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In the beginning of build_sched_groups() we called sched_domain_span() and
cached its return value in span. Few statements later we are calling it again to
get the same pointer.
Lets use the cached value instead as it hasn't changed in between.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/834ecd507071ad88aff039352dbc7e063dd996a7.1370948150.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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For loop for traversing sched_domain_topology was used at multiple placed in
core.c. This patch removes code redundancy by creating for_each_sd_topology().
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/e0e04542f54e9464bd9da54f5ccfe62ec6c4c0bc.1370861520.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Memory for sd is allocated with kzalloc_node() which will initialize its fields
with zero. In build_sched_domain() we are setting sd->child to child even if
child is NULL, which isn't required.
Lets do it only if child isn't NULL.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/f4753a1730051341003ad2ad29a3229c7356678e.1370861520.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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alloc_state will be overwritten by __visit_domain_allocation_hell() and so we
don't actually need to initialize alloc_state.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/df57734a075cc5ad130e1ae498702e24f2529ab8.1370861520.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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We are saving first scheduling domain for a cpu in build_sched_domains() by
iterating over the nested sd->child list. We don't actually need to do it this
way.
tl will be equal to sched_domain_topology for the first iteration and so we can
set *per_cpu_ptr(d.sd, i) based on that. So, save pointer to first SD while
running the iteration loop over tl's.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/fc473527cbc4dfa0b8eeef2a59db74684eb59a83.1370436120.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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build_sched_domain() never uses parameter struct s_data *d and so passing it is
useless.
Remove it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/545e0b4536166a15b4475abcafe5ed0db4ad4a2c.1370436120.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Most of the stuff from kernel/sched.c was moved to kernel/sched/core.c long time
back and the comments/Documentation never got updated.
I figured it out when I was going through sched-domains.txt and so thought of
fixing it globally.
I haven't crossed check if the stuff that is referenced in sched/core.c by all
these files is still present and hasn't changed as that wasn't the motive behind
this patch.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/cdff76a265326ab8d71922a1db5be599f20aad45.1370329560.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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default_cfs_period(), do_sched_cfs_period_timer(), do_sched_cfs_slack_timer()
already defined previously, no need to declare again.
Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/51AD8808.7020608@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Directly use rq to save some code.
Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/51AD87EB.1070605@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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[ Peter, this is based off of some of my work, I ran it though a few
tests and it passed. I also reviewed it, and added my SOB as I am
somewhat a co-author to it. ]
Based on the patch by Steven Rostedt from previous year:
https://lkml.org/lkml/2012/4/18/517
1)Simplify pull_rt_task() logic: search in pushable tasks of dest runqueue.
The only pullable tasks are the tasks which are pushable in their local rq,
and no others.
2)Remove .leaf_rt_rq_list member of struct rt_rq and functions connected
with it: nobody uses it since now.
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/287571370557898@web7d.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge in fixes before applying ongoing new work.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Dave Jones hit the following bug report:
===============================
[ INFO: suspicious RCU usage. ]
3.10.0-rc2+ #1 Not tainted
-------------------------------
include/linux/rcupdate.h:771 rcu_read_lock() used illegally while idle!
other info that might help us debug this:
RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
2 locks held by cc1/63645:
#0: (&rq->lock){-.-.-.}, at: [<ffffffff816b39fd>] __schedule+0xed/0x9b0
#1: (rcu_read_lock){.+.+..}, at: [<ffffffff8109d645>] cpuacct_charge+0x5/0x1f0
CPU: 1 PID: 63645 Comm: cc1 Not tainted 3.10.0-rc2+ #1 [loadavg: 40.57 27.55 13.39 25/277 64369]
Hardware name: Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
0000000000000000 ffff88010f78fcf8 ffffffff816ae383 ffff88010f78fd28
ffffffff810b698d ffff88011c092548 000000000023d073 ffff88011c092500
0000000000000001 ffff88010f78fd60 ffffffff8109d7c5 ffffffff8109d645
Call Trace:
[<ffffffff816ae383>] dump_stack+0x19/0x1b
[<ffffffff810b698d>] lockdep_rcu_suspicious+0xfd/0x130
[<ffffffff8109d7c5>] cpuacct_charge+0x185/0x1f0
[<ffffffff8109d645>] ? cpuacct_charge+0x5/0x1f0
[<ffffffff8108dffc>] update_curr+0xec/0x240
[<ffffffff8108f528>] put_prev_task_fair+0x228/0x480
[<ffffffff816b3a71>] __schedule+0x161/0x9b0
[<ffffffff816b4721>] preempt_schedule+0x51/0x80
[<ffffffff816b4800>] ? __cond_resched_softirq+0x60/0x60
[<ffffffff816b6824>] ? retint_careful+0x12/0x2e
[<ffffffff810ff3cc>] ftrace_ops_control_func+0x1dc/0x210
[<ffffffff816be280>] ftrace_call+0x5/0x2f
[<ffffffff816b681d>] ? retint_careful+0xb/0x2e
[<ffffffff816b4805>] ? schedule_user+0x5/0x70
[<ffffffff816b4805>] ? schedule_user+0x5/0x70
[<ffffffff816b6824>] ? retint_careful+0x12/0x2e
------------[ cut here ]------------
What happened was that the function tracer traced the schedule_user() code
that tells RCU that the system is coming back from userspace, and to
add the CPU back to the RCU monitoring.
