Commit Graph

8437 Commits

Author SHA1 Message Date
Hidetoshi Seto
0cf55e1ec0 sched, cputime: Introduce thread_group_times()
This is a real fix for problem of utime/stime values decreasing
described in the thread:

   http://lkml.org/lkml/2009/11/3/522

Now cputime is accounted in the following way:

 - {u,s}time in task_struct are increased every time when the thread
   is interrupted by a tick (timer interrupt).

 - When a thread exits, its {u,s}time are added to signal->{u,s}time,
   after adjusted by task_times().

 - When all threads in a thread_group exits, accumulated {u,s}time
   (and also c{u,s}time) in signal struct are added to c{u,s}time
   in signal struct of the group's parent.

So {u,s}time in task struct are "raw" tick count, while
{u,s}time and c{u,s}time in signal struct are "adjusted" values.

And accounted values are used by:

 - task_times(), to get cputime of a thread:
   This function returns adjusted values that originates from raw
   {u,s}time and scaled by sum_exec_runtime that accounted by CFS.

 - thread_group_cputime(), to get cputime of a thread group:
   This function returns sum of all {u,s}time of living threads in
   the group, plus {u,s}time in the signal struct that is sum of
   adjusted cputimes of all exited threads belonged to the group.

The problem is the return value of thread_group_cputime(),
because it is mixed sum of "raw" value and "adjusted" value:

  group's {u,s}time = foreach(thread){{u,s}time} + exited({u,s}time)

This misbehavior can break {u,s}time monotonicity.
Assume that if there is a thread that have raw values greater
than adjusted values (e.g. interrupted by 1000Hz ticks 50 times
but only runs 45ms) and if it exits, cputime will decrease (e.g.
-5ms).

To fix this, we could do:

  group's {u,s}time = foreach(t){task_times(t)} + exited({u,s}time)

But task_times() contains hard divisions, so applying it for
every thread should be avoided.

This patch fixes the above problem in the following way:

 - Modify thread's exit (= __exit_signal()) not to use task_times().
   It means {u,s}time in signal struct accumulates raw values instead
   of adjusted values.  As the result it makes thread_group_cputime()
   to return pure sum of "raw" values.

 - Introduce a new function thread_group_times(*task, *utime, *stime)
   that converts "raw" values of thread_group_cputime() to "adjusted"
   values, in same calculation procedure as task_times().

 - Modify group's exit (= wait_task_zombie()) to use this introduced
   thread_group_times().  It make c{u,s}time in signal struct to
   have adjusted values like before this patch.

 - Replace some thread_group_cputime() by thread_group_times().
   This replacements are only applied where conveys the "adjusted"
   cputime to users, and where already uses task_times() near by it.
   (i.e. sys_times(), getrusage(), and /proc/<PID>/stat.)

This patch have a positive side effect:

 - Before this patch, if a group contains many short-life threads
   (e.g. runs 0.9ms and not interrupted by ticks), the group's
   cputime could be invisible since thread's cputime was accumulated
   after adjusted: imagine adjustment function as adj(ticks, runtime),
     {adj(0, 0.9) + adj(0, 0.9) + ....} = {0 + 0 + ....} = 0.
   After this patch it will not happen because the adjustment is
   applied after accumulated.

v2:
 - remove if()s, put new variables into signal_struct.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4B162517.8040909@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-02 17:32:40 +01:00
Hidetoshi Seto
d99ca3b977 sched, cputime: Cleanups related to task_times()
- Remove if({u,s}t)s because no one call it with NULL now.
- Use cputime_{add,sub}().
- Add ifndef-endif for prev_{u,s}time since they are used
  only when !VIRT_CPU_ACCOUNTING.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4B1624C7.7040302@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-02 17:32:39 +01:00
Rusty Russell
bdddd2963c sched: Fix isolcpus boot option
Anton Blanchard wrote:

> We allocate and zero cpu_isolated_map after the isolcpus
> __setup option has run. This means cpu_isolated_map always
> ends up empty and if CPUMASK_OFFSTACK is enabled we write to a
> cpumask that hasn't been allocated.

I introduced this regression in 49557e6203 (sched: Fix
boot crash by zalloc()ing most of the cpu masks).

