is extremely fragile and has
ample possibility to lead to bugs which can cause things like
once-a-year oops during boot. I'm wondering whether the better
approach would be just adding "cgroup_disable=all" handling which
disables the whole cgroup rather than tempting fate with this
on-demand craziness.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
When a kworker should die, the kworkre is notified through WORKER_DIE
flag instead of kthread_should_stop(). This, IIRC, is primarily to
keep the test synchronized inside worker_pool lock. WORKER_DIE is
first set while holding pool->lock, the lock is dropped and
kthread_stop() is called.
Unfortunately, this means that there's a slight chance that the target
kworker may see WORKER_DIE before kthread_stop() finishes and exits
and frees the target task before or during kthread_stop().
Fix it by pinning the target task before setting WORKER_DIE and
putting it after kthread_stop() is done.
tj: Improved patch description and comment. Moved pinning above
WORKER_DIE for better signify what it's protecting.
CC: stable@vger.kernel.org
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
My rework of handling of notification events (namely commit 7053aee26a35
"fsnotify: do not share events between notification groups") broke
sending of cookies with inotify events. We didn't propagate the value
passed to fsnotify() properly and passed 4 uninitialized bytes to
userspace instead (so it is also an information leak). Sadly I didn't
notice this during my testing because inotify cookies aren't used very
much and LTP inotify tests ignore them.
Fix the problem by passing the cookie value properly.
Fixes: 7053aee26a3548ebaba046ae2e52396ccf56ac6c
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This is not a buffer overflow in the traditional sense: we don't
overflow any *kernel* buffers, but we do mis-count the amount of data we
copy back to user space for the SYSLOG_ACTION_READ_ALL case.
In particular, if the user buffer is too small to hold everything, and
*if* there is a continuation line at just the right place, we can end up
giving the user more data than he asked for.
The reason is that we first count up the number of bytes all the log
records contains, then we walk the records again until we've skipped the
records at the beginning that won't fit, and then we walk the rest of
the records and copy them to the user space buffer.
And in between that "skip the initial records that won't fit" and the
"copy the records that *will* fit to user space", we reset the 'prev'
variable that contained the record information for the last record not
copied. That meant that when we started copying to user space, we now
had a different character count than what we had originally calculated
in the first record walk-through.
The fix is to simply not clear the 'prev' flags value (in both cases
where we had the same logic: syslog_print_all and kmsg_dump_get_buffer:
the latter is used for pstore-like dumping)
Reported-and-tested-by: Debabrata Banerjee <dbanerje@akamai.com>
Acked-by: Kay Sievers <kay@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull irq update from Thomas Gleixner:
"Fix from the urgent branch: a trivial oneliner adding the missing
Kconfig dependency curing build failures which have been discovered by
several build robots.
The update in the irq-core branch provides a new function in the
irq/devres code, which is a prerequisite for driver developers to get
rid of boilerplate code all over the place.
Not a bugfix, but it has zero impact on the current kernel due to the
lack of users. It's simpler to provide the infrastructure to
interested parties via your tree than fulfilling the wishlist of
driver maintainers on which particular commit or tag this should be
based on"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Add missing irq_to_desc export for CONFIG_SPARSE_IRQ=n
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Add devm_request_any_context_irq()
Pull timer fixes from Thomas Gleixner:
"The following trilogy of patches brings you:
- fix for a long standing math overflow issue with HZ < 60
- an onliner fix for a corner case in the dreaded tick broadcast
mechanism affecting a certain range of AMD machines which are
infested with the infamous automagic C1E power control misfeature
- a fix for one of the ARM platforms which allows the kernel to
proceed and boot instead of stupidly panicing for no good reason.
The patch is slightly larger than necessary, but it's less ugly
than the alternative 5 liner"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick: Clear broadcast pending bit when switching to oneshot
clocksource: Kona: Print warning rather than panic
time: Fix overflow when HZ is smaller than 60
AMD systems which use the C1E workaround in the amd_e400_idle routine
trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.