Because the function tracer does a preempt_disable/enable_notrace() calls
the preempt_enable_notrace() checks the NEED_RESCHED flag. If it is set,
then preempt_schedule() is called. But this is called before the user_exit()
function can inform the kernel that the CPU is no longer in user mode and
needs to be accounted for by RCU.
The fix is to create a new preempt_schedule_context() that checks if
the kernel is still in user mode and if so to switch it to kernel mode
before calling schedule. It also switches back to user mode coming back
from schedule in need be.
The only user of this currently is the preempt_enable_notrace(), which is
only used by the tracing subsystem.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1369423420.6828.226.camel@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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I have faced a sequence where the Idle Load Balance was sometime not
triggered for a while on my platform, in the following scenario:
CPU 0 and CPU 1 are running tasks and CPU 2 is idle
CPU 1 kicks the Idle Load Balance
CPU 1 selects CPU 2 as the new Idle Load Balancer
CPU 2 sets NOHZ_BALANCE_KICK for CPU 2
CPU 2 sends a reschedule IPI to CPU 2
While CPU 3 wakes up, CPU 0 or CPU 1 migrates a waking up task A on CPU 2
CPU 2 finally wakes up, runs task A and discards the Idle Load Balance
task A quickly goes back to sleep (before a tick occurs on CPU 2)
CPU 2 goes back to idle with NOHZ_BALANCE_KICK set
Whenever CPU 2 will be selected as the ILB, no reschedule IPI will be sent
because NOHZ_BALANCE_KICK is already set and no Idle Load Balance will be
performed.
We must wait for the sched softirq to be raised on CPU 2 thanks to another
part the kernel to come back to clear NOHZ_BALANCE_KICK.
The proposed solution clears NOHZ_BALANCE_KICK in schedule_ipi if
we can't raise the sched_softirq for the Idle Load Balance.
Change since V1:
- move the clear of NOHZ_BALANCE_KICK in got_nohz_idle_kick if the ILB
can't run on this CPU (as suggested by Peter)
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1370419991-13870-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This allows us to use pdev->name for registering a PMU device.
IMO the name is not supposed to be changed anyway.
Signed-off-by: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1370339148-5566-1-git-send-email-mjonker@synopsys.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit 2b923c8 perf/x86: Check branch sampling priv level in generic code
was missing the check for the hypervisor (HV) priv level, so add it back.
With this patch, we get the following correct behavior:
# echo 2 >/proc/sys/kernel/perf_event_paranoid
$ perf record -j any,k noploop 1
Error:
You may not have permission to collect stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid:
-1 - Not paranoid at all
0 - Disallow raw tracepoint access for unpriv
1 - Disallow cpu events for unpriv
2 - Disallow kernel profiling for unpriv
$ perf record -j any,hv noploop 1
Error:
You may not have permission to collect stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid:
-1 - Not paranoid at all
0 - Disallow raw tracepoint access for unpriv
1 - Disallow cpu events for unpriv
2 - Disallow kernel profiling for unpriv
Signed-off-by: Stephane Eranian <eranian@google.com>
Acked-by: Petr Matousek <pmatouse@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130606090204.GA3725@quad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge in the latest fixes, to avoid conflicts with ongoing work.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Vince's fuzzer once again found holes. This time it spotted a leak in
the locked page accounting.
When an event had redirected output and its close() was the last
reference to the buffer we didn't have a vm context to undo accounting.
Change the code to destroy the buffer on the last munmap() and detach
all redirected events at that time. This provides us the right context
to undo the vm accounting.