Use the bootmem allocator if they set isolcpus=, otherwise
allocate and zero like normal.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: peterz@infradead.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <200912021409.17013.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Anton Blanchard <anton@samba.org>
2009-12-02 10:27:16 +01:00
Tejun Heo
8592e6486a sched: Revert 498657a478
498657a478 incorrectly assumed
that preempt wasn't disabled around context_switch() and thus
was fixing imaginary problem.  It also broke KVM because it
depended on ->sched_in() to be called with irq enabled so that
it can do smp calls from there.

Revert the incorrect commit and add comment describing different
contexts under with the two callbacks are invoked.

Avi: spotted transposed in/out in the added comment.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Avi Kivity <avi@redhat.com>
Cc: peterz@infradead.org
Cc: efault@gmx.de
Cc: rusty@rustcorp.com.au
LKML-Reference: <1259726212-30259-2-git-send-email-tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-02 09:55:33 +01:00
Hidetoshi Seto
b7b20df91d sched, time: Define nsecs_to_jiffies()
Use of msecs_to_jiffies() for nsecs_to_cputime() have some
problems:

 - The type of msecs_to_jiffies()'s argument is unsigned int, so
   it cannot convert msecs greater than UINT_MAX = about 49.7 days.

 - msecs_to_jiffies() returns MAX_JIFFY_OFFSET if MSB of argument
   is set, assuming that input was negative value.  So it cannot
   convert msecs greater than INT_MAX = about 24.8 days too.

This patch defines a new function nsecs_to_jiffies() that can
deal greater values, and that can deal all incoming values as
unsigned.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Amrico Wang <xiyou.wangcong@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@linux.vnet.ibm.com>
LKML-Reference: <4B0E16E7.5070307@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 12:59:20 +01:00
Hidetoshi Seto
d5b7c78e97 sched: Remove task_{u,s,g}time()
Now all task_{u,s}time() pairs are replaced by task_times().
And task_gtime() is too simple to be an inline function.

Cleanup them all.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16D1.70902@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 12:59:20 +01:00
Hidetoshi Seto
d180c5bcce sched: Introduce task_times() to replace task_{u,s}time() pair
Functions task_{u,s}time() are called in pair in almost all
cases.  However task_stime() is implemented to call task_utime()
from its inside, so such paired calls run task_utime() twice.

It means we do heavy divisions (div_u64 + do_div) twice to get
utime and stime which can be obtained at same time by one set
of divisions.

This patch introduces a function task_times(*tsk, *utime,
*stime) to retrieve utime and stime at once in better, optimized
way.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16AE.906@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 12:59:19 +01:00
Ingo Molnar
16bc67edeb Merge branch 'sched/urgent' into sched/core
Merge reason: Pick up fixes that did not make it into .32.0

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 10:50:42 +01:00
Mike Travis
f6630114d9 sched: Limit the number of scheduler debug messages
Remove the verbose scheduler debug messages unless kernel
parameter "sched_debug" set.  /proc/sched_debug unchanged.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091118002221.489305000@alcatraz.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 10:17:30 +01:00
Shmulik Ladkani
93335a2155 sched.c: Call debug_show_all_locks() when dumping all tasks
In commit v2.6.21-691-g39bc89f ("make SysRq-T show all tasks
again") the interface of show_state_filter() was changed: zero
valued 'state_filter' specifies "dump all tasks" (instead of -1).

However, the condition for calling debug_show_all_locks() ("show
locks if all tasks are dumped") was not updated accordingly.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Cc: peterz@infradead.org
LKML-Reference: <4b0d2fe4.0ab6660a.6437.3cfc@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-25 14:26:52 +01:00
Tim Blechmann
710390d90f sched: Optimize branch hint in context_switch()
Branch hint profiling on my nehalem machine showed over 90%
incorrect branch hints:

  10420275 170645395  94 context_switch                 sched.c
   3043
  10408421 171098521  94 context_switch                 sched.c
   3050

Signed-off-by: Tim Blechmann <tim@klingt.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B0BBB9F.6080304@klingt.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-24 12:18:42 +01:00
Tim Blechmann
36ace27e3e sched: Optimize branch hint in pick_next_task_fair()
Branch hint profiling on my nehalem machine showed 90%
incorrect branch hints:

  15728471 158903754  90 pick_next_task_fair
  sched_fair.c    1555

Signed-off-by: Tim Blechmann <tim@klingt.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B0BBBB1.2050100@klingt.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-24 12:18:12 +01:00
Jan Blunck
429947248f sched_feat_write(): Update ppos instead of file->f_pos
sched_feat_write() should update ppos instead of file->f_pos.