The reason is that the idle routine of those AMD systems switches the
cpu into forced broadcast mode early on before the newly brought up
CPU can switch over to high resolution / NOHZ mode. The timer related
CPU1 bringup looks like this:
clockevent_register_device(local_apic);
tick_setup(local_apic);
...
idle()
tick_broadcast_on_off(FORCE);
tick_broadcast_oneshot_control(ENTER)
cpumask_set(cpu, broadcast_oneshot_mask);
halt();
Now the broadcast interrupt on CPU0 sets CPU1 in the
broadcast_pending_mask and wakes CPU1. So CPU1 continues:
local_apic_timer_interrupt()
tick_handle_periodic();
softirq()
tick_init_highres();
cpumask_clr(cpu, broadcast_oneshot_mask);
tick_broadcast_oneshot_control(ENTER)
WARN_ON(cpumask_test(cpu, broadcast_pending_mask);
So while we remove CPU1 from the broadcast_oneshot_mask when we switch
over to highres mode, we do not clear the pending bit, which then
triggers the warning when we go back to idle.
The reason why this is only visible on C1E affected AMD systems is
that the other machines enter the deep sleep states via
acpi_idle/intel_idle and exit the broadcast mode before executing the
remote triggered local_apic_timer_interrupt. So the pending bit is
already cleared when the switch over to highres mode is clearing the
oneshot mask.
The solution is simple: Clear the pending bit together with the mask
bit when we switch over to highres mode.
Stanislaw came up independently with the same patch by enforcing the
C1E workaround and debugging the fallout. I picked mine, because mine
has a changelog :)
Reported-by: poma <pomidorabelisima@gmail.com>
Debugged-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Justin M. Forbes <jforbes@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This reverts commit ab3f5faa6255a0eb4f832675507d9e295ca7e9ba.
Explanation from Hugh:
It's because more thorough testing, by others here, found that it
wasn't always solving the problem: so I asked Tejun privately to
hold off from sending it in, until we'd worked out why not.
Most of our testing being on a v3,11-based kernel, it was perfectly
possible that the problem was merely our own e.g. missing Tejun's
8a2b75384444 ("workqueue: fix ordered workqueues in NUMA setups").
But that turned out not to be enough to fix it either. Then Filipe
pointed out how percpu_ref_kill_and_confirm() uses call_rcu_sched()
before we ever get to put the offline on to the workqueue: by the
time we get to the workqueue, the ordering has already been lost.
So, thanks for the Acks, but I'm afraid that this ordered workqueue
solution is just not good enough: we should simply forget that patch
and provide a different answer."
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Each sub-buffer (buffer page) has a full 64 bit timestamp. The events on
that page use a 27 bit delta against that timestamp in order to save on
bits written to the ring buffer. If the time between events is larger than
what the 27 bits can hold, a "time extend" event is added to hold the
entire 64 bit timestamp again and the events after that hold a delta from
that timestamp.
As a "time extend" is always paired with an event, it is logical to just
allocate the event with the time extend, to make things a bit more efficient.
Unfortunately, when the pairing code was written, it removed the "delta = 0"
from the first commit on a page, causing the events on the page to be
slightly skewed.
Fixes: 69d1b839f7ee "ring-buffer: Bind time extend and data events together"
Cc: stable@vger.kernel.org # 2.6.37+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Setup cgroupfs like this:
# mount -t cgroup -o cpuacct xxx /cgroup
# mkdir /cgroup/sub1
# mkdir /cgroup/sub2
Then run these two commands:
# for ((; ;)) { mkdir /cgroup/sub1/tmp && rmdir /mnt/sub1/tmp; } &
# for ((; ;)) { mkdir /cgroup/sub2/tmp && rmdir /mnt/sub2/tmp; } &
After seconds you may see this warning:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 25243 at lib/idr.c:527 sub_remove+0x87/0x1b0()
idr_remove called for id=6 which is not allocated.
...
