For easier access, less dereferences and more consistent value, store
the group power in update_sg_lb_stats() and use it thereafter. The
actual value in sched_group::sched_group_power::power can change
throughout the load-balance pass if we're unlucky.
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-739xxqkyvftrhnh9ncudutc7@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since we already compute (but don't store) the sgs load_per_task value
in update_sg_lb_stats() we might as well store it and not re-compute
it later on.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-ym1vmljiwbzgdnnrwp9azftq@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We can shrink sg_lb_stats because rq::nr_running is an unsigned int
and cpu numbers are 'int'
Before:
sgs: /* size: 72, cachelines: 2, members: 10 */
sds: /* size: 184, cachelines: 3, members: 7 */
After:
sgs: /* size: 56, cachelines: 1, members: 10 */
sds: /* size: 152, cachelines: 3, members: 7 */
Further we can avoid clearing all of sds since we do a total
clear/assignment of sg_stats in update_sg_lb_stats() with exception of
busiest_stat.avg_load which is referenced in update_sd_pick_busiest().
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-0klzmz9okll8wc0nsudguc9p@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no reason to maintain separate variables for this_group
and busiest_group in sd_lb_stat, except saving some space.
But this structure is always allocated in stack, so this saving
isn't really benificial [peterz: reducing stack space is good; in this
case readability increases enough that I think its still beneficial]
This patch unify these variables, so IMO, readability may be improved.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ Rename this to local -- avoids confusion between this_cpu and the C++ this pointer. ]
Reviewed-by: Paul Turner <pjt@google.com>
[ Lots of style edits, a few fixes and a rename. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now checking whether this cpu is appropriate to balance or not
is embedded into update_sg_lb_stats() and this checking has no direct
relationship to this function. There is not enough reason to place
this checking at update_sg_lb_stats(), except saving one iteration
for sched_group_cpus.
In this patch, I factor out this checking to should_we_balance() function.
And before doing actual work for load_balancing, check whether this cpu is
appropriate to balance via should_we_balance(). If this cpu is not
a candidate for balancing, it quit the work immediately.
With this change, we can save two memset cost and can expect better
compiler optimization.
Below is result of this patch.
* Vanilla *
text data bss dec hex filename
34499 1136 116 35751 8ba7 kernel/sched/fair.o
* Patched *
text data bss dec hex filename
34243 1136 116 35495 8aa7 kernel/sched/fair.o
In addition, rename @balance to @continue_balancing in order to represent
its purpose more clearly.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ s/should_balance/continue_balancing/g ]
Reviewed-by: Paul Turner <pjt@google.com>
[ Made style changes and a fix in should_we_balance(). ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current throttling code triggers WARN below via following
workload (only hit on AMD machine with 48 CPUs):
# while [ 1 ]; do perf record perf bench sched messaging; done
WARNING: at arch/x86/kernel/cpu/perf_event.c:1054 x86_pmu_start+0xc6/0x100()
SNIP
Call Trace:
<IRQ> [<ffffffff815f62d6>] dump_stack+0x19/0x1b
[<ffffffff8105f531>] warn_slowpath_common+0x61/0x80
[<ffffffff8105f60a>] warn_slowpath_null+0x1a/0x20
[<ffffffff810213a6>] x86_pmu_start+0xc6/0x100
[<ffffffff81129dd2>] perf_adjust_freq_unthr_context.part.75+0x182/0x1a0
[<ffffffff8112a058>] perf_event_task_tick+0xc8/0xf0
[<ffffffff81093221>] scheduler_tick+0xd1/0x140
[<ffffffff81070176>] update_process_times+0x66/0x80
[<ffffffff810b9565>] tick_sched_handle.isra.15+0x25/0x60
[<ffffffff810b95e1>] tick_sched_timer+0x41/0x60
[<ffffffff81087c24>] __run_hrtimer+0x74/0x1d0
[<ffffffff810b95a0>] ? tick_sched_handle.isra.15+0x60/0x60
[<ffffffff81088407>] hrtimer_interrupt+0xf7/0x240
[<ffffffff81606829>] smp_apic_timer_interrupt+0x69/0x9c
[<ffffffff8160569d>] apic_timer_interrupt+0x6d/0x80
<EOI> [<ffffffff81129f74>] ? __perf_event_task_sched_in+0x184/0x1a0
[<ffffffff814dd937>] ? kfree_skbmem+0x37/0x90
[<ffffffff815f2c47>] ? __slab_free+0x1ac/0x30f
[<ffffffff8118143d>] ? kfree+0xfd/0x130
[<ffffffff81181622>] kmem_cache_free+0x1b2/0x1d0
[<ffffffff814dd937>] kfree_skbmem+0x37/0x90
[<ffffffff814e03c4>] consume_skb+0x34/0x80
[<ffffffff8158b057>] unix_stream_recvmsg+0x4e7/0x820
[<ffffffff814d5546>] sock_aio_read.part.7+0x116/0x130
[<ffffffff8112c10c>] ? __perf_sw_event+0x19c/0x1e0
[<ffffffff814d5581>] sock_aio_read+0x21/0x30
[<ffffffff8119a5d0>] do_sync_read+0x80/0xb0
[<ffffffff8119ac85>] vfs_read+0x145/0x170
[<ffffffff8119b699>] SyS_read+0x49/0xa0
[<ffffffff810df516>] ? __audit_syscall_exit+0x1f6/0x2a0
[<ffffffff81604a19>] system_call_fastpath+0x16/0x1b
---[ end trace 622b7e226c4a766a ]---
The reason is a race in perf_event_task_tick() throttling code.
The race flow (simplified code):
- perf_throttled_count is per cpu variable and is
CPU throttling flag, here starting with 0
- perf_throttled_seq is sequence/domain for allowed
count of interrupts within the tick, gets increased
each tick
on single CPU (CPU bounded event):
... workload
perf_event_task_tick:
|
| T0 inc(perf_throttled_seq)
| T1 needs_unthr = xchg(perf_throttled_count, 0) == 0
tick gets interrupted:
... event gets throttled under new seq ...
T2 last NMI comes, event is throttled - inc(perf_throttled_count)
back to tick:
| perf_adjust_freq_unthr_context:
|
| T3 unthrottling is skiped for event (needs_unthr == 0)
| T4 event is stop and started via freq adjustment
|
tick ends
... workload
... no sample is hit for event ...
perf_event_task_tick:
|
| T5 needs_unthr = xchg(perf_throttled_count, 0) != 0 (from T2)
| T6 unthrottling is done on event (interrupts == MAX_INTERRUPTS)
| event is already started (from T4) -> WARN
Fixing this by not checking needs_unthr again and thus
check all events for unthrottling.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Reported-by: Jan Stancek <jstancek@redhat.com>
Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1377355554-8934-1-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because RCU's quiescent-state-forcing mechanism is used to drive the
full-system-idle state machine, and because this mechanism is executed
by RCU's grace-period kthreads, this commit forces these kthreads to
run on the timekeeping CPU (tick_do_timer_cpu). To do otherwise would
mean that the RCU grace-period kthreads would force the system into
non-idle state every time they drove the state machine, which would
be just a bit on the futile side.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit adds the state machine that takes the per-CPU idle data
as input and produces a full-system-idle indication as output. This
state machine is driven out of RCU's quiescent-state-forcing
mechanism, which invokes rcu_sysidle_check_cpu() to collect per-CPU
idle state and then rcu_sysidle_report() to drive the state machine.
The full-system-idle state is sampled using rcu_sys_is_idle(), which
also drives the state machine if RCU is idle (and does so by forcing
RCU to become non-idle). This function returns true if all but the
timekeeping CPU (tick_do_timer_cpu) are idle and have been idle long
enough to avoid memory contention on the full_sysidle_state state
variable. The rcu_sysidle_force_exit() may be called externally
to reset the state machine back into non-idle state.
For large systems the state machine is driven out of RCU's
force-quiescent-state logic, which provides good scalability at the price
of millisecond-scale latencies on the transition to full-system-idle
state. This is not so good for battery-powered systems, which are usually
small enough that they don't need to care about scalability, but which
do care deeply about energy efficiency. Small systems therefore drive
the state machine directly out of the idle-entry code. The number of
CPUs in a "small" system is defined by a new NO_HZ_FULL_SYSIDLE_SMALL
Kconfig parameter, which defaults to 8. Note that this is a build-time
definition.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
[ paulmck: Use true and false for boolean constants per Lai Jiangshan. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Simplify logic and provide better comments for memory barriers,
based on review comments and questions by Lai Jiangshan. ]
nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and
CAP_SETGID. For the existing users it doesn't noticably simplify things and
from the suggested patches I have seen it encourages people to do the wrong
thing. So remove nsown_capable.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
I goofed when I made unshare(CLONE_NEWPID) only work in a
single-threaded process. There is no need for that requirement and in
fact I analyzied things right for setns. The hard requirement
is for tasks that share a VM to all be in the pid namespace and
we properly prevent that in do_fork.