(This reduces some BKL dependencies of this code.)

Signed-off-by: Jan Blunck <jblunck@suse.de>
Cc: jkacur@redhat.com
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jamie Lokier <jamie@shareable.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
LKML-Reference: <1258735245-25826-8-git-send-email-jblunck@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-23 19:38:03 +01:00
Peter Zijlstra
047106adcc sched: Sched_rt_periodic_timer vs cpu hotplug
Heiko reported a case where a timer interrupt managed to
reference a root_domain structure that was already freed by a
concurrent hot-un-plug operation.

Solve this like the regular sched_domain stuff is also
synchronized, by adding a synchronize_sched() stmt to the free
path, this ensures that a root_domain stays present for any
atomic section that could have observed it.

Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Siddha Suresh B <suresh.b.siddha@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
LKML-Reference: <1258363873.26714.83.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-16 10:46:27 +01:00
Tejun Heo
498657a478 sched, kvm: Fix race condition involving sched_in_preempt_notifers
In finish_task_switch(), fire_sched_in_preempt_notifiers() is
called after finish_lock_switch().

However, depending on architecture, preemption can be enabled after
finish_lock_switch() which breaks the semantics of preempt
notifiers.

So move it before finish_arch_switch(). This also makes the in-
notifiers symmetric to out- notifiers in terms of locking - now
both are called under rq lock.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4AFD2801.7020900@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-15 09:59:54 +01:00
Peter Zijlstra
fe3bcfe1f6 sched: More generic WAKE_AFFINE vs select_idle_sibling()
Instead of only considering SD_WAKE_AFFINE | SD_PREFER_SIBLING
domains also allow all SD_PREFER_SIBLING domains below a
SD_WAKE_AFFINE domain to change the affinity target.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091112145610.909723612@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-13 10:09:59 +01:00
Peter Zijlstra
a50bde5130 sched: Cleanup select_task_rq_fair()
Clean up the new affine to idle sibling bits while trying to
grok them. Should not have any function differences.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091112145610.832503781@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-13 10:09:58 +01:00
Hidetoshi Seto
761b1d26df sched: Fix granularity of task_u/stime()
Originally task_s/utime() were designed to return clock_t but
later changed to return cputime_t by following commit:

  commit efe567fc82
  Author: Christian Borntraeger <borntraeger@de.ibm.com>
  Date:   Thu Aug 23 15:18:02 2007 +0200

It only changed the type of return value, but not the
implementation. As the result the granularity of task_s/utime()
is still that of clock_t, not that of cputime_t.

So using task_s/utime() in __exit_signal() makes values
accumulated to the signal struct to be rounded and coarse
grained.

This patch removes casts to clock_t in task_u/stime(), to keep
granularity of cputime_t over the calculation.

v2:
  Use div_u64() to avoid error "undefined reference to `__udivdi3`"
  on some 32bit systems.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: xiyou.wangcong@gmail.com
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4AFB9029.9000208@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-12 15:23:47 +01:00
Mike Galbraith
055a00865d sched: Fix/add missing update_rq_clock() calls
kthread_bind(), migrate_task() and sched_fork were missing
updates, and try_to_wake_up() was updating after having already
used the stale clock.

Aside from preventing potential latency hits, there' a side
benefit in that early boot printk time stamps become monotonic.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1258020464.6491.2.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
2009-11-12 12:28:29 +01:00
Linus Torvalds
961767b75d Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
  highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow
  rcu: Fix long-grace-period race between forcing and initialization
  uids: Prevent tear down race
2009-11-11 11:30:15 -08:00
Linus Torvalds
1fd18a871a Merge branch 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  genirq: try_one_irq() must be called with irq disabled
2009-11-11 11:29:58 -08:00
Peter Zijlstra
ffd44db5f0 sched: Make sure task has correct sched_class after policy change
From the code in rt_mutex_setprio(), it is evident that the
intention is that task's with a RT 'prio' value as a consequence
of receiving a PI boost also have their 'sched_class' field set
to '&rt_sched_class'.

However, Peter noticed that the code in __setscheduler() could
result in this intention being frustrated. Fix it.