Call Trace:
[<ffffffff8156063c>] dump_stack+0x7a/0x96
[<ffffffff810591ac>] warn_slowpath_common+0x8c/0xc0
[<ffffffff81059296>] warn_slowpath_fmt+0x46/0x50
[<ffffffff81300aa7>] sub_remove+0x87/0x1b0
[<ffffffff810f3f02>] ? css_killed_work_fn+0x32/0x1b0
[<ffffffff81300bf5>] idr_remove+0x25/0xd0
[<ffffffff810f2bab>] cgroup_destroy_css_killed+0x5b/0xc0
[<ffffffff810f4000>] css_killed_work_fn+0x130/0x1b0
[<ffffffff8107cdbc>] process_one_work+0x26c/0x550
[<ffffffff8107eefe>] worker_thread+0x12e/0x3b0
[<ffffffff81085f96>] kthread+0xe6/0xf0
[<ffffffff81570bac>] ret_from_fork+0x7c/0xb0
---[ end trace 2d1577ec10cf80d0 ]---
It's because allocating/removing cgroup ID is not properly synchronized.
The bug was introduced when we converted cgroup_ida to cgroup_idr.
While synchronization is already done inside ida_simple_{get,remove}(),
users are responsible for concurrent calls to idr_{alloc,remove}().
tj: Refreshed on top of b58c89986a77 ("cgroup: fix error return from
cgroup_create()").
Fixes: 4e96ee8e981b ("cgroup: convert cgroup_ida to cgroup_idr")
Cc: <stable@vger.kernel.org> #3.12+
Reported-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In allmodconfig builds for sparc and any other arch which does
not set CONFIG_SPARSE_IRQ, the following will be seen at modpost:
CC [M] lib/cpu-notifier-error-inject.o
CC [M] lib/pm-notifier-error-inject.o
ERROR: "irq_to_desc" [drivers/gpio/gpio-mcp23s08.ko] undefined!
make[2]: *** [__modpost] Error 1
This happens because commit 3911ff30f5 ("genirq: export
handle_edge_irq() and irq_to_desc()") added one export for it, but
there were actually two instances of it, in an if/else clause for
CONFIG_SPARSE_IRQ. Add the second one.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: stable@vger.kernel.org # 3.4+
Link: http://lkml.kernel.org/r/1392057610-11514-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Integration of cpuidle with the scheduler requires that the idle loop be
closely integrated with the scheduler proper. Moving cpu/idle.c into the
sched directory will allow for a smoother integration, and eliminate a
subdirectory which contained only one source file.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401301102210.1652@knanqh.ubzr
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to integrate cpuidle with the scheduler, we must have a better
proximity in the core code with what cpuidle is doing and not delegate
such interaction to arch code.
Architectures implementing arch_cpu_idle() should simply enter
a cheap idle mode in the absence of a proper cpuidle driver.
In both cases i.e. whether it is a cpuidle driver or the default
arch_cpu_idle(), the calling convention expects IRQs to be disabled
on entry and enabled on exit. There is a warning in place already but
let's add a forced IRQ enable here as well. This will allow for
removing the forced IRQ enable some implementations do locally and
allowing for the warning to trig.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401291526320.1652@knanqh.ubzr
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tracking rq->max_idle_balance_cost and sd->max_newidle_lb_cost.
It's useful to know these values in debug mode.
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/52E0F3BF.5020904@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since is_same_group() is only used in the group scheduling code, there is
no need to define it outside CONFIG_FAIR_GROUP_SCHED.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1391005773-29493-1-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch both merged idle_balance() and pre_schedule() and pushes
both of them into pick_next_task().
Conceptually pre_schedule() and idle_balance() are rather similar,
both are used to pull more work onto the current CPU.
We cannot however first move idle_balance() into pre_schedule_fair()
since there is no guarantee the last runnable task is a fair task, and
thus we would miss newidle balances.
Similarly, the dl and rt pre_schedule calls must be ran before
idle_balance() since their respective tasks have higher priority and
it would not do to delay their execution searching for less important
tasks first.
However, by noticing that pick_next_tasks() already traverses the
sched_class hierarchy in the right order, we can get the right
behaviour and do away with both calls.
We must however change the special case optimization to also require
that prev is of sched_class_fair, otherwise we can miss doing a dl or
rt pull where we needed one.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-a8k6vvaebtn64nie345kx1je@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The idle post_schedule flag is just a vile waste of time, furthermore
it appears unneeded, move the idle_enter_fair() call into
pick_next_task_idle().