Just to be certain I took a look through do_wait and
forget_original_parent and there are no cases that make it any harder
for children to be in the multiple pid namespaces than it is for
children to be in the same pid namespace. I also performed a check to
see if there were in uses of task->nsproxy_pid_ns I was not familiar
with, but it is only used when allocating a new pid for a new task,
and in checks to prevent craziness from happening.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Since all of the memory hotplug operations have to be carried out
under device_hotplug_lock, they won't need to acquire pm_mutex if
device_hotplug_lock is held around hibernation.
For this reason, make the hibernation code acquire
device_hotplug_lock after freezing user space processes and
release it before thawing them. At the same tim drop the
lock_system_sleep() and unlock_system_sleep() calls from
lock_memory_hotplug() and unlock_memory_hotplug(), respectively.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
The hibernation core uses special memory bitmaps during image
creation and restoration and traditionally those bitmaps are
allocated before freezing tasks, because in the past GFP_KERNEL
allocations might not work after all tasks had been frozen.
However, this is an anachronism, because hibernation_snapshot()
now calls hibernate_preallocate_memory() which allocates memory
for the image upfront anyway, so the memory bitmaps may be
allocated after freezing user space safely.
For this reason, move all of the create_basic_memory_bitmaps()
calls after freeze_processes() and all of the corresponding
free_basic_memory_bitmaps() calls before thaw_processes().
This will allow us to hold device_hotplug_lock around hibernation
without the need to worry about freezing issues with user space
processes attempting to acquire it via sysfs attributes after the
creation of memory bitmaps and before the freezing of tasks.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Pull networking fixes from David Miller:
1) There was a simplification in the ipv6 ndisc packet sending
attempted here, which avoided using memory accounting on the
per-netns ndisc socket for sending NDISC packets. It did fix some
important issues, but it causes regressions so it gets reverted here
too. Specifically, the problem with this change is that the IPV6
output path really depends upon there being a valid skb->sk
attached.
The reason we want to do this change in some form when we figure out
how to do it right, is that if a device goes down the ndisc_sk
socket send queue will fill up and block NDISC packets that we want
to send to other devices too. That's really bad behavior.
Hopefully Thomas can come up with a better version of this change.
2) Fix a severe TCP performance regression by reverting a change made
to dev_pick_tx() quite some time ago. From Eric Dumazet.
3) TIPC returns wrongly signed error codes, fix from Erik Hugne.
4) Fix OOPS when doing IPSEC over ipv4 tunnels due to orphaning the
skb->sk too early. Fix from Li Hongjun.
5) RAW ipv4 sockets can use the wrong routing key during lookup, from
Chris Clark.
6) Similar to #1 revert an older change that tried to use plain
alloc_skb() for SYN/ACK TCP packets, this broke the netfilter owner
mark which needs to see the skb->sk for such frames. From Phil
Oester.
7) BNX2x driver bug fixes from Ariel Elior and Yuval Mintz,
specifically in the handling of virtual functions.
8) IPSEC path error propagations to sockets is not done properly when
we have v4 in v6, and v6 in v4 type rules. Fix from Hannes Frederic
Sowa.
9) Fix missing channel context release in mac80211, from Johannes Berg.
10) Fix network namespace handing wrt. SCM_RIGHTS, from Andy
Lutomirski.
11) Fix usage of bogus NAPI weight in jme, netxen, and ps3_gelic
drivers. From Michal Schmidt.
12) Hopefully a complete and correct fix for the genetlink dump locking
and module reference counting. From Pravin B Shelar.
13) sk_busy_loop() must do a cpu_relax(), from Eliezer Tamir.
14) Fix handling of timestamp offset when restoring a snapshotted TCP
socket. From Andrew Vagin.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (44 commits)
net: fec: fix time stamping logic after napi conversion
net: bridge: convert MLDv2 Query MRC into msecs_to_jiffies for max_delay
mISDN: return -EINVAL on error in dsp_control_req()
net: revert 8728c544a9 ("net: dev_pick_tx() fix")
Revert "ipv6: Don't depend on per socket memory for neighbour discovery messages"
ipv4 tunnels: fix an oops when using ipip/sit with IPsec
tipc: set sk_err correctly when connection fails
tcp: tcp_make_synack() should use sock_wmalloc
bridge: separate querier and query timer into IGMP/IPv4 and MLD/IPv6 ones
ipv6: Don't depend on per socket memory for neighbour discovery messages
ipv4: sendto/hdrincl: don't use destination address found in header
tcp: don't apply tsoffset if rcv_tsecr is zero
tcp: initialize rcv_tstamp for restored sockets
net: xilinx: fix memleak
net: usb: Add HP hs2434 device to ZLP exception table
net: add cpu_relax to busy poll loop
net: stmmac: fixed the pbl setting with DT
genl: Hold reference on correct module while netlink-dump.
genl: Fix genl dumpit() locking.
xfrm: Fix potential null pointer dereference in xdst_queue_output
...
Remove the test for the impossible case where tsk->nsproxy == NULL. Fork
will never be called with tsk->nsproxy == NULL.
Only call get_nsproxy when we don't need to generate a new_nsproxy,
and mark the case where we don't generate a new nsproxy as likely.
Remove the code to drop an unnecessarily acquired nsproxy value.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Serge Hallyn <serge.hallyn@ubuntu.com> writes:
> Since commit af4b8a83ad it's been
> possible to get into a situation where a pidns reaper is
> <defunct>, reparented to host pid 1, but never reaped. How to
> reproduce this is documented at
>
> https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1168526
> (and see
> https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1168526/comments/13)
> In short, run repeated starts of a container whose init is
>
> Process.exit(0);
>
> sysrq-t when such a task is playing zombie shows:
>
> [ 131.132978] init x ffff88011fc14580 0 2084 2039 0x00000000
> [ 131.132978] ffff880116e89ea8 0000000000000002 ffff880116e89fd8 0000000000014580
> [ 131.132978] ffff880116e89fd8 0000000000014580 ffff8801172a0000 ffff8801172a0000
> [ 131.132978] ffff8801172a0630 ffff88011729fff0 ffff880116e14650 ffff88011729fff0
> [ 131.132978] Call Trace:
> [ 131.132978] [<ffffffff816f6159>] schedule+0x29/0x70
> [ 131.132978] [<ffffffff81064591>] do_exit+0x6e1/0xa40
> [ 131.132978] [<ffffffff81071eae>] ? signal_wake_up_state+0x1e/0x30
> [ 131.132978] [<ffffffff8106496f>] do_group_exit+0x3f/0xa0
> [ 131.132978] [<ffffffff810649e4>] SyS_exit_group+0x14/0x20
> [ 131.132978] [<ffffffff8170102f>] tracesys+0xe1/0xe6
>
> Further debugging showed that every time this happened, zap_pid_ns_processes()
> started with nr_hashed being 3, while we were expecting it to drop to 2.
> Any time it didn't happen, nr_hashed was 1 or 2. So the reaper was
> waiting for nr_hashed to become 2, but free_pid() only wakes the reaper
> if nr_hashed hits 1.
The issue is that when the task group leader of an init process exits
before other tasks of the init process when the init process finally
exits it will be a secondary task sleeping in zap_pid_ns_processes and
waiting to wake up when the number of hashed pids drops to two. This
case waits forever as free_pid only sends a wake up when the number of
hashed pids drops to 1.
To correct this the simple strategy of sending a possibly unncessary
wake up when the number of hashed pids drops to 2 is adopted.
Sending one extraneous wake up is relatively harmless, at worst we
waste a little cpu time in the rare case when a pid namespace
appropaches exiting.
We can detect the case when the pid namespace drops to just two pids
hashed race free in free_pid.
Dereferencing pid_ns->child_reaper with the pidmap_lock held is safe
without out the tasklist_lock because it is guaranteed that the
detach_pid will be called on the child_reaper before it is freed and
detach_pid calls __change_pid which calls free_pid which takes the
pidmap_lock. __change_pid only calls free_pid if this is the
last use of the pid. For a thread that is not the thread group leader
the threads pid will only ever have one user because a threads pid
is not allowed to be the pid of a process, of a process group or
a session. For a thread that is a thread group leader all of
the other threads of that process will be reaped before it is allowed
for the thread group leader to be reaped ensuring there will only
be one user of the threads pid as a process pid. Furthermore
because the thread is the init process of a pid namespace all of the
other processes in the pid namespace will have also been already freed
leading to the fact that the pid will not be used as a session pid or
a process group pid for any other running process.
CC: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Tested-by: Serge Hallyn <serge.hallyn@canonical.com>
Reported-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Pull cgroup fix from Tejun Heo:
"During the percpu reference counting update which was merged during
v3.11-rc1, the cgroup destruction path was updated so that a cgroup in
the process of dying may linger on the children list, which was
necessary as the cgroup should still be included in child/descendant
iteration while percpu ref is being killed.
Unfortunately, I forgot to update cgroup destruction path accordingly
and cgroup destruction may fail spuriously with -EBUSY due to
lingering dying children even when there's no live child left - e.g.
"rmdir parent/child parent" will usually fail.
This can be easily fixed by iterating through the children list to
verify that there's no live child left. While this is very late in
the release cycle, this bug is very visible to userland and I believe
the fix is relatively safe.