Reported-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1257880321.4108.457.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-10 20:22:31 +01:00
Mike Galbraith
eae0c9dfb5 sched: Fix and clean up rate-limit newidle code
Commit 1b9508f, "Rate-limit newidle" has been confirmed to fix
the netperf UDP loopback regression reported by Alex Shi.

This is a cleanup and a fix:

 - moved to a more out of the way spot

 - fix to ensure that balancing doesn't try to balance
   runqueues which haven't gone online yet, which can
   mess up CPU enumeration during boot.

Reported-by: Alex Shi <alex.shi@intel.com>
Reported-by: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org> # .32.x: a1f84a3: sched: Check for an idle shared cache
Cc: <stable@kernel.org> # .32.x: 1b9508f: sched: Rate-limit newidle
Cc: <stable@kernel.org> # .32.x: fd21073: sched: Fix affinity logic
Cc: <stable@kernel.org> # .32.x
LKML-Reference: <1257821402.5648.17.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-10 04:25:58 +01:00
Lai Jiangshan
d8c80ce091 sched, no_hz: Remove unused rq->last_tick_seen field
In 15934a3732,
field last_tick_seen is added to struct rq.
But it is unused now.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Guillaume Chazarain <guichaz@yahoo.fr>
LKML-Reference: <4AE6A513.6010100@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-08 13:17:47 +01:00
Cyrill Gorcunov
e9036b36ee sched: Use root_task_group_empty only with FAIR_GROUP_SCHED
root_task_group_empty is used only with FAIR_GROUP_SCHED
so if we use other scheduler options we get:

  kernel/sched.c:314: warning: 'root_task_group_empty' defined but not used

So move CONFIG_FAIR_GROUP_SCHED up that it covers
root_task_group_empty().

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091026192414.GB5321@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-08 13:15:48 +01:00
Randy Dunlap
968c86458a sched: Fix kernel-doc function parameter name
Fix variable name in sched.c kernel-doc notation.

Fixes this DocBook warning:

 Warning(kernel/sched.c:2008): No description found for parameter
 'p' Warning(kernel/sched.c:2008): Excess function parameter 'k'
 description in 'kthread_bind'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <4AF4B1BC.8020604@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-08 11:26:25 +01:00
Yong Zhang
e7e7e0c084 genirq: try_one_irq() must be called with irq disabled
Prarit reported:
=================================
[ INFO: inconsistent lock state ]
2.6.32-rc5 #1
---------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
swapper/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
 (&irq_desc_lock_class){?.-...}, at: [<ffffffff810c264e>] try_one_irq+0x32/0x138
{IN-HARDIRQ-W} state was registered at:
 [<ffffffff81095160>] __lock_acquire+0x2fc/0xd5d
 [<ffffffff81095cb4>] lock_acquire+0xf3/0x12d
 [<ffffffff814cdadd>] _spin_lock+0x40/0x89
 [<ffffffff810c3389>] handle_level_irq+0x30/0x105
 [<ffffffff81014e0e>] handle_irq+0x95/0xb7
 [<ffffffff810141bd>] do_IRQ+0x6a/0xe0
 [<ffffffff81012813>] ret_from_intr+0x0/0x16
irq event stamp: 195096
hardirqs last  enabled at (195096): [<ffffffff814cd7f7>] _spin_unlock_irq+0x3a/0x5c
hardirqs last disabled at (195095): [<ffffffff814cdbdd>] _spin_lock_irq+0x29/0x95
softirqs last  enabled at (195088): [<ffffffff81068c92>] __do_softirq+0x1c1/0x1ef
softirqs last disabled at (195093): [<ffffffff8101304c>] call_softirq+0x1c/0x30

other info that might help us debug this:
1 lock held by swapper/0:
 #0:  (kernel/irq/spurious.c:21){+.-...}, at: [<ffffffff81070cf2>]
run_timer_softirq+0x1a9/0x315