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: alex.shi@linaro.org
Cc: mingo@kernel.org
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-aljykihtxJt3mkokxi0qZurb@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit 2f36825b1 ("sched: Next buddy hint on sleep and preempt
path") it is likely we pick a new task from the same cgroup, doing a put
and then set on all intermediate entities is a waste of time, so try to
avoid this.
Measured using:
mount nodev /cgroup -t cgroup -o cpu
cd /cgroup
mkdir a; cd a
mkdir b; cd b
mkdir c; cd c
echo $$ > tasks
perf stat --repeat 10 -- taskset 1 perf bench sched pipe
PRE : 4.542422684 seconds time elapsed ( +- 0.33% )
POST: 4.389409991 seconds time elapsed ( +- 0.32% )
Which shows a significant improvement of ~3.5%
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to avoid having to do put/set on a whole cgroup hierarchy
when we context switch, push the put into pick_next_task() so that
both operations are in the same function. Further changes then allow
us to possibly optimize away redundant work.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Track depth in cgroup tree, this is useful for things like
find_matching_se() where you need to get to a common parent of two
sched entities.
Keeping the depth avoids having to calculate it on the spot, which
saves a number of possible cache-misses.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1328936700.2476.17.camel@laptop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
idle_balance() modifies the rq->idle_stamp field, making this information
shared across core.c and fair.c.
As we know if the cpu is going to idle or not with the previous patch, let's
encapsulate the rq->idle_stamp information in core.c by moving it up to the
caller.
The idle_balance() function returns true in case a balancing occured and the
cpu won't be idle, false if no balance happened and the cpu is going idle.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: alex.shi@linaro.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1389949444-14821-3-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The scheduler main function 'schedule()' checks if there are no more tasks
on the runqueue. Then it checks if a task should be pulled in the current
runqueue in idle_balance() assuming it will go to idle otherwise.
But idle_balance() releases the rq->lock in order to look up the sched
domains and takes the lock again right after. That opens a window where
another cpu may put a task in our runqueue, so we won't go to idle but
we have filled the idle_stamp, thinking we will.
This patch closes the window by checking if the runqueue has been modified
but without pulling a task after taking the lock again, so we won't go to idle
right after in the __schedule() function.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: alex.shi@linaro.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1389949444-14821-2-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
As patch "sched: Move the priority specific bits into a new header file" exposes
the priority related macros in linux/sched/prio.h, we don't have to implement
task_nice() in kernel/sched/core.c any more.
This patch implements it in linux/sched/sched.h as static inline function,
saving the kernel stack and enhancing performance a bit.
Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: clark.williams@gmail.com
Cc: rostedt@goodmis.org
Cc: raistlin@linux.it
Cc: juri.lelli@gmail.com
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1390878045-7096-1-git-send-email-yangds.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When p is current and it's not of dl class, then there are no other
dl taks in the rq. If we had had pushable tasks in some other rq,
they would have been pushed earlier. So, skip "p == rq->curr" case.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Acked-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140128072421.32315.25300.stgit@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cgroup_cfts_commit() walks the cgroup hierarchy that the target
subsystem is attached to and tries to apply the file changes. Due to
the convolution with inode locking, it can't keep cgroup_mutex locked
while iterating. It currently holds only RCU read lock around the
actual iteration and then pins the found cgroup using dget().
Unfortunately, this is incorrect. Although the iteration does check
cgroup_is_dead() before invoking dget(), there's nothing which
prevents the dentry from going away inbetween. Note that this is
different from the usual css iterations where css_tryget() is used to
pin the css - css_tryget() tests whether the css can be pinned and
fails if not.
The problem can be solved by simply holding cgroup_mutex instead of
RCU read lock around the iteration, which actually reduces LOC.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
cgroup_create() was returning 0 after allocation failures. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
When cgroup_mount() fails to allocate an id for the root, it didn't
set ret before jumping to unlock_drop ending up returning 0 after a
failure. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
Sometimes the cleanup after memcg hierarchy testing gets stuck in
mem_cgroup_reparent_charges(), unable to bring non-kmem usage down to 0.
