Commit Graph

3938 Commits

Author SHA1 Message Date
Paul E. McKenney
e3d7be270c rcu, rcutorture: make quiescent rcutorture less power-hungry
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: josh@freedesktop.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: dino@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Cc: vegard.nossum@gmail.com
Cc: adobriyan@gmail.com
Cc: oleg@tv-sign.ru
Cc: bunk@kernel.org
Cc: rjw@sisk.pl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-24 13:36:38 +02:00
Ingo Molnar
1e74f9cbbb Merge branch 'linus' into core/rcu 2008-06-23 11:29:11 +02:00
Linus Torvalds
1f1e2ce8a5 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:
  softlockup: fix NMI hangs due to lock race - 2.6.26-rc regression
  rcupreempt: remove export of rcu_batches_completed_bh
  cpuset: limit the input of cpuset.sched_relax_domain_level
2008-06-20 12:37:13 -07:00
Bharath Ravi
d4abc238c9 sched, delay accounting: fix incorrect delay time when constantly waiting on runqueue
This patch corrects the incorrect value of per process run-queue wait
time reported by delay statistics. The anomaly was due to the following
reason. When a process leaves the CPU and immediately starts waiting for
CPU on the runqueue (which means it remains in the TASK_RUNNABLE state),
the time of re-entry into the run-queue is never recorded. Due to this,
the waiting time on the runqueue from this point of re-entry upto the
next time it hits the CPU is not accounted for. This is solved by
recording the time of re-entry of a process leaving the CPU in the
sched_info_depart() function IF the process will go back to waiting on
the run-queue. This IF condition is verified by checking whether the
process is still in the TASK_RUNNABLE state.

The patch was tested on 2.6.26-rc6 using two simple CPU hog programs.
The values noted prior to the fix did not account for the time spent on
the runqueue waiting. After the fix, the correct values were reported
back to user space.

Signed-off-by: Bharath Ravi <bharathravi1@gmail.com>
Signed-off-by: Madhava K R  <madhavakr@gmail.com>
Cc: dhaval@linux.vnet.ibm.com
Cc: vatsa@in.ibm.com
Cc: balbir@in.ibm.com
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 14:15:28 +02:00
Paul E. McKenney
31a72bce0b rcu: make rcutorture more vicious: reinstate boot-time testing
This patch re-institutes the ability to build rcutorture directly into
the Linux kernel.  The reason that this capability was removed was that
this could result in your kernel being pretty much useless, as rcutorture
would be running starting from early boot.  This problem has been avoided
by (1) making rcutorture run only three seconds of every six by default,
(2) adding a CONFIG_RCU_TORTURE_TEST_RUNNABLE that permits rcutorture
to be quiesced at boot time, and (3) adding a sysctl in /proc named
/proc/sys/kernel/rcutorture_runnable that permits rcutorture to be
quiesced and unquiesced when built into the kernel.

Please note that this /proc file is -not- available when rcutorture
is built as a module.  Please also note that to get the earlier
take-no-prisoners behavior, you must use the boot command line to set
rcutorture's "stutter" parameter to zero.

The rcutorture quiescing mechanism is currently quite crude: loops
in each rcutorture process that poll a global variable once per tick.
Suggestions for improvement are welcome.  The default action will
be to reduce the polling rate to a few times per second.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 11:22:15 +02:00
Jason Wessel
9c106c119e softlockup: fix NMI hangs due to lock race - 2.6.26-rc regression
The touch_nmi_watchdog() routine on x86 ultimately calls
touch_softlockup_watchdog().  The problem is that to touch the
softlockup watchdog, the cpu_clock code has to be called which could
involve multiple cpu locks and can lead to a hard hang if one of the
locks is held by a processor that is not going to return anytime soon
(such as could be the case with kgdb or perhaps even with some other
kind of exception).

This patch causes the public version of the
touch_softlockup_watchdog() to defer the cpu clock access to a later
point.