Thanks Hugh for spotting and providing fix for the issue"
* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: fix rmdir EBUSY regression in 3.11
The event stream is not always parsable because the format of a sample
is dependent on the sample_type of the selected event. When there is
more than one selected event and the sample_types are not the same then
parsing becomes problematic. A sample can be matched to its selected
event using the ID that is allocated when the event is opened.
Unfortunately, to get the ID from the sample means first parsing it.
This patch adds a new sample format bit PERF_SAMPLE_IDENTIFER that puts
the ID at a fixed position so that the ID can be retrieved without
parsing the sample. For sample events, that is the first position
immediately after the header. For non-sample events, that is the last
position.
In this respect parsing samples requires that the sample_type and ID
values are recorded. For example, perf tools records struct
perf_event_attr and the IDs within the perf.data file. Those must be
read first before it is possible to parse samples found later in the
perf.data file.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1377591794-30553-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
On 3.11-rc we are seeing cgroup directories left behind when they should
have been removed. Here's a trivial reproducer:
cd /sys/fs/cgroup/memory
mkdir parent parent/child; rmdir parent/child parent
rmdir: failed to remove `parent': Device or resource busy
It's because cgroup_destroy_locked() (step 1 of destruction) leaves
cgroup on parent's children list, letting cgroup_offline_fn() (step 2 of
destruction) remove it; but step 2 is run by work queue, which may not
yet have removed the children when parent destruction checks the list.
Fix that by checking through a non-empty list of children: if every one
of them has already been marked CGRP_DEAD, then it's safe to proceed:
those children are invisible to userspace, and should not obstruct rmdir.
(I didn't see any reason to keep the cgrp->children checks under the
unrelated css_set_lock, so moved them out.)
tj: Flattened nested ifs a bit and updated comment so that it's
correct on both for-3.11-fixes and for-3.12.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
If !PREEMPT, a kworker running work items back to back can hog CPU.
This becomes dangerous when a self-requeueing work item which is
waiting for something to happen races against stop_machine. Such
self-requeueing work item would requeue itself indefinitely hogging
the kworker and CPU it's running on while stop_machine would wait for
that CPU to enter stop_machine while preventing anything else from
happening on all other CPUs. The two would deadlock.
Jamie Liu reports that this deadlock scenario exists around
scsi_requeue_run_queue() and libata port multiplier support, where one
port may exclude command processing from other ports. With the right
timing, scsi_requeue_run_queue() can end up requeueing itself trying
to execute an IO which is asked to be retried while another device has
an exclusive access, which in turn can't make forward progress due to
stop_machine.
Fix it by invoking cond_resched() after executing each work item.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jamie Liu <jamieliu@google.com>
References: http://thread.gmane.org/gmane.linux.kernel/1552567
Cc: stable@vger.kernel.org
--
kernel/workqueue.c | 9 +++++++++
1 file changed, 9 insertions(+)
padata_cpu_callback() takes pinst->lock, to avoid taking
an uninitialized lock, register the notifier after it's
initialization.
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Share code between CPU_ONLINE and CPU_DOWN_FAILED, same to
CPU_DOWN_PREPARE and CPU_UP_CANCELED.
It will fix 2 bugs:
"not check the return value of __padata_remove_cpu() and __padata_add_cpu()".
"need add 'break' between CPU_UP_CANCELED and CPU_DOWN_FAILED".
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Correct an issue with /proc/timer_list reported by Holger.
When reading from the proc file with a sufficiently small buffer, 2k so
not really that small, there was one could get hung trying to read the
file a chunk at a time.
The timer_list_start function failed to account for the possibility that
the offset was adjusted outside the timer_list_next.
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Reported-by: Holger Hans Peter Freyther <holger@freyther.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Berke Durak <berke.durak@xiphos.com>
Cc: Jeff Layton <jlayton@redhat.com>
Tested-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org> # 3.10.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ca8bdcaff0 ("cgroup: make cgroup_css() take cgroup_subsys * instead
and allow NULL subsys") missed one conversion in css_from_id(), which
was newly added. As css_from_id() doesn't have any user yet, this
doesn't break anything other than generating a build warning.
Convert it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
nsproxy.pid_ns is *not* the task's pid namespace. The name should clarify
that.
This makes it more obvious that setns on a pid namespace is weird --
it won't change the pid namespace shown in procfs.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rely on the fact that another flavor of the filesystem is already
mounted and do not rely on state in the user namespace.
Verify that the mounted filesystem is not covered in any significant
way. I would love to verify that the previously mounted filesystem
has no mounts on top but there are at least the directories
/proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly
for other filesystems to mount on top of.
Refactor the test into a function named fs_fully_visible and call that
function from the mount routines of proc and sysfs. This makes this
test local to the filesystems involved and the results current of when
the mounts take place, removing a weird threading of the user
namespace, the mount namespace and the filesystems themselves.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
It seems GCC generates a better code in that way, so I changed that statement.
Btw, they have the same semantic, so I'm sending this patch due to performance issues.
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Raphael S.Carvalho <raphael.scarv@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
cgroup_event will be moved to its only user - memcg. Replace
__d_cgrp() usage with css_from_dir(), which is already exported. This
also simplifies the code a bit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Currently, each registered cgroup_event holds an extra reference to
the cgroup. This is a bit weird as events are subsystem specific and
will also be incorrect in the planned unified hierarchy as css
(cgroup_subsys_state) may come and go dynamically across the lifetime
of a cgroup. Holding onto cgroup won't prevent the target css from
going away.
Update cgroup_event to hold onto the css the traget file belongs to
instead of cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
When cgroup files are created, cgroup core automatically prepends the
name of the subsystem as prefix. This patch adds CFTYPE_NO_ which
disables the automatic prefix. This is to work around historical
baggages and shouldn't be used for new files.
This will be used to move "cgroup.event_control" from cgroup core to
memcg.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Glauber Costa <glommer@gmail.com>
cgroup_css() is no longer used in hot paths. Make it take struct
cgroup_subsys * and allow the users to specify NULL subsys to obtain
the dummy_css. This removes open-coded NULL subsystem testing in a
couple users and generally simplifies the code.
After this patch, css_from_dir() also allows NULL @ss and returns the
matching dummy_css. This behavior change doesn't affect its only user
- perf.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
cgroup_css_from_dir() will grow another user. In preparation, make
the following changes.
* All css functions are prefixed with just "css_", rename it to
css_from_dir().
* Take dentry * instead of file * as dentry is what ultimately
identifies a cgroup and file may not always be available. Note that
the function now checkes whether @dentry->d_inode is NULL as the
caller now may specify a negative dentry.
* Make it take cgroup_subsys * instead of integer subsys_id. This
simplifies the function and allows specifying no subsystem for
cgroup->dummy_css.
* Make return section a bit less verbose.
This patch doesn't introduce any behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead. This converts the workqueue bus code to use
the correct field.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull cgroup fix from Tejun Heo:
"A late fix for cgroup.
This fixes a behavior regression visible to userland which was created
by a commit merged during -rc1. While the behavior change isn't too
likely to be noticeable, the fix is relatively low risk and we'll need
to backport it through -stable anyway if the bug gets released"
* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: fix a regression in validating config change
Allow tracer instances to disable tracing by cpu by moving
the static global tracing_cpumask into trace_array.
Link: http://lkml.kernel.org/r/921622317f239bfc2283cac2242647801ef584f2.1375980149.git.azl@google.com
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Alexander Z Lam <azl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Move trace_module_nb under CONFIG_MODULES and kill the dummy
trace_module_notify(). Imho it doesn't make sense to define
"struct notifier_block" and its .notifier_call just to avoid
"ifdef" in event_trace_init(), and all other !CONFIG_MODULES
code has already gone away.
Link: http://lkml.kernel.org/r/20130731173137.GA31043@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Now that event_create_dir() and __trace_add_new_event() always
use the same file_operations we can kill these arguments and
simplify the code.
Link: http://lkml.kernel.org/r/20130731173135.GA31040@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
trace_create_file_ops() allocates the copy of id/filter/format/enable
file_operations to set "f_op->owner = mod" for fops_get().
However after the recent changes there is no reason to prevent rmmod
even if one of these files is opened. A file operation can do nothing
but fail after remove_event_file_dir() clears ->i_private for every
file removed by trace_module_remove_events().
Kill "struct ftrace_module_file_ops" and fix the compilation errors.
Link: http://lkml.kernel.org/r/20130731173132.GA31033@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
init_syscall_trace() can only be called during kernel bootup only, so we can
mark it and the functions it calls as __init.
Link: http://lkml.kernel.org/r/51528E89.6080508@huawei.com
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
No functional change. The comment of function manage_workers()
RETURNS description is obvious wrong, same as the CONTEXT.
Fix it.
Signed-off-by: Libin <huawei.libin@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
No functional change. There are two worker pools for each cpu in
current implementation (one for normal work items and the other for
high priority ones).
tj: Whitespace adjustments.