Reported-and-tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130604084421.GI8923@twins.programming.kicks-ass.net
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Cont is short for container. control group was named process container
at first, but then people found container already has a meaning in
linux kernel.
Clean up the leftover variable name @cont.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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cgroup_serial_nr_cursor was created atomic64_t because I thought it
was never gonna used for anything other than assigning unique numbers
to cgroups and didn't want to worry about synchronization; however,
now we're using it as an event-stamp to distinguish cgroups created
before and after certain point which assumes that it's protected by
cgroup_mutex.
Let's make it clear by making it a u64. Also, rename it to
cgroup_serial_nr_next and make it point to the next nr to allocate so
that where it's pointing to is clear and more conventional.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
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We used root->allcg_list to iterate cgroup hierarchy because at that time
cgroup_for_each_descendant_pre() hasn't been invented.
tj: In cgroup_cfts_commit(), s/@serial_nr/@update_upto/, move the
assignment right above releasing cgroup_mutex and explain what's
going on there.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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The next patch will use it to determine if a cgroup is newly created
while we're iterating the cgroup hierarchy.
tj: Rephrased the comment on top of cgroup_serial_nr_cursor.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Joshua reported: Commit cd7b304dfaf1 (x86, range: fix missing merge
during add range) broke mtrr cleanup on his setup in 3.9.5.
corresponding commit in upstream is fbe06b7bae7c.
The reason is add_range_with_merge could generate blank spot.
We could avoid that by searching new expanded start/end, that
new range should include all connected ranges in range array.
At last add the new expanded start/end to the range array.
Also move up left array so do not add new blank slot in the
range array.
-v2: move left array to avoid enhance add_range()
-v3: include fix from Joshua about memmove declaring when
DYN_DEBUG is used.
Reported-by: Joshua Covington <joshuacov@googlemail.com>
Tested-by: Joshua Covington <joshuacov@googlemail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1371154622-8929-3-git-send-email-yinghai@kernel.org
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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The memory allocated in cgroup_add_cftypes() should be freed. The
effect of this bug is we leak a bit memory everytime we unload
cfq-iosched module if blkio cgroup is enabled.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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commit 5db9a4d99b0157a513944e9a44d29c9cec2e91dc
Author: Tejun Heo <tj@kernel.org>
Date: Sat Jul 7 16:08:18 2012 -0700
cgroup: fix cgroup hierarchy umount race
This commit fixed a race caused by the dput() in css_dput_fn(), but
the dput() in cgroup_event_remove() can also lead to the same BUG().
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
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cgroup_cfts_commit() uses dget() to keep cgroup alive after cgroup_mutex
is dropped, but dget() won't prevent cgroupfs from being umounted. When
the race happens, vfs will see some dentries with non-zero refcnt while
umount is in process.
Keep running this:
mount -t cgroup -o blkio xxx /cgroup
umount /cgroup
And this:
modprobe cfq-iosched
rmmod cfs-iosched
After a while, the BUG() in shrink_dcache_for_umount_subtree() may
be triggered:
BUG: Dentry xxx{i=0,n=blkio.yyy} still in use (1) [umount of cgroup cgroup]
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
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cgroup's rename(2) isn't a proper migration implementation - it can't
move the cgroup to a different parent in the hierarchy. All it can do
is swapping the name string for that cgroup. This isn't useful and
can mislead users to think that cgroup supports proper cgroup-level
migration. Disallow rename(2) if sane_behavior.
v2: Fail with -EPERM instead of -EINVAL so that it matches the vfs
return value when ->rename is not implemented as suggested by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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We want these fixes here too.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There is a small race between when the cycle count is read from
the hardware and when the epoch stabilizes. Consider this
scenario:
CPU0 CPU1
---- ----
cyc = read_sched_clock()
cyc_to_sched_clock()
update_sched_clock()
...
cd.epoch_cyc = cyc;
epoch_cyc = cd.epoch_cyc;
...
epoch_ns + cyc_to_ns((cyc - epoch_cyc)
The cyc on cpu0 was read before the epoch changed. But we
calculate the nanoseconds based on the new epoch by subtracting
the new epoch from the old cycle count. Since epoch is most likely
larger than the old cycle count we calculate a large number that
will be converted to nanoseconds and added to epoch_ns, causing
time to jump forward too much.
Fix this problem by reading the hardware after the epoch has
stabilized.
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
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The MIPS interrupt controllers are all registering their own irq_domains
now. Drop the MIPS specific code because it is no longer needed.