The test case for this problem is to use the following kernel config
options:

CONFIG_KGDB_TESTS=y
CONFIG_KGDB_TESTS_ON_BOOT=y
CONFIG_KGDB_TESTS_BOOT_STRING="V1F100I100000"

It should be noted that kgdb test suite and these options were not
available until 2.6.26-rc2, so it was necessary to patch the kgdb
test suite during the bisection.

I would consider this patch a regression fix because the problem first
appeared in commit 27ec440779 when some
logic was added to try to periodically sync the clocks.  It was
possible to work around this particular problem by simply not
performing the sync anytime the system was in a critical context.
This was ok until commit 3e51f33fcc,
which added config option CONFIG_HAVE_UNSTABLE_SCHED_CLOCK and some
multi-cpu locks to sync the clocks.  It became clear that accessing
this code from an nmi was the source of the lockups.  Avoiding the
access to the low level clock code from an code inside the NMI
processing also fixed the problem with the 27ec44... commit.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:45:38 +02:00
Steven Rostedt
afd38009cc rcupreempt: remove export of rcu_batches_completed_bh
In rcupreempt, rcu_batches_completed_bh is defined as a static inline in
the header file. This does not need to be exported, and not only that,
this breaks my PPC build.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: paulus@samba.org
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-19 09:45:37 +02:00
Li Zefan
30e0e17819 cpuset: limit the input of cpuset.sched_relax_domain_level
We allow the inputs to be [-1 ... SD_LV_MAX), and return -EINVAL
for inputs outside this range.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Paul Jackson <pj@sgi.com>
Acked-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-19 09:45:36 +02:00
Max Krasnyansky
f18f982abf sched: CPU hotplug events must not destroy scheduler domains created by the cpusets
First issue is not related to the cpusets. We're simply leaking doms_cur.
It's allocated in arch_init_sched_domains() which is called for every
hotplug event. So we just keep reallocation doms_cur without freeing it.
I introduced free_sched_domains() function that cleans things up.

Second issue is that sched domains created by the cpusets are
completely destroyed by the CPU hotplug events. For all CPU hotplug
events scheduler attaches all CPUs to the NULL domain and then puts
them all into the single domain thereby destroying domains created
by the cpusets (partition_sched_domains).
The solution is simple, when cpusets are enabled scheduler should not
create default domain and instead let cpusets do that. Which is
exactly what the patch does.

Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
Cc: pj@sgi.com
Cc: menage@google.com
Cc: rostedt@goodmis.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-06-19 09:14:51 +02:00
Peter Zijlstra
15a8641ead sched: rt-group: fix RR buglet
In tick_task_rt() we first call update_curr_rt() which can dequeue a runqueue
due to it running out of runtime, and then we try to requeue it, of it also
having exhausted its RR quota. Obviously requeueing something that is no longer
on the runqueue will not have the expected result.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Daniel K. <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:59 +02:00
Peter Zijlstra
ad2a3f13b7 sched: rt-group: heirarchy aware throttle
The bandwidth throttle code dequeues a group when it runs out of quota, and
re-queues it once the period rolls over and the quota gets refreshed.

Sadly it failed to take the hierarchy into consideration. Share more of the
enqueue/dequeue code with regular task opterations.

Also, some operations like sched_setscheduler() can dequeue/enqueue tasks that
are in throttled runqueues, we should not inadvertly re-enqueue empty runqueues
so check for that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Daniel K. <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:57 +02:00
Peter Zijlstra
7ea56616ba sched: rt-group: fix hierarchy
Don't re-set the entity's runqueue to the wrong rq after we've set it
to the right one.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Daniel K. <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:56 +02:00
Dario Faggioli
49307fd6f7 sched: NULL pointer dereference while setting sched_rt_period_us
When CONFIG_RT_GROUP_SCHED and CONFIG_CGROUP_SCHED are enabled, with:

 echo 10000 > /proc/sys/kernel/sched_rt_period_us

We get this:

 BUG: unable to handle kernel NULL pointer dereference at 0000008c
 [  947.682233] IP: [<c0216b72>] __rt_schedulable+0x12/0x160
 [  947.683123] *pde = 00000000=20
 [  947.683782] Oops: 0000 [#1]
 [  947.684307] Modules linked in:
 [  947.684308]
 [  947.684308] Pid: 2359, comm: bash Not tainted (2.6.26-rc6 #8)
 [  947.684308] EIP: 0060:[<c0216b72>] EFLAGS: 00000246 CPU: 0
 [  947.684308] EIP is at __rt_schedulable+0x12/0x160
 [  947.684308] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000001
 [  947.684308] ESI: c0521db4 EDI: 00000001 EBP: c6cc9f00 ESP: c6cc9ed0
 [  947.684308]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
 [  947.684308] Process bash (pid: 2359, tiÆcc8000 taskÇa54f00=20 task.tiÆcc8000)
 [  947.684308] Stack: c0222790 00000000 080f8c08 c0521db4 c6cc9f00 00000001 00000000 00000000
 [  947.684308]        c6cc9f9c 00000000 c0521db4 00000001 c6cc9f28 c0216d40 00000000 00000000
 [  947.684308]        c6cc9f9c 000f4240 000e7ef0 ffffffff c0521db4 c79dfb60 c6cc9f58 c02af2cc
 [  947.684308] Call Trace:
 [  947.684308]  [<c0222790>] ? do_proc_dointvec_conv+0x0/0x50
 [  947.684308]  [<c0216d40>] ? sched_rt_handler+0x80/0x110
 [  947.684308]  [<c02af2cc>] ? proc_sys_call_handler+0x9c/0xb0
 [  947.684308]  [<c02af2fa>] ? proc_sys_write+0x1a/0x20
 [  947.684308]  [<c0273c36>] ? vfs_write+0x96/0x160
 [  947.684308]  [<c02af2e0>] ? proc_sys_write+0x0/0x20
 [  947.684308]  [<c027423d>] ? sys_write+0x3d/0x70
 [  947.684308]  [<c0202ef5>] ? sysenter_past_esp+0x6a/0x91
 [  947.684308]  =======================
 [  947.684308] Code: 24 04 e8 62 b1 0e 00 89 c7 89 f8 8b 5d f4 8b 75
 f8 8b 7d fc 89 ec 5d c3 90 55 89 e5 57 56 53 83 ec 24 89 45 ec 89 55 e4
 89 4d e8 <8b> b8 8c 00 00 00 85 ff 0f 84 c9 00 00 00 8b 57 24 39 55 e8
 8b
 [  947.684308] EIP: [<c0216b72>] __rt_schedulable+0x12/0x160 SS:ESP  0068:c6cc9ed0

We think the following patch solves the issue.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 09:06:54 +02:00
Paul E. McKenney
d120f65f3a rcu: make rcutorture more vicious: add stutter feature
This patch takes a step towards making rcutorture more brutal by allowing
the test to be automatically periodically paused, with the default being
to run the test for five seconds then pause for five seconds and repeat.
This behavior can be controlled using a new "stutter" module parameter, so
that "stutter=0" gives the old default behavior of running continuously.

Starting and stopping rcutorture more heavily stresses RCU's interaction
with the scheduler, as well as exercising more paths through the
grace-period detection code.

Note that the default to "shuffle_interval" has also been adjusted from
5 seconds to 3 seconds to provide varying overlap with the "stutter"
interval.

I am still unable to provoke the failures that Alexey has been seeing,
even with this patch, but will be doing a few additional things to beef
up rcutorture.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-18 15:06:56 +02:00
Ingo Molnar
5af970a48f rcutorture: WARN_ON_ONCE(1) when detecting an error
this makes it easier for automated tests to pick up such failures.
2008-06-18 10:09:48 +02:00
Rabin Vincent
95e904c7da sched: fix defined-but-unused warning
Fix this warning, which appears with !CONFIG_SMP:
kernel/sched.c:1216: warning: `init_hrtick' defined but not used

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-17 10:36:58 +02:00
Ingo Molnar
766d02786e Merge branch 'linus' into core/rcu 2008-06-16 11:23:36 +02:00
Lai Jiangshan
906d882cac rcu: remove unused field struct rcu_data::rcu_tasklet
Since softirq works for rcu reclaimer, rcu_tasklet is unused now.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-16 10:11:54 +02:00
Masami Hiramatsu
67dddaad5d kprobes: fix error checking of batch registration
Fix error checking routine to catch an error which occurs in first
__register_*probe().