Signed-off-by: Libin <huawei.libin@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It's not allowed to clear masks of a cpuset if there're tasks in it,
but it's broken:
# mkdir /cgroup/sub
# echo 0 > /cgroup/sub/cpuset.cpus
# echo 0 > /cgroup/sub/cpuset.mems
# echo $$ > /cgroup/sub/tasks
# echo > /cgroup/sub/cpuset.cpus
(should fail)
This bug was introduced by commit 88fa523bff
("cpuset: allow to move tasks to empty cpusets").
tj: Dropped temp bool variables and nestes the conditionals directly.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit drops an unneeded ACCESS_ONCE() and simplifies an "our work
is done" check in _rcu_barrier(). This applies feedback from Linus
(https://lkml.org/lkml/2013/7/26/777) that he gave to similar code
in an unrelated patch.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Fix comment to match code, reported by Lai Jiangshan. ]
Although rcutorture counts CPU-hotplug online failures, it does
not explicitly record which CPUs were having trouble coming online.
This commit therefore emits a console message when online failure occurs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The oldbatch variable in rcu_torture_writer() is stored to, but never
loaded from. This commit therefore removes it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
There are getting to be too many module parameters to permit the current
semi-random order, so this patch orders them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Currently, rcutorture has separate torture_types to test synchronous,
asynchronous, and expedited grace-period primitives. This has
two disadvantages: (1) Three times the number of runs to cover the
combinations and (2) Little testing of concurrent combinations of the
three options. This commit therefore adds a pair of module parameters
that control normal and expedited state, with the default being both
types, randomly selected, by the fakewriter processes, thus reducing
source-code size and increasing test coverage. In addtion, the writer
task switches between asynchronous-normal and expedited grace-period
primitives driven by the same pair of module parameters.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit adds a object_debug option to rcutorture to allow the
debug-object-based checks for duplicate call_rcu() invocations to
be deterministically tested.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
[ paulmck: Banish mid-function ifdef, more or less per Josh Triplett. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Improve duplicate-callback test, per Lai Jiangshan. ]
When building the htmldocs (in verbose mode), scripts/kernel-doc reports the
following type of warnings:
Warning(kernel/workqueue.c:653): No description found for return value of
'get_work_pool'
Fix them by:
- Using "Return:" sections to introduce descriptions of return values
- Adding some missing descriptions
Signed-off-by: Yacine Belkadi <yacine.belkadi.1@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
For some strings (e.g. version string), they are permitted to be larger
than PAGE_SIZE (although meaningless), so recommend to use scnprintf()
instead of sprintf().
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
For some strings, they are permitted to be larger than PAGE_SIZE, so
need use scnprintf() instead of sprintf(), or it will cause issue.
One case is:
if a module version is crazy defined (length more than PAGE_SIZE),
'modinfo' command is still OK (print full contents),
but for "cat /sys/modules/'modname'/version", will cause issue in kernel.
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The ops that uses param_set_bool_enable_only() as its set function can
easily handle being used without an argument. There's no reason to
fail the loading of the module if it does not have one.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Currently the params.c code allows only two "set" functions to have
no arguments. If a parameter does not have an argument, then it
looks at the set function and tests if it is either param_set_bool()
or param_set_bint(). If it is not one of these functions, then it
fails the loading of the module.
But there may be module parameters that have different set functions
and still allow no arguments. But unless each of these cases adds
their function to the if statement, it wont be allowed to have no
arguments. This method gets rather messing and does not scale.
Instead, introduce a flags field to the kernel_param_ops, where if
the flag KERNEL_PARAM_FL_NOARG is set, the parameter will not fail
if it does not contain an argument. It will be expected that the
corresponding set function can handle a NULL pointer as "val".
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
In param_get_byte(), to which the macro STANDARD_PARAM_DEF(byte, ...) expands,
"%c" is used to print an unsigned char. So it gets printed as a character what
is not intended here. Use "%hhu" instead.
[Rusty: note drivers which would be effected:
drivers/net/wireless/cw1200/main.c
drivers/ntb/ntb_transport.c:68
drivers/scsi/lpfc/lpfc_attr.c
drivers/usb/atm/speedtch.c
drivers/usb/gadget/g_ffs.c
]
Acked-by: Jon Mason <jon.mason@intel.com> (for ntb)
Acked-by: Michal Nazarewicz <mina86@mina86.com> (for g_ffs.c)
Signed-off-by: Christoph Jaeger <christophjaeger@linux.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pull timer fixes from Ingo Molnar:
"Three small fixlets"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz: fix compile warning in tick_nohz_init()
nohz: Do not warn about unstable tsc unless user uses nohz_full
sched_clock: Fix integer overflow
Fix new kernel-doc warnings in kernel/wait.c:
Warning(kernel/wait.c:374): No description found for parameter 'p'
Warning(kernel/wait.c:374): Excess function parameter 'word' description in 'wake_up_atomic_t'
Warning(kernel/wait.c:374): Excess function parameter 'bit' description in 'wake_up_atomic_t'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
81eeaf0411 ("cgroup: make cftype->[un]register_event() deal with
cgroup_subsys_state inst ead of cgroup") updated the cftype event
methods to take @css (cgroup_subsys_state) instead of @cgroup;
however, it incorrectly used @css passed to
cgroup_write_event_control(), which the dummy_css for the cgroup as
the file is a cgroup core file. This leads to oops on event
registration.
Fix it by using the css matching the event target file. Note that
cgroup_write_event_control() now disallows cgroup core files from
being event sources. This is for simplicity and doesn't matter as
cgroup_event will be moved and made specific to memcg.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
105347ba5 ("cgroup: make cgroup_file_open() rcu_read_lock() around
cgroup_css() and add cfent->css") added cfent->css to cache the
associted cgroup_subsys_state across file operations.
A cfent is associated with single css throughout its lifetime and the
origimal commit initialized the cache pointer during cgroup_add_file()
and verified that it matches the actual one in cgroup_file_open().
While this works fine for !root cgroups, it's broken for root cgroups
as files in a root cgroup are created before the css's are associated
with the cgroup and thus cgroup_css() call in cgroup_add_file()
returns NULL associating all cfents in the root cgroup with NULL css.
This makes cgroup_file_open() trigger WARN and fail with -ENODEV for
all !core subsystem files in the root cgroups.
There's no reason to initialize cfent->css separately from
cgroup_add_file(). As the association never changes,
cgroup_file_open() can set it unconditionally every time and
containing the logic in cgroup_file_open() makes more sense anyway as
the only reason it's necessary is file->private_data being already
occupied.
Fix it by setting cfent->css unconditionally from cgroup_file_open().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Now we want cgroup core to always provide the css to use to the
subsystems, so change this API to css_from_id().
Uninline css_from_id(), because it's getting bigger and cgroup_css()
has been unexported.
While at it, remove the #ifdef, and shuffle the order of the args.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit adds an isidle and jiffies argument to force_qs_rnp(),
dyntick_save_progress_counter(), and rcu_implicit_dynticks_qs() to enable
RCU's force-quiescent-state process to check for full-system idle.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
[ paulmck: Use true and false for boolean constants per Lai Jiangshan. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit adds control variables and states for full-system idle.
The system will progress through the states in numerical order when
the system is fully idle (other than the timekeeping CPU), and reset
down to the initial state if any non-timekeeping CPU goes non-idle.
The current state is kept in full_sysidle_state.
One flavor of RCU will be in charge of driving the state machine,
defined by rcu_sysidle_state. This should be the busiest flavor of RCU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit adds the code that updates the rcu_dyntick structure's
new fields to track the per-CPU idle state based on interrupts and
transitions into and out of the idle loop (NMIs are ignored because NMI
handlers cannot cleanly read out the time anyway). This code is similar
to the code that maintains RCU's idea of per-CPU idleness, but differs
in that RCU treats CPUs running in user mode as idle, where this new
code does not.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit adds fields to the rcu_dyntick structure that are used to
detect idle CPUs. These new fields differ from the existing ones in
that the existing ones consider a CPU executing in user mode to be idle,
where the new ones consider CPUs executing in user mode to be busy.
The handling of these new fields is otherwise quite similar to that for
the exiting fields. This commit also adds the initialization required
for these fields.
So, why is usermode execution treated differently, with RCU considering
it a quiescent state equivalent to idle, while in contrast the new
full-system idle state detection considers usermode execution to be
non-idle?
It turns out that although one of RCU's quiescent states is usermode
execution, it is not a full-system idle state. This is because the
purpose of the full-system idle state is not RCU, but rather determining
when accurate timekeeping can safely be disabled. Whenever accurate
timekeeping is required in a CONFIG_NO_HZ_FULL kernel, at least one
CPU must keep the scheduling-clock tick going. If even one CPU is
executing in user mode, accurate timekeeping is requires, particularly for
architectures where gettimeofday() and friends do not enter the kernel.
Only when all CPUs are really and truly idle can accurate timekeeping be
disabled, allowing all CPUs to turn off the scheduling clock interrupt,
thus greatly improving energy efficiency.