Signed-off-by: Grant Likely <grant.likely@linaro.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5458/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull VFS fixes from Al Viro:
"Several fixes + obvious cleanup (you've missed a couple of open-coded
can_lookup() back then)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
snd_pcm_link(): fix a leak...
use can_lookup() instead of direct checks of ->i_op->lookup
move exit_task_namespaces() outside of exit_notify()
fput: task_work_add() can fail if the caller has passed exit_task_work()
ncpfs: fix rmdir returns Device or resource busy
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exit_notify() does exit_task_namespaces() after
forget_original_parent(). This was needed to ensure that ->nsproxy
can't be cleared prematurely, an exiting child we are going to
reparent can do do_notify_parent() and use the parent's (ours) pid_ns.
However, after 32084504 "pidns: use task_active_pid_ns in
do_notify_parent" ->nsproxy != NULL is no longer needed, we rely
on task_active_pid_ns().
Move exit_task_namespaces() from exit_notify() to do_exit(), after
exit_fs() and before exit_task_work().
This solves the problem reported by Andrey, free_ipc_ns()->shm_destroy()
does fput() which needs task_work_add().
Note: this particular problem can be fixed if we change fput(), and
that change makes sense anyway. But there is another reason to move
the callsite. The original reason for exit_task_namespaces() from
the middle of exit_notify() was subtle and it has already gone away,
now this looks confusing. And this allows us do simplify exit_notify(),
we can avoid unlock/lock(tasklist) and we can use ->exit_state instead
of PF_EXITING in forget_original_parent().
Reported-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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PARISC bootup triggers the warning at kernel/cpu/idle.c:96. That's
caused by the weak arch_cpu_idle() implementation, which is provided
to avoid that architectures implement idle_poll over and over.
The switchover to polling mode happens in the first call of the weak
arch_cpu_idle() implementation, but that code fails to reenable
interrupts and therefor triggers the warning.
Fix this by enabling interrupts in the weak arch_cpu_idle() code.
[ tglx: Made the changelog match the patch ]
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1371236142.2726.43.camel@dabdike
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cont is short for container. control group was named process container
at first, but then people found container already has a meaning in
linux kernel.
Clean up the leftover variable name @cont.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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A css (cgroup_subsys_state) is how each cgroup is represented to a
controller. As such, it can be used in hot paths across the various
subsystems different controllers are associated with.
One of the common operations is reference counting, which up until now
has been implemented using a global atomic counter and can have
significant adverse impact on scalability. For example, css refcnt
can be gotten and put multiple times by blkcg for each IO request.
For highops configurations which try to do as much per-cpu as
possible, the global frequent refcnting can be very expensive.
In general, given the various and hugely diverse paths css's end up
being used from, we need to make it cheap and highly scalable. In its
usage, css refcnting isn't very different from module refcnting.
This patch converts css refcnting to use the recently added
percpu_ref. css_get/tryget/put() directly maps to the matching
percpu_ref operations and the deactivation logic is no longer
necessary as percpu_ref already has refcnt killing.
The only complication is that as the refcnt is per-cpu,
percpu_ref_kill() in itself doesn't ensure that further tryget
operations will fail, which we need to guarantee before invoking
->css_offline()'s. This is resolved collecting kill confirmation
using percpu_ref_kill_and_confirm() and initiating the offline phase
of destruction after all css refcnt's are confirmed to be seen as
killed on all CPUs. The previous patches already splitted destruction
into two phases, so percpu_ref_kill_and_confirm() can be hooked up
easily.
This patch removes css_refcnt() which is used for rcu dereference
sanity check in css_id(). While we can add a percpu refcnt API to ask
the same question, css_id() itself is scheduled to be removed fairly
soon, so let's not bother with it. Just drop the sanity check and use
rcu_dereference_raw() instead.
v2: - init_cgroup_css() was calling percpu_ref_init() without checking
the return value. This causes two problems - the obvious lack
of error handling and percpu_ref_init() being called from
cgroup_init_subsys() before the allocators are up, which
triggers warnings but doesn't cause actual problems as the
refcnt isn't used for roots anyway. Fix both by moving
percpu_ref_init() to cgroup_create().
- The base references were put too early by
percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the
refs one extra time. This wasn't noticeable because css's go
through another RCU grace period before being freed. Update
cgroup_destroy_locked() to grab an extra reference before
killing the refcnts. This problem was noticed by Kent.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Kent Overstreet <koverstreet@google.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Alasdair G. Kergon" <agk@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Glauber Costa <glommer@gmail.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu into for-3.11
This is to receive percpu_refcount which will replace atomic_t
reference count in cgroup_subsys_state.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Split cgroup_destroy_locked() into two steps and put the latter half
into cgroup_offline_fn() which is executed from a work item. The
latter half is responsible for offlining the css's, removing the
cgroup from internal lists, and propagating release notification to
the parent. The separation is to allow using percpu refcnt for css.