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-12 18:05:40 -07:00
Linus Torvalds
1b3cba8e60 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: 64-bit: fix arithmetics overflow
  sched: fair group: fix overflow(was: fix divide by zero)
  sched: fix TASK_WAKEKILL vs SIGKILL race
2008-06-12 12:55:18 -07:00
Lai Jiangshan
7a232e0350 sched: 64-bit: fix arithmetics overflow
(overflow means weight >= 2^32 here, because inv_weigh = 2^32/weight)

A weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so it will overflow when there are
too many entities.

Although, overflow occurs very rarely, but it break fairness when
it occurs. 64-bits systems have more memory than 32-bit systems
and 64-bit systems can create more process usually, so overflow may
occur more frequently.

This patch guarantees fairness when overflow happens on 64-bit systems.
Thanks to the optimization of compiler, it changes nothing on 32-bit.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-12 14:29:54 +02:00
Lai Jiangshan
2e084786f6 sched: fair group: fix overflow(was: fix divide by zero)
I found a bug which can be reproduced by this way:(linux-2.6.26-rc5, x86-64)
(use 2^32, 2^33, ...., 2^63 as shares value)

# mkdir /dev/cpuctl
# mount -t cgroup -o cpu cpuctl /dev/cpuctl
# cd /dev/cpuctl
# mkdir sub
# echo 0x8000000000000000 > sub/cpu.shares
# echo $$ > sub/tasks
oops here! divide by zero.

This is because do_div() expects the 2th parameter to be 32 bits,
but unsigned long is 64 bits in x86_64.

Peter Zijstra pointed it out that the sane thing to do is limit the
shares value to something smaller instead of using an even more
expensive divide.

Also, I found another bug about "the shares value is too large":

pid1 and pid2 are set affinity to cpu#0
pid1 is attached to cg1 and pid2 is attached to cg2

if cg1/cpu.shares = 1024 cg2/cpu.shares = 2000000000
then pid2 got 100% usage of cpu, and pid1 0%

if cg1/cpu.shares = 1024 cg2/cpu.shares = 20000000000
then pid2 got 0% usage of cpu, and pid1 100%

And a weight of a cfs_rq is the sum of weights of which entities
are queued on this cfs_rq, so the shares value should be limited
to a smaller value.

I think that (1UL << 18) is a good limited value:

1) it's not too large, we can create a lot of group before overflow
2) it's several times the weight value for nice=-19 (not too small)

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-12 14:23:55 +02:00
Oleg Nesterov
16882c1e96 sched: fix TASK_WAKEKILL vs SIGKILL race
schedule() has the special "TASK_INTERRUPTIBLE && signal_pending()" case,
this allows us to do

	current->state = TASK_INTERRUPTIBLE;
	schedule();

without fear to sleep with pending signal.

However, the code like

	current->state = TASK_KILLABLE;
	schedule();

is not right, schedule() doesn't take TASK_WAKEKILL into account. This means
that mutex_lock_killable(), wait_for_completion_killable(), down_killable(),
schedule_timeout_killable() can miss SIGKILL (and btw the second SIGKILL has
no effect).

Introduce the new helper, signal_pending_state(), and change schedule() to
use it. Hopefully it will have more users, that is why the task's state is
passed separately.

Note this "__TASK_STOPPED | __TASK_TRACED" check in signal_pending_state().
This is needed to preserve the current behaviour (ptrace_notify). I hope
this check will be removed soon, but this (afaics good) change needs the
separate discussion.