This naturally raises the question "Why is this code in RCU rather than in
timekeeping?", and the answer is that RCU has the data and infrastructure
to efficiently make this determination.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
At least one CPU must keep the scheduling-clock tick running for
timekeeping purposes whenever there is a non-idle CPU. However, with
the new nohz_full adaptive-idle machinery, it is difficult to distinguish
between all CPUs really being idle as opposed to all non-idle CPUs being
in adaptive-ticks mode. This commit therefore adds a Kconfig parameter
as a first step towards enabling a scalable detection of full-system
idle state.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
[ paulmck: Update help text per Frederic Weisbecker. ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The rcu_user_enter_after_irq() and rcu_user_exit_after_irq()
functions were intended for use by adaptive ticks, but changes
in implementation have rendered them unnecessary. This commit
therefore removes them.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
When setting up an in-the-future "advanced" grace period, the code needs
to wake up the relevant grace-period kthread, which it currently does
unconditionally. However, this results in needless wakeups in the case
where the advanced grace period is being set up by the grace-period
kthread itself, which is a non-uncommon situation. This commit therefore
checks to see if the running thread is the grace-period kthread, and
avoids doing the irq_work_queue()-mediated wakeup in that case.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
If someone does a duplicate call_rcu(), the worst thing the second
call_rcu() could do would be to actually queue the callback the second
time because doing so corrupts whatever list the callback was already
queued on. This commit therefore makes __call_rcu() check the new
return value from debug-objects and leak the callback upon error.
This commit also substitutes rcu_leak_callback() for whatever callback
function was previously in place in order to avoid freeing the callback
out from under any readers that might still be referencing it.
These changes increase the probability that the debug-objects error
messages will actually make it somewhere visible.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The current debug-objects fixups are complex and heavyweight, and the
fixups are not complete: Even with the fixups, RCU's callback lists
can still be corrupted. This commit therefore strips the fixups down
to their minimal form, eliminating two of the three.
It would be even better if (for example) call_rcu() simply leaked
any problematic callbacks, but for that to happen, the debug-objects
system would need to inform its caller of suspicious situations.
This is the subject of a later commit in this series.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
CONFIG_RCU_FAST_NO_HZ can increase grace-period durations by up to
a factor of four, which can result in long suspend and resume times.
Thus, this commit temporarily switches to expedited grace periods when
suspending the box and return to normal settings when resuming. Similar
logic is applied to hibernation.
Because expedited grace periods are of dubious benefit on very large
systems, so this commit restricts their automated use during suspend
and resume to systems of 256 or fewer CPUs. (Some day a number of
Linux-kernel facilities, including RCU's expedited grace periods,
will be more scalable, but I need to see bug reports first.)
[ paulmck: This also papers over an audio/irq bug, but hopefully that will
be fixed soon. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Pull cgroup fix from Tejun Heo:
"This contains one patch to fix the return value of cpuset's cgroups
interface function, which used to always return -ENODEV for the writes
on the 'memory_pressure_enabled' file"
* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: fix the return value of cpuset_write_u64()
- The removal of delayed_work_pending() checks from kernel/power/qos.c
done in 3.9 introduced a deadlock in pm_qos_work_fn(). Fix from
Stephen Boyd.
/
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Merge tag 'pm-3.11-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fix from Rafael Wysocki:
"The removal of delayed_work_pending() checks from kernel/power/qos.c
done in 3.9 introduced a deadlock in pm_qos_work_fn().
Fix from Stephen Boyd"
* tag 'pm-3.11-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM / QoS: Fix workqueue deadlock when using pm_qos_update_request_timeout()
Freq events may not always be affine to a particular CPU. As such,
account_event_cpu() may crash if we account per cpu a freq event
that has event->cpu == -1.
To solve this, lets account freq events globally. In practice
this doesn't change much the picture because perf tools create
per-task perf events with one event per CPU by default. Profiling a
single CPU is usually a corner case so there is no much point in
optimizing things that way.
Reported-by: Jiri Olsa <jolsa@redhat.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375460996-16329-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When we fail to allocate the callchain buffers, we roll back the refcount
we did and return from get_callchain_buffers().
However we take the refcount and allocate under the callchain lock
but the rollback is done outside the lock.
As a result, while we roll back, some concurrent callchain user may
call get_callchain_buffers(), see the non-zero refcount and give up
because the buffers are NULL without itself retrying the allocation.
The consequences aren't that bad but that behaviour looks weird enough and
it's better to give their chances to the following callchain users where
we failed.
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375460996-16329-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
tick_nohz_full_kick_all() is useful to notify all full dynticks
CPUs that there is a system state change to checkout before
re-evaluating the need for the tick.
Unfortunately this is implemented using smp_call_function_many()
that ignores the local CPU. This CPU also needs to re-evaluate
the tick.
on_each_cpu_mask() is not useful either because we don't want to
re-evaluate the tick state in place but asynchronously from an IPI
to avoid messing up with any random locking scenario.
So lets call tick_nohz_full_kick() from tick_nohz_full_kick_all()
so that the usual irq work takes care of it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375460996-16329-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use of a this_cpu() operation reduces the number of instructions used
for accounting (account_user_time()) and frees up some registers. This is in
the scheduler tick hotpath.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/00000140596dd165-338ff7f5-893b-4fec-b251-aaac5557239e-000000@email.amazonses.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If doms_new is NULL, partition_sched_domains() will reset ndoms_cur
to 0, and free old sched domains with free_sched_domains(doms_cur, ndoms_cur).
As ndoms_cur is 0, the cpumask will not be freed.
Signed-off-by: Xiaotian Feng <xtfeng@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375790802-11857-1-git-send-email-xtfeng@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use inode_capable() to check if SUID|SGID bits should be cleared to match
similar check in inode_change_ok().
The check for CAP_LINUX_IMMUTABLE was not modified since all other file
systems also check against init_user_ns rather than current_user_ns.
Only allow changing of projid from init_user_ns.
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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Merge tag 'v3.11-rc5' into perf/core
Merge Linux 3.11-rc5, to sync up with the latest upstream fixes since -rc1.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge a bunch of fixes from Andrew Morton.
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
fs/proc/task_mmu.c: fix buffer overflow in add_page_map()
arch: *: Kconfig: add "kernel/Kconfig.freezer" to "arch/*/Kconfig"
ocfs2: fix null pointer dereference in ocfs2_dir_foreach_blk_id()
x86 get_unmapped_area(): use proper mmap base for bottom-up direction
ocfs2: fix NULL pointer dereference in ocfs2_duplicate_clusters_by_page
ocfs2: Revert 40bd62e to avoid regression in extended allocation
drivers/rtc/rtc-stmp3xxx.c: provide timeout for potentially endless loop polling a HW bit
hugetlb: fix lockdep splat caused by pmd sharing
aoe: adjust ref of head for compound page tails
microblaze: fix clone syscall
mm: save soft-dirty bits on file pages
mm: save soft-dirty bits on swapped pages
memcg: don't initialize kmem-cache destroying work for root caches
Pull nohz improvements from Frederic Weisbecker:
" It mostly contains fixes and full dynticks off-case optimizations. I believe that
distros want to enable this feature so it seems important to optimize the case
where the "nohz_full=" parameter is empty. ie: I'm trying to remove any performance
regression that comes with NO_HZ_FULL=y when the feature is not used.
This patchset improves the current situation a lot (off-case appears to be around 11% faster
with hackbench, although I guess it may vary depending on the configuration but it should be
significantly faster in any case) now there is still some work to do: I can still observe a
remaining loss of 1.6% throughput seen with hackbench compared to CONFIG_NO_HZ_FULL=n. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Scheduler IPIs and task context switches are serious fast path.
Let's try to hide as much as we can the impact of full
dynticks APIs' off case that are called on these sites
through the use of static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
These APIs are frequenctly accessed and priority is given
to optimize the full dynticks off-case in order to let
distros enable this feature without suffering from
significant performance regressions.
Let's inline these APIs and optimize them with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Rename the full dynticks's cpumask and cpumask state variables
to some more exportable names.
These will be used later from global headers to optimize
the main full dynticks APIs in conjunction with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
The vtime delta update performed by get_vtime_delta() always check
that the source of the snapshot is valid.
Meanhile the snapshot updaters that rely on get_vtime_delta() also
set the new snapshot origin. But some of them do this right before
the call to get_vtime_delta(), making its debug check useless.
This is easily fixable by moving the snapshot origin update after
the call to get_vtime_delta(). The order doesn't matter there.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
The cputime accounting in full dynticks can be a subtle
mixup of CPUs using tick based accounting and others using
generic vtime.
As long as the tick can have a share on producing these stats, we
want to scale the result against CFS precise accounting as the tick
can miss some task hiding between the periodic interrupt.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
If no CPU is in the full dynticks range, we can avoid the full
dynticks cputime accounting through generic vtime along with its
overhead and use the traditional tick based accounting instead.
Let's do this and nope the off case with static keys.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
get_vtime_delta() must be called under the task vtime_seqlock
with the code that does the cputime accounting flush.
Otherwise the cputime reader can be fooled and run into
a race where it sees the snapshot update but misses the
cputime flush. As a result it can report a cputime that is
way too short.
Fix vtime_account_user() that wasn't complying to that rule.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Some generic vtime APIs check if the vtime accounting
is enabled on the local CPU before doing their work.
Some of these are not needed because all their callers already
take care of that. Let's remove the checks on these.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
This can be useful to track all kernel/user round trips.