Note that this allows for other cgroup operations to happen between
the first and second halves of destruction, including creating a new
cgroup with the same name. As the target cgroup is marked DEAD in the
first half and cgroup internals don't care about the names of cgroups,
this should be fine. A comment explaining this will be added by the
next patch which implements the actual percpu refcnting.
As RCU freeing is guaranteed to happen after the second step of
destruction, we can use the same work item for both. This patch
renames cgroup->free_work to ->destroy_work and uses it for both
purposes. INIT_WORK() is now performed right before queueing the work
item.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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This patch reorders the operations in cgroup_destroy_locked() such
that the userland visible parts happen before css offlining and
removal from the ->sibling list. This will be used to make css use
percpu refcnt.
While at it, split out CGRP_DEAD related comment from the refcnt
deactivation one and correct / clarify how different guarantees are
met.
While this patch changes the specific order of operations, it
shouldn't cause any noticeable behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU fixes from Paul McKenney:
"I must confess that this past merge window was not RCU's best showing.
This series contains three more fixes for RCU regressions:
1. A fix to __DECLARE_TRACE_RCU() that causes it to act as an
interrupt from idle rather than as a task switch from idle.
This change is needed due to the recent use of _rcuidle()
tracepoints that can be invoked from interrupt handlers as well
as from idle. Without this fix, invoking _rcuidle() tracepoints
from interrupt handlers results in splats and (more seriously)
confusion on RCU's part as to whether a given CPU is idle or not.
This confusion can in turn result in too-short grace periods and
therefore random memory corruption.
2. A fix to a subtle deadlock that could result due to RCU doing
a wakeup while holding one of its rcu_node structure's locks.
Although the probability of occurrence is low, it really
does happen. The fix, courtesy of Steven Rostedt, uses
irq_work_queue() to avoid the deadlock.
3. A fix to a silent deadlock (invisible to lockdep) due to the
interaction of timeouts posted by RCU debug code enabled by
CONFIG_PROVE_RCU_DELAY=y, grace-period initialization, and CPU
hotplug operations. This will not occur in production kernels,
but really does occur in randconfig testing. Diagnosis courtesy
of Steven Rostedt"
* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration
rcu: Don't call wakeup() with rcu_node structure ->lock held
trace: Allow idle-safe tracepoints to be called from irq
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cgroup->count tracks the number of css_sets associated with the cgroup
and used only to verify that no css_set is associated when the cgroup
is being destroyed. It's superflous as the destruction path can
simply check whether cgroup->cset_links is empty instead.
Drop cgroup->count and check ->cset_links directly from
cgroup_destroy_locked().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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__put_css_set() does RCU read access on @cgrp across dropping
@cgrp->count so that it can continue accessing @cgrp even if the count
reached zero and destruction of the cgroup commenced. Given that both
sides - __css_put() and cgroup_destroy_locked() - are cold paths, this
is unnecessary. Just making cgroup_destroy_locked() grab css_set_lock
while checking @cgrp->count is enough.
Remove the RCU read locking from __put_css_set() and make
cgroup_destroy_locked() read-lock css_set_lock when checking
@cgrp->count. This will also allow removing @cgrp->count.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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We will add another flag indicating that the cgroup is in the process
of being killed. REMOVING / REMOVED is more difficult to distinguish
and cgroup_is_removing()/cgroup_is_removed() are a bit awkward. Also,
later percpu_ref usage will involve "kill"ing the refcnt.
s/CGRP_REMOVED/CGRP_DEAD/
s/cgroup_is_removed()/cgroup_is_dead()
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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There's no point in using kmalloc() instead of the clearing variant
for trivial stuff. We can live dangerously elsewhere. Use kzalloc()
instead and drop 0 inits.
While at it, do trivial code reorganization in cgroup_file_open().
This patch doesn't introduce any functional changes.
v2: I was caught in the very distant past where list_del() didn't
poison and the initial version converted list_del()s to
list_del_init()s too. Li and Kent took me out of the stasis
chamber.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Acked-by: Li Zefan <lizefan@huawei.com>
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cgroups and css_sets are mapped M:N and this M:N mapping is
represented by struct cg_cgroup_link which forms linked lists on both
sides. The naming around this mapping is already confusing and struct
cg_cgroup_link exacerbates the situation quite a bit.