The fast path is "(state & (INTERRUPTIBLE | WAKEKILL)) + signal_pending(p)",
basically the same that schedule() does now. However, this patch of course
bloats schedule().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-10 11:37:25 +02:00
Linus Torvalds
156a9ea43a Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/chrisw/lsm-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/chrisw/lsm-2.6:
  capabilities: remain source compatible with 32-bit raw legacy capability support.
  LSM: remove stale web site from MAINTAINERS
2008-06-06 11:31:55 -07:00
Lai Jiangshan
37340746a6 cpusets: fix bug when adding nonexistent cpu or mem
Adding a nonexistent cpu to a cpuset will be omitted quietly.  It should
return -EINVAL.

Example: (real_nr_cpus <= 4 < NR_CPUS or cpu#4 was just offline)

# cat cpus
0-1
# /bin/echo 4 > cpus
# /bin/echo $?
0
# cat cpus

#

The same occurs when add a nonexistent mem.
This patch will fix this bug.
And when *buf == "", the check is unneeded.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-06 11:29:11 -07:00
Linus Torvalds
3b5b60b821 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  kgdbts: Use HW breakpoints with CONFIG_DEBUG_RODATA
  kgdb: use common ascii helpers and put_unaligned_be32 helper
2008-06-04 08:08:27 -07:00
Andrew G. Morgan
ca05a99a54 capabilities: remain source compatible with 32-bit raw legacy capability support.
Source code out there hard-codes a notion of what the
_LINUX_CAPABILITY_VERSION #define means in terms of the semantics of the
raw capability system calls capget() and capset().  Its unfortunate, but
true.

Since the confusing header file has been in a released kernel, there is
software that is erroneously using 64-bit capabilities with the semantics
of 32-bit compatibilities.  These recently compiled programs may suffer
corruption of their memory when sys_getcap() overwrites more memory than
they are coded to expect, and the raising of added capabilities when using
sys_capset().

As such, this patch does a number of things to clean up the situation
for all. It

  1. forces the _LINUX_CAPABILITY_VERSION define to always retain its
     legacy value.

  2. adopts a new #define strategy for the kernel's internal
     implementation of the preferred magic.

  3. deprecates v2 capability magic in favor of a new (v3) magic
     number. The functionality of v3 is entirely equivalent to v2,
     the only difference being that the v2 magic causes the kernel
     to log a "deprecated" warning so the admin can find applications
     that may be using v2 inappropriately.

[User space code continues to be encouraged to use the libcap API which
protects the application from details like this.  libcap-2.10 is the first
to support v3 capabilities.]

Fixes issue reported in https://bugzilla.redhat.com/show_bug.cgi?id=447518.
Thanks to Bojan Smojver for the report.

[akpm@linux-foundation.org: s/depreciate/deprecate/g]
[akpm@linux-foundation.org: be robust about put_user size]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Bojan Smojver <bojan@rexursive.com>
Cc: stable@kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
2008-05-31 16:36:16 -07:00
Linus Torvalds
a7f75d3bed 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: re-tune NUMA topologies
  sched: stop wake_affine from causing serious imbalance
  sched: fix sched_clock_cpu()
  revert ("sched: fair-group: SMP-nice for group scheduling")
  sched: cleanup
  show_schedstat(): fix memleak
  sched: unite unlikely pairs in rt_policy() and schedule_debug()
  revert ("sched: fair: weight calculations")
2008-05-29 09:26:17 -07:00
Ingo Molnar
6715930654 Merge commit 'linus/master' into sched-fixes-for-linus 2008-05-29 16:05:05 +02:00
Mike Galbraith
b3137bc8e7 sched: stop wake_affine from causing serious imbalance
Prevent short-running wakers of short-running threads from overloading a single
cpu via wakeup affinity, and wire up disconnected debug option.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:29:20 +02:00
Peter Zijlstra
a381759d6a sched: fix sched_clock_cpu()
Make sched_clock_cpu() return 0 before it has been initialized and avoid
corrupting its state due to doing so.