stack backtrace:
Pid: 0, comm: swapper Not tainted 2.6.32-rc5 #1
Call Trace:
 <IRQ>  [<ffffffff81093e94>] valid_state+0x187/0x1ae
 [<ffffffff81093fe4>] mark_lock+0x129/0x253
 [<ffffffff810951d4>] __lock_acquire+0x370/0xd5d
 [<ffffffff81095cb4>] lock_acquire+0xf3/0x12d
 [<ffffffff814cdadd>] _spin_lock+0x40/0x89
 [<ffffffff810c264e>] try_one_irq+0x32/0x138
 [<ffffffff810c2795>] poll_all_shared_irqs+0x41/0x6d
 [<ffffffff810c27dd>] poll_spurious_irqs+0x1c/0x49
 [<ffffffff81070d82>] run_timer_softirq+0x239/0x315
 [<ffffffff81068bd3>] __do_softirq+0x102/0x1ef
 [<ffffffff8101304c>] call_softirq+0x1c/0x30
 [<ffffffff81014b65>] do_softirq+0x59/0xca
 [<ffffffff810686ad>] irq_exit+0x58/0xae
 [<ffffffff81029b84>] smp_apic_timer_interrupt+0x94/0xba
 [<ffffffff81012a33>] apic_timer_interrupt+0x13/0x20

The reason is that try_one_irq() is called from hardirq context with
interrupts disabled and from softirq context (poll_all_shared_irqs())
with interrupts enabled.

Disable interrupts before calling it from poll_all_shared_irqs().

Reported-and-tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
LKML-Reference: <1257563773-4620-1-git-send-email-yong.zhang0@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-11-07 21:44:45 +01:00
Linus Torvalds
608221fdf9 Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Fix kthread_bind() by moving the body of kthread_bind() to sched.c
  sched: Disable SD_PREFER_LOCAL at node level
  sched: Fix boot crash by zalloc()ing most of the cpu masks
  sched: Strengthen buddies and mitigate buddy induced latencies
2009-11-05 10:56:47 -08:00
Linus Torvalds
72cc129e8d Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  ftrace: Fix unmatched locking in ftrace_regex_write()
  ring-buffer: Synchronize resizing buffer with reader lock
2009-11-05 10:56:25 -08:00
Mike Galbraith
fd210738f6 sched: Fix affinity logic in select_task_rq_fair()
Ingo Molnar reported:

[   26.804000] BUG: using smp_processor_id() in preemptible [00000000] code: events/1/10
[   26.808000] caller is vmstat_update+0x26/0x70
[   26.812000] Pid: 10, comm: events/1 Not tainted 2.6.32-rc5 #6887
[   26.816000] Call Trace:
[   26.820000]  [<c1924a24>] ? printk+0x28/0x3c
[   26.824000]  [<c13258a0>] debug_smp_processor_id+0xf0/0x110
[   26.824000] mount used greatest stack depth: 1464 bytes left
[   26.828000]  [<c111d086>] vmstat_update+0x26/0x70
[   26.832000]  [<c1086418>] worker_thread+0x188/0x310
[   26.836000]  [<c10863b7>] ? worker_thread+0x127/0x310
[   26.840000]  [<c108d310>] ? autoremove_wake_function+0x0/0x60
[   26.844000]  [<c1086290>] ? worker_thread+0x0/0x310
[   26.848000]  [<c108cf0c>] kthread+0x7c/0x90
[   26.852000]  [<c108ce90>] ? kthread+0x0/0x90
[   26.856000]  [<c100c0a7>] kernel_thread_helper+0x7/0x10
[   26.860000] BUG: using smp_processor_id() in preemptible [00000000] code: events/1/10
[   26.864000] caller is vmstat_update+0x3c/0x70

Because this commit:

  a1f84a3: sched: Check for an idle shared cache in select_task_rq_fair()

broke ->cpus_allowed.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: arjan@infradead.org
Cc: <stable@kernel.org>
LKML-Reference: <1257415066.12867.1.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-05 11:01:39 +01:00
Mike Galbraith
1b9508f683 sched: Rate-limit newidle
Rate limit newidle to migration_cost. It's a win for all
stages of sysbench oltp tests.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 19:13:48 +01:00
Mike Galbraith
a1f84a3ab8 sched: Check for an idle shared cache in select_task_rq_fair()
When waking affine, check for an idle shared cache, and if
found, wake to that CPU/sibling instead of the waker's CPU.

This improves pgsql+oltp ramp up by roughly 8%. Possibly more
for other loads, depending on overlap. The trade-off is a
roughly 1% peak downturn if tasks are truly synchronous.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@kernel.org>
LKML-Reference: <1256654138.17752.7.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 18:46:22 +01:00
Rusty Russell
acc3f5d7ca cpumask: Partition_sched_domains takes array of cpumask_var_t
Currently partition_sched_domains() takes a 'struct cpumask
*doms_new' which is a kmalloc'ed array of cpumask_t.  You can't
have such an array if 'struct cpumask' is undefined, as we plan
for CONFIG_CPUMASK_OFFSTACK=y.