>From cgroup side, it starts off ->css_sets and runs through
->cgrp_link_list. From css_set side, it starts off ->cg_links and
runs through ->cg_link_list. This is rather reversed as
cgrp_link_list is used to iterate css_sets and cg_link_list cgroups.
Also, this is the only place which is still using the confusing "cg"
for css_sets. This patch cleans it up a bit.
* s/cgroup->css_sets/cgroup->cset_links/
s/css_set->cg_links/css_set->cgrp_links/
s/cgroup_iter->cg_link/cgroup_iter->cset_link/
* s/cg_cgroup_link/cgrp_cset_link/
* s/cgrp_cset_link->cg/cgrp_cset_link->cset/
s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/
s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/
* s/init_css_set_link/init_cgrp_cset_link/
s/free_cg_links/free_cgrp_cset_links/
s/allocate_cg_links/allocate_cgrp_cset_links/
* s/cgl[12]/link[12]/ in compare_css_sets()
* s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar
adustments.
* Comment and whiteline adjustments.
After the changes, we have
list_for_each_entry(link, &cont->cset_links, cset_link) {
struct css_set *cset = link->cset;
instead of
list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
struct css_set *cset = link->cg;
This patch is purely cosmetic.
v2: Fix broken sentences in the patch description.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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cgroup.c uses @cg for most struct css_set variables, which in itself
could be a bit confusing, but made much worse by the fact that there
are places which use @cg for struct cgroup variables.
compare_css_sets() epitomizes this confusion - @[old_]cg are struct
css_set while @cg[12] are struct cgroup.
It's not like the whole deal with cgroup, css_set and cg_cgroup_link
isn't already confusing enough. Let's give it some sanity by
uniformly using @cset for all struct css_set variables.
* s/cg/cset/ for all css_set variables.
* s/oldcg/old_cset/ s/oldcgrp/old_cgrp/. The same for the ones
prefixed with "new".
* s/cg/cgrp/ for cgroup variables in compare_css_sets().
* s/css/cset/ for the cgroup variable in task_cgroup_from_root().
* Whiteline adjustments.
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
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Before moving tasks out of empty cpusets, update_tasks_nodemask()
is called, which calls do_migrate_pages(xx, from, to). Then those
tasks are moved to an ancestor, and do_migrate_pages() is called
again.
The first time: from = node_to_be_offlined, to = empty.
The second time: from = empty, to = ancestor's nodemask.
so looks like no pages will be migrated.
Fix this by:
- Don't call update_tasks_nodemask() on empty cpusets.
- Pass cs->old_mems_allowed to do_migrate_pages().
v4: added comment in cpuset_hotplug_update_tasks() and rephased comment
in cpuset_attach().
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Currently some cpuset behaviors are not friendly when cpuset is co-mounted
with other cgroup controllers.
Now with this patchset if cpuset is mounted with sane_behavior option,
it behaves differently:
- Tasks will be kept in empty cpusets when hotplug happens and take
masks of ancestors with non-empty cpus/mems, instead of being moved to
an ancestor.
- A task can be moved into an empty cpuset, and again it takes masks of
ancestors, so the user can drop a task into a newly created cgroup without
having to do anything for it.
As tasks can reside in empy cpusets, here're some rules:
- They can be moved to another cpuset, regardless it's empty or not.
- Though it takes masks from ancestors, it takes other configs from the
empty cpuset.
- If the ancestors' masks are changed, those tasks will also be updated
to take new masks.
v2: add documentation in include/linux/cgroup.h
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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To achieve this:
- We call update_tasks_cpumask/nodemask() for empty cpusets when
hotplug happens, instead of moving tasks out of them.
- When a cpuset's masks are changed by writing cpuset.cpus/mems,
we also update tasks in child cpusets which are empty.
v3:
- do propagation work in one place for both hotplug and unplug
v2:
- drop rcu_read_lock before calling update_task_nodemask() and
update_task_cpumask(), instead of using workqueue.
- add documentation in include/linux/cgroup.h
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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effective_cpumask_cpuset() returns an ancestor cpuset which has
non-empty cpumask.
If a cpuset is empty and the tasks in it need to update their
cpus_allowed, they take on the ancestor cpuset's cpumask.
This currently won't change any behavior, but it will later allow us
to keep tasks in empty cpusets.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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