This fixes the weird printk timestamp jump reported.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2008-05-29 11:29:19 +02:00
Ingo Molnar
6363ca57c7 revert ("sched: fair-group: SMP-nice for group scheduling")
Yanmin Zhang reported:

Comparing with 2.6.25, volanoMark has big regression with kernel 2.6.26-rc1.
It's about 50% on my 8-core stoakley, 16-core tigerton, and Itanium Montecito.

With bisect, I located the following patch:

| 18d95a2832 is first bad commit
| commit 18d95a2832
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Sat Apr 19 19:45:00 2008 +0200
|
|     sched: fair-group: SMP-nice for group scheduling

Revert it so that we get v2.6.25 behavior.

Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:28:57 +02:00
Ingo Molnar
4285f594f8 sched: cleanup
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:25:15 +02:00
Adrian Bunk
c6fba5451a show_schedstat(): fix memleak
The Coverity checker spotted a memleak introduced by commit
39106dcf85 (cpumask: use new cpus_scnprintf
function).

It seems the kfree() got lost between v2 and v3 of this patch...

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: Mike Travis <travis@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:25:15 +02:00
Roel Kluin
3f33a7ce95 sched: unite unlikely pairs in rt_policy() and schedule_debug()
Removes obfuscation and may improve assembly.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:25:14 +02:00
Ingo Molnar
f9305d4a09 revert ("sched: fair: weight calculations")
Yanmin Zhang reported:

Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many
regressions with 2.6.26-rc1:

 1) 8-core stoakley: 28%;
 2) 16-core tigerton: 20%;
 3) Itanium Montvale: 50%.

Bisect located this patch:

| 8f1bc385cf is first bad commit
| commit 8f1bc385cf
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Sat Apr 19 19:45:00 2008 +0200
|
|     sched: fair: weight calculations

Revert it to the 2.6.25 state.

Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-29 11:24:01 +02:00
Harvey Harrison
827e609b45 kgdb: use common ascii helpers and put_unaligned_be32 helper
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2008-05-28 12:49:56 -05:00
Tom Zanussi
a82c53a0e3 splice: fix sendfile() issue with relay
Splice isn't always incrementing the ppos correctly, which broke
relay splice.

Signed-off-by: Tom Zanussi <zanussi@comcast.net>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-05-28 14:49:27 +02:00
Oleg Nesterov
cbaffba12c posix timers: discard SI_TIMER signals on exec
Based on Roland's patch. This approach was suggested by Austin Clements
from the very beginning, and then by Linus.

As Austin pointed out, the execing task can be killed by SI_TIMER signal
because exec flushes the signal handlers, but doesn't discard the pending
signals generated by posix timers. Perhaps not a bug, but people find this
surprising. See http://bugzilla.kernel.org/show_bug.cgi?id=10460

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Austin Clements <amdragon+kernelbugzilla@mit.edu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-26 10:37:07 -07:00
Oleg Nesterov
c8e85b4f4b posix timers: sigqueue_free: don't free sigqueue if it is queued
Currently sigqueue_free() removes sigqueue from list, but doesn't cancel the
pending signal. This is not consistent, the task should either receive the
"full" signal along with siginfo_t, or it shouldn't receive the signal at all.

Change sigqueue_free() to clear SIGQUEUE_PREALLOC but leave sigqueue on list
if it is queued.

This is a user-visible change. If the signal is blocked, it stays queued
after sys_timer_delete() until unblocked with the "stale" si_code/si_value,
and of course it is still counted wrt RLIMIT_SIGPENDING which also limits
the number of posix timers.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Austin Clements <amdragon+kernelbugzilla@mit.edu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-26 10:37:06 -07:00
Cedric Le Goater
5c02b57578 cgroups: remove node_ prefix_from ns subsystem
This is a slight change in the namespace cgroup subsystem api.

The change is that previously when cgroup_clone() was called (currently
only from the unshare path in ns_proxy cgroup, you'd get a new group named
"node_$pid" whereas now you'll get a group named after just your pid.)