And it's also helpful to debug the context tracking subsystem.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
No need for syscall slowpath if no CPU is full dynticks,
rather nop this in this case.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Optimize guest entry/exit APIs with static keys. This minimize
the overhead for those who enable CONFIG_NO_HZ_FULL without
always using it. Having no range passed to nohz_full= should
result in the probes overhead to be minimized.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Optimize user and exception entry/exit APIs with static
keys. This minimize the overhead for those who enable
CONFIG_NO_HZ_FULL without always using it. Having no range
passed to nohz_full= should result in the probes to be nopped
(at least we hope so...).
If this proves not be enough in the long term, we'll need
to bring an exception slow path by re-routing the exception
handlers.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Prepare for using a static key in the context tracking subsystem.
This will help optimizing the off case on its many users:
* user_enter, user_exit, exception_enter, exception_exit, guest_enter,
guest_exit, vtime_*()
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Fix inadvertent breakage in the clone syscall ABI for Microblaze that
was introduced in commit f3268edbe6 ("microblaze: switch to generic
fork/vfork/clone").
The Microblaze syscall ABI for clone takes the parent tid address in the
4th argument; the third argument slot is used for the stack size. The
incorrectly-used CLONE_BACKWARDS type assigned parent tid to the 3rd
slot.
This commit restores the original ABI so that existing userspace libc
code will work correctly.
All kernel versions from v3.8-rc1 were affected.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the planned unified hierarchy, individual css's will be created
and destroyed dynamically across the lifetime of a cgroup. To enable
such usages, css destruction is being decoupled from cgroup
destruction. Most of the destruction path has been decoupled but the
actual free of css still depends on cgroup free path.
When all css refs are drained, css_release() kicks off
css_free_work_fn() which puts the cgroup. When the cgroup refcnt
reaches zero, cgroup_diput() is invoked which in turn schedules RCU
free of the cgroup. After a grace period, all css's are freed along
with the cgroup itself.
This patch moves the RCU grace period and css freeing from cgroup
release path to css release path. css_release(), instead of kicking
off css_free_work_fn() directly, schedules RCU callback
css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a
RCU grace period. css_free_work_fn() is updated to free the css
directly.
The five-way punting - percpu ref kill confirmation, a work item,
percpu ref release, RCU grace period, and again a work item - is quite
hairy but the work items are there only to provide process context and
the actual sequence is kill confirm -> release -> RCU free, which
isn't simple but not too crazy.
This removes cgroup_css() usage after offline_css() allowing clearing
cgroup->subsys[] from offline_css(), which makes it consistent with
online_css() and brings it closer to proper lifetime management for
individual css's.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
With the planned unified hierarchy, individual css's will be created
and destroyed dynamically across the lifetime of a cgroup. To enable
such usages, css destruction is being decoupled from cgroup
destruction. This patch moves subsys file removal from
cgroup_destroy_locked() to kill_css().
While this changes the order of destruction operations, the changes
shouldn't be noticeable to cgroup subsystems or userland.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Factor out css ref killing from cgroup_destroy_locked() into
kill_css(). We're gonna add more to the path and the factored out
function will eventually be called from other places too.
While at it, replace open coded percpu_ref_get() with css_get() for
consistency. This shouldn't cause any functional difference as the
function is not used for root cgroups.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Currently, css (cgroup_subsys_state) lifetime is tied to that of the
associated cgroup. css's are created when the associated cgroup is
created and destroyed when it gets destroyed. Also, individual css's
aren't RCU protected but the whole cgroup is. With the planned
unified hierarchy, css's will need to be dynamically created and
destroyed within the lifetime of a cgroup.
To enable such usages, this patch decouples css destruction from
cgroup destruction - offline_css() invocation and the final css_put()
are moved from cgroup_destroy_css_killed() to css_killed_work_fn().
Now each css is individually offlined and put as its reference count
is killed instead of waiting for all css's attached to the cgroup to
finish refcnt killing and then proceeding to offlining and putting
them together.
While this changes the order of destruction operations, the changes
shouldn't be noticeable to cgroup subsystems or userland.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Currently, css (cgroup_subsys_state) lifetime is tied to that of the
associated cgroup. With the planned unified hierarchy, css's will be
dynamically created and destroyed within the lifetime of a cgroup. To
enable such usages, css's will be individually RCU protected instead
of being tied to the cgroup.
cgroup->css_kill_cnt is used during cgroup destruction to wait for css
reference count disable; however, this model doesn't work once css's
lifetimes are managed separately from cgroup's. This patch replaces
it with cgroup->nr_css which is an cgroup_mutex protected integer
counting the number of attached css's. The count is incremented from
online_css() and decremented after refcnt kill is confirmed. If the
count reaches zero and the cgroup is marked dead, the second stage of
cgroup destruction is kicked off. If a cgroup doesn't have any css
attached at the time of rmdir, cgroup_destroy_locked() now invokes the
second stage directly as no css kill confirmation would happen.
cgroup_offline_fn() - the second step of cgroup destruction - is
renamed to cgroup_destroy_css_killed() and now expects to be called
with cgroup_mutex held.
While this patch changes how css destruction is punted to work items,
it shouldn't change any visible behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
css (cgroup_subsys_state) offlining, which requires process context,
will be moved to ref kill confirmation. In preparation, bounce
css_killed handling through css->destroy_work.
css_ref_killed_fn() is renamed to css_killed_ref_fn() so that it's
consistent with the new css_killed_work_fn().
This patch adds an additional work item bouncing but doesn't change
the actual logic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Currently, css (cgroup_subsys_state) lifetime is tied to that of the
associated cgroup. With the planned unified hierarchy, css's will be
dynamically created and destroyed within the lifetime of a cgroup. To
enable such usages, css's will be individually RCU protected instead
of being tied to the cgroup.
In preparation, this patch moves cgroup->subsys[] assignment from
init_css() to online_css(). As this means that a newly initialized
css should be remembered separately and that cgroup_css() returns NULL
between init and online, cgroup_create() is updated so that it stores
newly created css's in a local array css_ar[] and
cgroup_init/load_subsys() are updated to use local variable @css
instead of using cgroup_css(). This change also slightly simplifies
error path of cgroup_create().
While this patch changes when cgroup->subsys[] is initialized, this
change isn't visible to subsystems or userland.
v2: This patch wasn't updated accordingly after the previous "cgroup:
reorganize css init / exit paths" was updated leading to missing a
css_ar[] conversion in cgroup_create() and thus boot failure. Fix
it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Pull scheduler fixes from Ingo Molnar:
"Docbook fixes that make 99% of the diffstat, plus a oneliner fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Ensure update_cfs_shares() is called for parents of continuously-running tasks
sched: Fix some kernel-doc warnings
pm_qos_update_request_timeout() updates a qos and then schedules
a delayed work item to bring the qos back down to the default
after the timeout. When the work item runs, pm_qos_work_fn() will
call pm_qos_update_request() and deadlock because it tries to
cancel itself via cancel_delayed_work_sync(). Future callers of
that qos will also hang waiting to cancel the work that is
canceling itself. Let's extract the little bit of code that does
the real work of pm_qos_update_request() and call it from the
work function so that we don't deadlock.
Before ed1ac6e (PM: don't use [delayed_]work_pending()) this didn't
happen because the work function wouldn't try to cancel itself.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: 3.9+ <stable@vger.kernel.org> # 3.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This is only theoretical, but after try_to_wake_up(p) was changed
to check p->state under p->pi_lock the code like
__set_current_state(TASK_INTERRUPTIBLE);
schedule();
can miss a signal. This is the special case of wait-for-condition,
it relies on try_to_wake_up/schedule interaction and thus it does
not need mb() between __set_current_state() and if(signal_pending).
However, this __set_current_state() can move into the critical
section protected by rq->lock, now that try_to_wake_up() takes
another lock we need to ensure that it can't be reordered with
"if (signal_pending(current))" check inside that section.
The patch is actually one-liner, it simply adds smp_wmb() before
spin_lock_irq(rq->lock). This is what try_to_wake_up() already
does by the same reason.
We turn this wmb() into the new helper, smp_mb__before_spinlock(),
for better documentation and to allow the architectures to change
the default implementation.
While at it, kill smp_mb__after_lock(), it has no callers.
Perhaps we can also add smp_mb__before/after_spinunlock() for
prepare_to_wait().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
css (cgroup_subsys_state) lifetime management is about to be
restructured. In prepartion, make the following mostly trivial
changes.
* init_cgroup_css() is renamed to init_css() so that it's consistent
with other css handling functions.
* alloc_css_id(), online_css() and offline_css() updated to take @css
instead of cgroups and subsys IDs.
This patch doesn't make any functional changes.
v2: v1 merged two for_each_root_subsys() loops in cgroup_create() but
Li Zefan pointed out that it breaks error path. Dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
For the planned unified hierarchy, each css (cgroup_subsys_state) will
be RCU protected so that it can be created and destroyed individually
while allowing RCU accesses. Previous changes ensured that all
cgroup->subsys[] accesses use the cgroup_css() accessor. This patch
adds __rcu modifier to cgroup->subsys[], add matching RCU dereference
in cgroup_css() and convert all assignments to either
rcu_assign_pointer() or RCU_INIT_POINTER().