So, we make this an array of cpumask_var_t instead: this is the
same for the CONFIG_CPUMASK_OFFSTACK=n case, but requires
multiple allocations for the CONFIG_CPUMASK_OFFSTACK=y case.
Hence we add alloc_sched_domains() and free_sched_domains()
functions.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <200911031453.40668.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 13:16:40 +01:00
Rusty Russell
e2c8806304 cpumask: Simplify sched_rt.c
find_lowest_rq() wants to call pick_optimal_cpu() on the
intersection of sched_domain_span(sd) and lowest_mask.  Rather
than doing a cpus_and into a temporary, we can open-code it.

This actually makes the code slightly clearer, IMHO.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Gregory Haskins <ghaskins@novell.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <200911031453.15350.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 13:16:38 +01:00
Hiroshi Shimamoto
9824a2b728 sched: Remove unused cpu_nr_migrations()
cpu_nr_migrations() is not used, remove it.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4AF12A66.6020609@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 11:43:43 +01:00
Hiroshi Shimamoto
1477b6a7ed sched: Remove unused __schedule() declaration
__schedule() had been removed.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4AF129C8.3030008@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-04 11:43:42 +01:00
Li Zefan
ed146b2594 ftrace: Fix unmatched locking in ftrace_regex_write()
When a command is passed to the set_ftrace_filter, then
the ftrace_regex_lock is still held going back to user space.

 # echo 'do_open : foo' > set_ftrace_filter
 (still holding ftrace_regex_lock when returning to user space!)

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4AEF7F8A.3080300@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-11-04 01:42:10 -05:00
Lai Jiangshan
f7112949f6 ring-buffer: Synchronize resizing buffer with reader lock
We got a sudden panic when we reduced the size of the
ringbuffer.

We can reproduce the panic by the following steps:

echo 1 > events/sched/enable
cat trace_pipe > /dev/null &

while ((1))
do
echo 12000 > buffer_size_kb
echo 512 > buffer_size_kb
done

(not more than 5 seconds, panic ...)

Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4AF01735.9060409@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-11-04 00:04:20 -05:00
Linus Torvalds
38dc63459f Merge branch 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6
* 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6:
  PM: Remove some debug messages producing too much noise
  PM: Fix warning on suspend errors
  PM / Hibernate: Add newline to load_image() fail path
  PM / Hibernate: Fix error handling in save_image()
  PM / Hibernate: Fix blkdev refleaks
  PM / yenta: Split resume into early and late parts (rev. 4)
2009-11-03 07:52:57 -08:00
Ian Campbell
1d51075094 Correct nr_processes() when CPUs have been unplugged
nr_processes() returns the sum of the per cpu counter process_counts for
all online CPUs. This counter is incremented for the current CPU on
fork() and decremented for the current CPU on exit(). Since a process
does not necessarily fork and exit on the same CPU the process_count for
an individual CPU can be either positive or negative and effectively has
no meaning in isolation.

Therefore calculating the sum of process_counts over only the online
CPUs omits the processes which were started or stopped on any CPU which
has since been unplugged. Only the sum of process_counts across all
possible CPUs has meaning.

The only caller of nr_processes() is proc_root_getattr() which
calculates the number of links to /proc as
        stat->nlink = proc_root.nlink + nr_processes();

You don't have to be all that unlucky for the nr_processes() to return a
negative value leading to a negative number of links (or rather, an
apparently enormous number of links). If this happens then you can get
failures where things like "ls /proc" start to fail because they got an
-EOVERFLOW from some stat() call.