There may turn out to be several causes, but a major cause is this: the
workitem to offline parent can get run before workitem to offline child;
parent's mem_cgroup_reparent_charges() circles around waiting for the
child's pages to be reparented to its lrus, but it's holding cgroup_mutex
which prevents the child from reaching its mem_cgroup_reparent_charges().
Just use an ordered workqueue for cgroup_destroy_wq.
tj: Committing as the temporary fix until the reverse dependency can
be removed from memcg. Comment updated accordingly.
Fixes: e5fca243abae ("cgroup: use a dedicated workqueue for cgroup destruction")
Suggested-by: Filipe Brandenburger <filbranden@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Tejun Heo <tj@kernel.org>
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This changes 'do_execve()' to get the executable name as a 'struct
filename', and to free it when it is done. This is what the normal
users want, and it simplifies and streamlines their error handling.
The controlled lifetime of the executable name also fixes a
use-after-free problem with the trace_sched_process_exec tracepoint: the
lifetime of the passed-in string for kernel users was not at all
obvious, and the user-mode helper code used UMH_WAIT_EXEC to serialize
the pathname allocation lifetime with the execve() having finished,
which in turn meant that the trace point that happened after
mm_release() of the old process VM ended up using already free'd memory.
To solve the kernel string lifetime issue, this simply introduces
"getname_kernel()" that works like the normal user-space getname()
function, except with the source coming from kernel memory.
As Oleg points out, this also means that we could drop the tcomm[] array
from 'struct linux_binprm', since the pathname lifetime now covers
setup_new_exec(). That would be a separate cleanup.
Reported-by: Igor Zhbanov <i.zhbanov@samsung.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The generic_chip.c uses interfaces from irq_domain.c which is
controlled by the IRQ_DOMAIN config option, but there is no Kconfig
dependency so the build can fail:
linux/kernel/irq/generic-chip.c:400:11: error:
'irq_domain_xlate_onetwocell' undeclared here (not in a function)
Select IRQ_DOMAIN when GENERIC_IRQ_CHIP is selected.
Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Link: http://lkml.kernel.org/r/1391129410-54548-2-git-send-email-nitin.a.kamble@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # 3.11+
arch/arm/mach-tegra/pm.c, kernel/power/console.c and mm/vmpressure.c
were somehow getting slab.h indirectly through cgroup.h which in turn
was getting it indirectly through xattr.h. A scheduled cgroup change
drops xattr.h inclusion from cgroup.h and breaks compilation of these
three files. Add explicit slab.h includes to the three files.
A pending cgroup patch depends on this change and it'd be great if
this can be routed through cgroup/for-3.14-fixes branch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-tegra@vger.kernel.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: cgroups@vger.kernel.org
Pull timer/dynticks updates from Ingo Molnar:
"This tree contains misc dynticks updates: a fix and three cleanups"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/nohz: Fix overflow error in scheduler_tick_max_deferment()
nohz_full: fix code style issue of tick_nohz_full_stop_tick
nohz: Get timekeeping max deferment outside jiffies_lock
tick: Rename tick_check_idle() to tick_irq_enter()
Pull core debug changes from Ingo Molnar:
"This contains mostly kernel debugging related updates:
- make hung_task detection more configurable to distros
- add final bits for x86 UV NMI debugging, with related KGDB changes
- update the mailing-list of MAINTAINERS entries I'm involved with"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hung_task: Display every hung task warning
sysctl: Add neg_one as a standard constraint
x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured
x86/uv/nmi: Fix Sparse warnings
kgdb/kdb: Fix no KDB config problem
MAINTAINERS: Restore "L: linux-kernel@vger.kernel.org" entries
After commit 9a46ad6d6df3 ("smp: make smp_call_function_many() use logic
similar to smp_call_function_single()"), cfd->cpumask is accessed only
in smp_call_function_many(). So there is no more need to copy it into
cfd->cpumask_ipi before putting csd into the list. The cpumask_ipi
field is obsolete and can be removed.
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Wang YanQing <udknight@gmail.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