This change prepares for the actual RCUfication of css's and doesn't
introduce any visible behavior change. The conversion is verified
with sparse and all accesses are properly RCU annotated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
For the planned unified hierarchy, each css (cgroup_subsys_state) will
be RCU protected so that it can be created and destroyed individually
while allowing RCU accesses, and cgroup_css() will soon require either
holding cgroup_mutex or RCU read lock.
This patch updates cgroup_file_open() such that it acquires the
associated css under rcu_read_lock(). While cgroup_file_css() usages
in other file operations are safe due to the reference from open,
cgroup_css() wouldn't know that and will still trigger warnings. It'd
be cleanest to store the acquired css in file->prvidate_data for
further file operations but that's already used by seqfile. This
patch instead adds cfent->css to cache the associated css. Note that
while this field is initialized during cfe init, it should only be
considered valid while the file is open.
This patch doesn't change visible behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup->subsys[] will become RCU protected and thus all cgroup_css()
usages should either be under RCU read lock or cgroup_mutex. This
patch updates cgroup_css_from_dir() which returns the matching
cgroup_subsys_state given a directory file and subsys_id so that it
requires RCU read lock and updates its sole user
perf_cgroup_connect().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
With the planned unified hierarchy, css's (cgroup_subsys_state) will
be RCU protected and allowed to be attached and detached dynamically
over the course of a cgroup's lifetime. This means that css's will
stay accessible after being detached from its cgroup - the matching
pointer in cgroup->subsys[] cleared - for ref draining and RCU grace
period.
cgroup core still wants to guarantee that the parent css is never
destroyed before its children and css_parent() always returns the
parent regardless of the state of the child css as long as it's
accessible.
This patch makes css's hold onto their parents and adds css->parent so
that the parent css is never detroyed before its children and can be
determined without consulting the cgroups.
cgroup->dummy_css is also updated to point to the parent dummy_css;
however, it doesn't need to worry about object lifetime as the parent
cgroup is already pinned by the child.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
css (cgroup_subsys_state) will become RCU protected and there will be
two stages which require punting to work item during release. To
prepare for using the work item for multiple times, rename
css->dput_work to css->destroy_work and css_dput_fn() to
css_free_work_fn() and move work item initialization from css init to
right before the actual usage.
This reorganization doesn't introduce any behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_css() is the accessor for cgroup->subsys[] but is not used
consistently. cgroup->subsys[] will become RCU protected and
cgroup_css() will grow synchronization sanity checks. In preparation,
make all cgroup->subsys[] dereferences use cgroup_css() consistently.
This patch doesn't introduce any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
CPU system maps are protected with reader/writer locks. The reader
lock, get_online_cpus(), assures that the maps are not updated while
holding the lock. The writer lock, cpu_hotplug_begin(), is used to
udpate the cpu maps along with cpu_maps_update_begin().
However, the ACPI processor handler updates the cpu maps without
holding the the writer lock.
acpi_map_lsapic() is called from acpi_processor_hotadd_init() to
update cpu_possible_mask and cpu_present_mask. acpi_unmap_lsapic()
is called from acpi_processor_remove() to update cpu_possible_mask.
Currently, they are either unprotected or protected with the reader
lock, which is not correct.
For example, the get_online_cpus() below is supposed to assure that
cpu_possible_mask is not changed while the code is iterating with
for_each_possible_cpu().
get_online_cpus();
for_each_possible_cpu(cpu) {
:
}
put_online_cpus();
However, this lock has no protection with CPU hotplug since the ACPI
processor handler does not use the writer lock when it updates
cpu_possible_mask. The reader lock does not serialize within the
readers.
This patch protects them with the writer lock with cpu_hotplug_begin()
along with cpu_maps_update_begin(), which must be held before calling
cpu_hotplug_begin(). It also protects arch_register_cpu() /
arch_unregister_cpu(), which creates / deletes a sysfs cpu device
interface. For this purpose it changes cpu_hotplug_begin() and
cpu_hotplug_done() to global and exports them in cpu.h.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Now that the full dynticks subsystem only enables the context tracking
on full dynticks CPUs, lets remove the dependency on CONTEXT_TRACKING_FORCE
This dependency was a hack to enable the context tracking widely for the
full dynticks susbsystem until the latter becomes able to enable it in a
more CPU-finegrained fashion.
Now CONTEXT_TRACKING_FORCE only stands for testing on archs that
work on support for the context tracking while full dynticks can't be
used yet due to unmet dependencies. It simulates a system where all CPUs
are full dynticks so that RCU user extended quiescent states and dynticks
cputime accounting can be tested on the given arch.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
The context tracking subsystem has the ability to selectively
enable the tracking on any defined subset of CPU. This means that
we can define a CPU range that doesn't run the context tracking
and another range that does.
Now what we want in practice is to enable the tracking on full
dynticks CPUs only. In order to perform this, we just need to pass
our full dynticks CPU range selection from the full dynticks
subsystem to the context tracking.
This way we can spare the overhead of RCU user extended quiescent
state and vtime maintainance on the CPUs that are outside the
full dynticks range. Just keep in mind the raw context tracking
itself is still necessary everywhere.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
As long as the context tracking is enabled on any CPU, even
a single one, all other CPUs need to keep track of their
user <-> kernel boundaries cross as well.
This is because a task can sleep while servicing an exception
that happened in the kernel or in userspace. Then when the task
eventually wakes up and return from the exception, the CPU needs
to know if we resume in userspace or in the kernel. exception_exit()
get this information from exception_enter() that saved the previous
state.
If the CPU where the exception happened didn't keep track of
these informations, exception_exit() doesn't know which state
tracking to restore on the CPU where the task got migrated
and we may return to userspace with the context tracking
subsystem thinking that we are in kernel mode.
This can be fixed in the long term if we move our context tracking
probes on very low level arch fast path user <-> kernel boundary,
although even that is worrisome as an exception can still happen
in the few instructions between the probe and the actual iret.
Also we are not yet ready to set these probes in the fast path given
the potential overhead problem it induces.
So let's fix this by always enable context tracking even on CPUs
that are not in the full dynticks range. OTOH we can spare the
rcu_user_*() and vtime_user_*() calls there because the tick runs
on these CPUs and we can handle RCU state machine and cputime
accounting through it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Update a stale comment from the old vtime era and document some
locking that might be non obvious.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
1) If context tracking is enabled with native vtime accounting (which
combo is useless except for dev testing), we call vtime_guest_enter()
and vtime_guest_exit() on host <-> guest switches. But those are stubs
in this configurations. As a result, cputime is not correctly flushed
on kvm context switches.
2) If context tracking runs but is disabled on some CPUs, those
CPUs end up calling __guest_enter/__guest_exit which in turn
call vtime_account_system(). We don't want to call this because we
run in tick based accounting for these CPUs.
Refactor the guest_enter/guest_exit code such that all combinations
finally work.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
preempt_schedule() and preempt_schedule_context() open
code their preemptability checks.
Use the standard API instead for consolidation.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Pull w/w mutex deadlock injection fix from Ingo Molnar.
This bug made the CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y option largely
useless, but wouldn't affect normal users.
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mutex: Fix w/w mutex deadlock injection
Commit b202952075 ("perf, core: Rate limit
perf_sched_events jump_label patching") introduced rate limiting
for jump label disabling. The changes were made in the jump label code
in order to be more widely available and to keep things tidier. This is
all fine, except now jump_label.h includes linux/workqueue.h, which
makes it impossible to include jump_label.h from anything that
workqueue.h needs. For example, it's now impossible to include
jump_label.h from asm/spinlock.h, which is done in proposed
pv-ticketlock patches. This patch splits out the rate limiting related
changes from jump_label.h into a new file, jump_label_ratelimit.h, to
resolve the issue.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Link: http://lkml.kernel.org/r/1376058122-8248-10-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Previously, all css descendant iterators didn't include the origin
(root of subtree) css in the iteration. The reasons were maintaining
consistency with css_for_each_child() and that at the time of
introduction more use cases needed skipping the origin anyway;
however, given that css_is_descendant() considers self to be a
descendant, omitting the origin css has become more confusing and
looking at the accumulated use cases rather clearly indicates that
including origin would result in simpler code overall.
While this is a change which can easily lead to subtle bugs, cgroup
API including the iterators has recently gone through major
restructuring and no out-of-tree changes will be applicable without
adjustments making this a relatively acceptable opportunity for this
type of change.
The conversions are mostly straight-forward. If the iteration block
had explicit origin handling before or after, it's moved inside the
iteration. If not, if (pos == origin) continue; is added. Some
conversions add extra reference get/put around origin handling by
consolidating origin handling and the rest. While the extra ref
operations aren't strictly necessary, this shouldn't cause any
noticeable difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
cgroup_css() no longer has any user left outside cgroup.c proper and
we don't want subsystems to grow new usages of the function. cgroup
core should always provide the css to use to the subsystems, which
will make dynamic creation and destruction of css's across the
lifetime of a cgroup much more manageable than exposing the cgroup
directly to subsystems and let them dereference css's from it.
Make cgroup_css() a static function in cgroup.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle. This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.
cgroup_taskset which is used by the subsystem attach methods is the
last cgroup subsystem API which isn't using css as the handle. Update
cgroup_taskset_cur_cgroup() to cgroup_taskset_cur_css() and
cgroup_taskset_for_each() to take @skip_css instead of @skip_cgrp.