Example with some debugging inserted to show what goes on:
        # ps haux|wc -l
        nr_processes: CPU0:     90
        nr_processes: CPU1:     1030
        nr_processes: CPU2:     -900
        nr_processes: CPU3:     -136
        nr_processes: TOTAL:    84
        proc_root_getattr. nlink 12 + nr_processes() 84 = 96
        84
        # echo 0 >/sys/devices/system/cpu/cpu1/online
        # ps haux|wc -l
        nr_processes: CPU0:     85
        nr_processes: CPU2:     -901
        nr_processes: CPU3:     -137
        nr_processes: TOTAL:    -953
        proc_root_getattr. nlink 12 + nr_processes() -953 = -941
        75
        # stat /proc/
        nr_processes: CPU0:     84
        nr_processes: CPU2:     -901
        nr_processes: CPU3:     -137
        nr_processes: TOTAL:    -954
        proc_root_getattr. nlink 12 + nr_processes() -954 = -942
          File: `/proc/'
          Size: 0               Blocks: 0          IO Block: 1024   directory
        Device: 3h/3d   Inode: 1           Links: 4294966354
        Access: (0555/dr-xr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
        Access: 2009-11-03 09:06:55.000000000 +0000
        Modify: 2009-11-03 09:06:55.000000000 +0000
        Change: 2009-11-03 09:06:55.000000000 +0000

I'm not 100% convinced that the per_cpu regions remain valid for offline
CPUs, although my testing suggests that they do. If not then I think the
correct solution would be to aggregate the process_count for a given CPU
into a global base value in cpu_down().

This bug appears to pre-date the transition to git and it looks like it
may even have been present in linux-2.6.0-test7-bk3 since it looks like
the code Rusty patched in http://lwn.net/Articles/64773/ was already
wrong.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-11-03 07:52:39 -08:00
Jiri Slaby
bf9fd67a03 PM / Hibernate: Add newline to load_image() fail path
Finish a line by \n when load_image fails in the middle of loading.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2009-11-03 11:03:09 +01:00
Jiri Slaby
4ff277f9e4 PM / Hibernate: Fix error handling in save_image()
There are too many retval variables in save_image(). Thus error return
value from snapshot_read_next() may be ignored and only part of the
snapshot (successfully) written.

Remove 'error' variable, invert the condition in the do-while loop
and convert the loop to use only 'ret' variable.

Switch the rest of the function to consider only 'ret'.

Also make sure we end printed line by \n if an error occurs.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2009-11-03 11:02:43 +01:00
Jiri Slaby
76b57e613f PM / Hibernate: Fix blkdev refleaks
While cruising through the swsusp code I found few blkdev reference
leaks of resume_bdev.

swsusp_read: remove blkdev_put altogether. Some fail paths do
             not do that.
swsusp_check: make sure we always put a reference on fail paths
software_resume: all fail paths between swsusp_check and swsusp_read
                 omit swsusp_close. Add it in those cases. And since
                 swsusp_read doesn't drop the reference anymore, do
                 it here unconditionally.

[rjw: Fixed a small coding style issue.]

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2009-11-03 11:01:46 +01:00
Mike Galbraith
b84ff7d6f1 sched: Fix kthread_bind() by moving the body of kthread_bind() to sched.c
Eric Paris reported that commit
f685ceacab causes boot time
PREEMPT_DEBUG complaints.

 [    4.590699] BUG: using smp_processor_id() in preemptible [00000000] code: rmmod/1314
 [    4.593043] caller is task_hot+0x86/0xd0

Since kthread_bind() messes with scheduler internals, move the
body to sched.c, and lock the runqueue.

Reported-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Tested-by: Eric Paris <eparis@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1256813310.7574.3.camel@marge.simson.net>
[ v2: fix !SMP build and clean up ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-03 07:25:00 +01:00
Linus Torvalds
3fe866ca6c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  futex: Fix spurious wakeup for requeue_pi really
2009-11-02 09:46:33 -08:00
Linus Torvalds
bce8fc4cb7 Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf tools: Remove -Wcast-align
  perf tools: Fix compatibility with libelf 0.8 and autodetect
  perf events: Don't generate events for the idle task when exclude_idle is set
  perf events: Fix swevent hrtimer sampling by keeping track of remaining time when enabling/disabling swevent hrtimers
2009-11-02 09:46:06 -08:00
Linus Torvalds
a5e3013d66 Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: Remove cpu arg from the rb_time_stamp() function
  tracing: Fix comment typo and documentation example
  tracing: Fix trace_seq_printf() return value
  tracing: Update *ppos instead of filp->f_pos
2009-11-02 09:45:44 -08:00
Paul E. McKenney
83f5b01ffb rcu: Fix long-grace-period race between forcing and initialization
Very long RCU read-side critical sections (50 milliseconds or
so) can cause a race between force_quiescent_state() and
rcu_start_gp() as follows on kernel builds with multi-level
rcu_node hierarchies:

1.	CPU 0 calls force_quiescent_state(), sees that there is a
	grace period in progress, and acquires ->fsqlock.

2.	CPU 1 detects the end of the grace period, and so
	cpu_quiet_msk_finish() sets rsp->completed to rsp->gpnum.
	This operation is carried out under the root rnp->lock,
	but CPU 0 has not yet acquired that lock.  Note that
	rsp->signaled is still RCU_SAVE_DYNTICK from the last
	grace period.