The only users who would notice it are those who are using the ns_proxy
cgroup subsystem to auto-create cgroups when namespaces are unshared -
something of an experimental feature, which I think really needs more
complete container/namespace support in order to be useful.  I suspect the
only users are Cedric and Serge, or maybe a few others on
containers@lists.linux-foundation.org.  And in fact it would only be
noticed by the users who make the assumption about how the name is
generated, rather than getting it from the /proc/<pid>/cgroups file for
the process in question.

Whether the change is actually needed or not I'm fairly agnostic on, but I
guess it is more elegant to just use the pid as the new group name rather
than adding a fairly arbitrary "node_" prefix on the front.

[menage@google.com: provided changelog]
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Paul Menage" <menage@google.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-24 09:56:14 -07:00
Shi Weihua
7b26655f62 sys_prctl(): fix return of uninitialized value
If none of the switch cases match, the PR_SET_PDEATHSIG and
PR_SET_DUMPABLE cases of the switch statement will never write to local
variable `error'.

Signed-off-by: Shi Weihua <shiwh@cn.fujitsu.com>
Cc: Andrew G. Morgan <morgan@kernel.org>
Acked-by: "Serge E. Hallyn" <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-24 09:56:13 -07:00
Oleg Nesterov
da7978b034 signals: fix sigqueue_free() vs __exit_signal() race
__exit_signal() does flush_sigqueue(tsk->pending) outside of ->siglock.
This can race with another thread doing sigqueue_free(), we can free the
same SIGQUEUE_PREALLOC sigqueue twice or corrupt the pending->list.

Note that even sys_exit_group() can trigger this race, not only
sys_timer_delete().

Move the callsite of flush_sigqueue(tsk->pending) under ->siglock.

This patch doesn't touch flush_sigqueue(->shared_pending) below, it is
called when there are no other threads which can play with signals, and
sigqueue_free() can't be used outside of our thread group.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-24 09:56:10 -07:00
Christian Borntraeger
3401a61e16 stop_machine: make stop_machine_run more virtualization friendly
On kvm I have seen some rare hangs in stop_machine when I used more guest
cpus than hosts cpus. e.g. 32 guest cpus on 1 host cpu triggered the
hang quite often. I could also reproduce the problem on a 4 way z/VM host with
a 64 way guest.

It turned out that the guest was consuming all available cpus mostly for
spinning on scheduler locks like rq->lock. This is expected as the threads are
calling yield all the time.
The problem is now, that the host scheduling decisings together with the guest
scheduling decisions and spinlocks not being fair managed to create an
interesting scenario similar to a live lock. (Sometimes the hang resolved
itself after some minutes)

Changing stop_machine to yield the cpu to the hypervisor when yielding inside
the guest fixed the problem for me. While I am not completely happy with this
patch, I think it causes no harm and it really improves the situation for me.

I used cpu_relax for yielding to the hypervisor, does that work on all
architectures?

p.s.: If you want to reproduce the problem, cpu hotplug and kprobes use
stop_machine_run and both triggered the problem after some retries.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-23 13:09:34 +10:00
Denis V. Lunev
34e4e2fef4 modules: proper cleanup of kobject without CONFIG_SYSFS
kobject: '<NULL>' (ffffffffa0104050): is not initialized, yet kobject_put() is being called.
------------[ cut here ]------------
WARNING: at /home/den/src/linux-netns26/lib/kobject.c:583 kobject_put+0x53/0x55()
Modules linked in: ipv6 nfsd lockd nfs_acl auth_rpcgss sunrpc exportfs ide_cd_mod cdrom button [last unloaded: pktgen]
comm: rmmod Tainted: G        W 2.6.26-rc3 #585
Call Trace:
  [<ffffffff802359ab>] warn_on_slowpath+0x58/0x7a
  [<ffffffff80236aca>] ? printk+0x67/0x69
  [<ffffffff80236aca>] ? printk+0x67/0x69
  [<ffffffff80324289>] kobject_put+0x53/0x55
  [<ffffffff8025e2ee>] free_module+0x87/0xfa
  [<ffffffff8025fee5>] sys_delete_module+0x178/0x1e1
  [<ffffffff804b1e70>] ? lockdep_sys_exit_thunk+0x35/0x67
  [<ffffffff804b1dff>] ? trace_hardirqs_on_thunk+0x35/0x3a
  [<ffffffff8020c0bb>] system_call_after_swapgs+0x7b/0x80
---[ end trace 8f5aafa7f6406cf8 ]---