The conversions are pretty mechanical. One exception is
cpuset::cgroup_cs(), which lost its last user and got removed.
This patch shouldn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle. This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.
cftype->[un]register_event() is among the remaining couple interfaces
which still use struct cgroup. Convert it to cgroup_subsys_state.
The conversion is mostly mechanical and removes the last users of
mem_cgroup_from_cont() and cg_to_vmpressure(), which are removed.
v2: indentation update as suggested by Li Zefan.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle. This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.
This patch converts task iterators to deal with css instead of cgroup.
Note that under unified hierarchy, different sets of tasks will be
considered belonging to a given cgroup depending on the subsystem in
question and making the iterators deal with css instead cgroup
provides them with enough information about the iteration.
While at it, fix several function comment formats in cpuset.c.
This patch doesn't introduce any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
cgroup_scan_tasks() takes a pointer to struct cgroup_scanner as its
sole argument and the only function of that struct is packing the
arguments of the function call which are consisted of five fields.
It's not too unusual to pack parameters into a struct when the number
of arguments gets excessive or the whole set needs to be passed around
a lot, but neither holds here making it just weird.
Drop struct cgroup_scanner and pass the params directly to
cgroup_scan_tasks(). Note that struct cpuset_change_nodemask_arg was
added to cpuset.c to pass both ->cs and ->newmems pointer to
cpuset_change_nodemask() using single data pointer.
This doesn't make any functional differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Currently all cgroup_task_iter functions require @cgrp to be passed
in, which is superflous and increases chance of usage error. Make
cgroup_task_iter remember the cgroup being iterated and drop @cgrp
argument from next and end functions.
This patch doesn't introduce any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
cgroup now has multiple iterators and it's quite confusing to have
something which walks over tasks of a single cgroup named cgroup_iter.
Let's rename it to cgroup_task_iter.
While at it, reformat / update comments and replace the overview
comment above the interface function decls with proper function
comments. Such overview can be useful but function comments should be
more than enough here.
This is pure rename and doesn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
For some reason, cgroup_advance_iter() is standing lonely all away
from its iter comrades. Relocate it.
This is cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup is currently in the process of transitioning to using css
(cgroup_subsys_state) as the primary handle instead of cgroup in
subsystem API. For hierarchy iterators, this is beneficial because
* In most cases, css is the only thing subsystems care about anyway.
* On the planned unified hierarchy, iterations for different
subsystems will need to skip over different subtrees of the
hierarchy depending on which subsystems are enabled on each cgroup.
Passing around css makes it unnecessary to explicitly specify the
subsystem in question as css is intersection between cgroup and
subsystem
* For the planned unified hierarchy, css's would need to be created
and destroyed dynamically independent from cgroup hierarchy. Having
cgroup core manage css iteration makes enforcing deref rules a lot
easier.
Most subsystem conversions are straight-forward. Noteworthy changes
are
* blkio: cgroup_to_blkcg() is no longer used. Removed.
* freezer: cgroup_freezer() is no longer used. Removed.
* devices: cgroup_to_devcgroup() is no longer used. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
There are several places where the children list is accessed directly.
This patch converts those places to use cgroup_next_child(). This
will help updating the hierarchy iterators to use @css instead of
@cgrp.
While cgroup_next_child() can be heavy in pathological cases - e.g. a
lot of dead children, this shouldn't cause any noticeable behavior
differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup is transitioning to using css (cgroup_subsys_state) as the main
subsys interface handle instead of cgroup and the iterators will be
updated to use css too. The iterators need to walk the cgroup
hierarchy and return the css's matching the origin css, which is a bit
cumbersome to open code.
This patch converts cgroup_next_sibling() to cgroup_next_child() so
that it can handle all steps of direct child iteration. This will be
used to update iterators to take @css instead of @cgrp. In addition
to the new iteration init handling, cgroup_next_child() is
restructured so that the different branches share the end of iteration
condition check.
This patch doesn't change any behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.
This patch converts all cftype file operations to take @css instead of
@cgroup. cftypes for the cgroup core files don't have their subsytem
pointer set. These will automatically use the dummy_css added by the
previous patch and can be converted the same way.
Most subsystem conversions are straight forwards but there are some
interesting ones.
* freezer: update_if_frozen() is also converted to take @css instead
of @cgroup for consistency. This will make the code look simpler
too once iterators are converted to use css.
* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
vmpressure while mem_cgroup_from_cont() can be made static.
Updated accordingly.
* cpu: cgroup_tg() doesn't have any user left. Removed.
* cpuacct: cgroup_ca() doesn't have any user left. Removed.
* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
Removed.
* net_cls: cgrp_cls_state() doesn't have any user left. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>
cgroup subsystem API is being converted to use css
(cgroup_subsys_state) as the main handle, which makes things a bit
awkward for subsystem agnostic core features - the "cgroup.*"
interface files and various iterations - a bit awkward as they don't
have a css to use.
This patch adds cgroup->dummy_css which has NULL ->ss and whose only
role is pointing back to the cgroup. This will be used to support
subsystem agnostic features on the coming css based API.
css_parent() is updated to handle dummy_css's. Note that css will
soon grow its own ->parent field and css_parent() will be made
trivial.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Previously, each file read/write operation relied on the inode
reference count pinning the cgroup and simply checked whether the
cgroup was marked dead before proceeding to invoke the per-subsystem
callback. This was rather silly as it didn't have any synchronization
or css pinning around the check and the cgroup may be removed and all
css refs drained between the DEAD check and actual method invocation.
This patch pins the css between open() and release() so that it is
guaranteed to be alive for all file operations and remove the silly
DEAD checks from cgroup_file_read/write().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup is transitioning to using css (cgroup_subsys_state) instead of
cgroup as the primary subsystem handle. The cgroupfs file interface
will be converted to use css's which requires finding out the
subsystem from cftype so that the matching css can be determined from
the cgroup.
This patch adds cftype->ss which points to the subsystem the file
belongs to. The field is initialized while a cftype is being
registered. This makes it unnecessary to explicitly specify the
subsystem for other cftype handling functions. @ss argument dropped
from various cftype handling functions.
This patch shouldn't introduce any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup *
in subsystem implementations for the following reasons.
* With unified hierarchy, subsystems will be dynamically bound and
unbound from cgroups and thus css's (cgroup_subsys_state) may be
created and destroyed dynamically over the lifetime of a cgroup,
which is different from the current state where all css's are
allocated and destroyed together with the associated cgroup. This
in turn means that cgroup_css() should be synchronized and may
return NULL, making it more cumbersome to use.
* Differing levels of per-subsystem granularity in the unified
hierarchy means that the task and descendant iterators should behave
differently depending on the specific subsystem the iteration is
being performed for.
* In majority of the cases, subsystems only care about its part in the
cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods
often obtain the matching css pointer from the cgroup and don't
bother with the cgroup pointer itself. Passing around css fits
much better.
This patch converts all cgroup_subsys methods to take @css instead of
@cgroup. The conversions are mostly straight-forward. A few
noteworthy changes are
* ->css_alloc() now takes css of the parent cgroup rather than the
pointer to the new cgroup as the css for the new cgroup doesn't
exist yet. Knowing the parent css is enough for all the existing
subsystems.
* In kernel/cgroup.c::offline_css(), unnecessary open coded css
dereference is replaced with local variable access.
This patch shouldn't cause any behavior differences.
v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced
with local variable @css as suggested by Li Zefan.
Rebased on top of new for-3.12 which includes for-3.11-fixes so
that ->css_free() invocation added by da0a12caff ("cgroup: fix a
leak when percpu_ref_init() fails") is converted too. Suggested
by Li Zefan.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Currently, controllers have to explicitly follow the cgroup hierarchy
to find the parent of a given css. cgroup is moving towards using
cgroup_subsys_state as the main controller interface construct, so
let's provide a way to climb the hierarchy using just csses.
This patch implements css_parent() which, given a css, returns its
parent. The function is guarnateed to valid non-NULL parent css as
long as the target css is not at the top of the hierarchy.
freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices
are converted to use css_parent() instead of accessing cgroup->parent
directly.
* __parent_ca() is dropped from cpuacct and its usage is replaced with
parent_ca(). The only difference between the two was NULL test on
cgroup->parent which is now embedded in css_parent() making the
distinction moot. Note that eventually a css->parent field will be
added to css and the NULL check in css_parent() will go away.
This patch shouldn't cause any behavior differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
css (cgroup_subsys_state) is usually embedded in a subsys specific
data structure. Subsystems either use container_of() directly to cast
from css to such data structure or has an accessor function wrapping
such cast. As cgroup as whole is moving towards using css as the main
interface handle, add and update such accessors to ease dealing with
css's.
All accessors explicitly handle NULL input and return NULL in those
cases. While this looks like an extra branch in the code, as all
controllers specific data structures have css as the first field, the
casting doesn't involve any offsetting and the compiler can trivially
optimize out the branch.
* blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such
accessor. Added.
* memory, hugetlb and devices already had one but didn't explicitly
handle NULL input. Updated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