3.	CPU 1 calls rcu_start_gp(), but no one wants a new grace
	period, so it drops the root rnp->lock and returns.

4.	CPU 0 acquires the root rnp->lock and picks up rsp->completed
	and rsp->signaled, then drops rnp->lock.  It then enters the
	RCU_SAVE_DYNTICK leg of the switch statement.

5.	CPU 2 invokes call_rcu(), and now needs a new grace period.
	It calls rcu_start_gp(), which acquires the root rnp->lock, sets
	rsp->signaled to RCU_GP_INIT (too bad that CPU 0 is already in
	the RCU_SAVE_DYNTICK leg of the switch statement!)  and starts
	initializing the rcu_node hierarchy.  If there are multiple
	levels to the hierarchy, it will drop the root rnp->lock and
	initialize the lower levels of the hierarchy.

6.	CPU 0 notes that rsp->completed has not changed, which permits
        both CPU 2 and CPU 0 to try updating it concurrently.  If CPU 0's
	update prevails, later calls to force_quiescent_state() can
	count old quiescent states against the new grace period, which
	can in turn result in premature ending of grace periods.

	Not good.

This patch adds an RCU_GP_IDLE state for rsp->signaled that is
set initially at boot time and any time a grace period ends.
This prevents CPU 0 from getting into the workings of
force_quiescent_state() in step 4.  Additional locking and
checks prevent the concurrent update of rsp->signaled in step 6.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1256742889199-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-02 16:06:21 +01:00
Thomas Gleixner
b00bc0b237 uids: Prevent tear down race
Ingo triggered the following warning:

WARNING: at lib/debugobjects.c:255 debug_print_object+0x42/0x50()
Hardware name: System Product Name
ODEBUG: init active object type: timer_list
Modules linked in:
Pid: 2619, comm: dmesg Tainted: G        W  2.6.32-rc5-tip+ #5298
Call Trace:
 [<81035443>] warn_slowpath_common+0x6a/0x81
 [<8120e483>] ? debug_print_object+0x42/0x50
 [<81035498>] warn_slowpath_fmt+0x29/0x2c
 [<8120e483>] debug_print_object+0x42/0x50
 [<8120ec2a>] __debug_object_init+0x279/0x2d7
 [<8120ecb3>] debug_object_init+0x13/0x18
 [<810409d2>] init_timer_key+0x17/0x6f
 [<81041526>] free_uid+0x50/0x6c
 [<8104ed2d>] put_cred_rcu+0x61/0x72
 [<81067fac>] rcu_do_batch+0x70/0x121

debugobjects warns about an enqueued timer being initialized. If
CONFIG_USER_SCHED=y the user management code uses delayed work to
remove the user from the hash table and tear down the sysfs objects.

free_uid is called from RCU and initializes/schedules delayed work if
the usage count of the user_struct is 0. The init/schedule happens
outside of the uidhash_lock protected region which allows a concurrent
caller of find_user() to reference the about to be destroyed
user_struct w/o preventing the work from being scheduled. If the next
free_uid call happens before the work timer expired then the active
timer is initialized and the work scheduled again.

The race was introduced in commit 5cb350ba (sched: group scheduling,
sysfs tunables) and made more prominent by commit 3959214f (sched:
delayed cleanup of user_struct)

Move the init/schedule_delayed_work inside of the uidhash_lock
protected region to prevent the race.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: stable@kernel.org
2009-11-02 16:02:39 +01:00
Rusty Russell
49557e6203 sched: Fix boot crash by zalloc()ing most of the cpu masks
I got a boot crash when forcing cpumasks offstack on 32 bit,
because find_new_ilb() returned 3 on my UP system (nohz.cpu_mask
wasn't zeroed).

AFAICT the others need to be zeroed too: only
nohz.ilb_grp_nohz_mask is initialized before use.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <200911022037.21282.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-02 15:48:54 +01:00