mod->mkobj.kobj is not initialized without CONFIG_SYSFS. Do not call
kobject_put in this case.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-23 13:09:33 +10:00
Cyrill Gorcunov
c4ea6fcf5a module loading ELF handling: use SELFMAG instead of numeric constant
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-23 13:09:32 +10:00
Linus Torvalds
16ae527bfa Merge branch 'audit.b51' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current
* 'audit.b51' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current:
  [PATCH] list_for_each_rcu must die: audit
  [patch 1/1] audit_send_reply(): fix error-path memory leak
  [PATCH] open sessionid permissions
2008-05-19 16:38:10 -07:00
Huang Weiyi
247ab1a805 rcu: remove duplicated include in kernel/rcupreempt.c
Removed duplicated include file <linux/rcupdate.h> in kernel/rcupreempt.c.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:03:39 +02:00
Huang Weiyi
e19a98967f rcu: remove duplicated include in kernel/rcupreempt_trace.c
Removed duplicated include file <linux/rcupdate.h> in kernel/rcupreempt_trace.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:03:39 +02:00
Paul E. McKenney
d7c0651390 rcu: fix rcu_try_flip_waitack_needed() to prevent grace-period stall
The comment was correct -- need to make the code match the comment.
Without this patch, if a CPU goes dynticks idle (and stays there forever)
in just the right phase of preemptible-RCU grace-period processing,
grace periods stall.  The offending sequence of events (courtesy
of Promela/spin, at least after I got the liveness criterion coded
correctly...) is as follows:

o	CPU 0 is in dynticks-idle mode.  Its dynticks_progress_counter
	is (say) 10.

o	CPU 0 takes an interrupt, so rcu_irq_enter() increments CPU 0's
	dynticks_progress_counter to 11.

o	CPU 1 is doing RCU grace-period processing in rcu_try_flip_idle(),
	sees rcu_pending(), so invokes dyntick_save_progress_counter(),
	which in turn takes a snapshot of CPU 0's dynticks_progress_counter
	into CPU 0's rcu_dyntick_snapshot -- now set to 11.  CPU 1 then
	updates the RCU grace-period state to rcu_try_flip_waitack().

o	CPU 0 returns from its interrupt, so rcu_irq_exit() increments
	CPU 0's dynticks_progress_counter to 12.

o	CPU 1 later invokes rcu_try_flip_waitack(), which notices that
	CPU 0 has not yet responded, and hence in turn invokes
	rcu_try_flip_waitack_needed().  This function examines the
	state of CPU 0's dynticks_progress_counter and rcu_dyntick_snapshot
	variables, which it copies to curr (== 12) and snap (== 11),
	respectively.

	Because curr!=snap, the first condition fails.

	Because curr-snap is only 1 and snap is odd, the second
	condition fails.

	rcu_try_flip_waitack_needed() therefore incorrectly concludes
	that it must wait for CPU 0 to explicitly acknowledge the
	counter flip.

o	CPU 0 remains forever in dynticks-idle mode, never taking
	any more hardware interrupts or any NMIs, and never running
	any more tasks.  (Of course, -something- will usually eventually
	happen, which might be why we haven't seen this one in the
	wild.  Still should be fixed!)

Therefore the grace period never ends.  Fix is to make the code match
the comment, as shown below.  With this fix, the above scenario
would be satisfied with curr being even, and allow the grace period
to proceed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Josh Triplett <josh@kernel.org>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-19 10:03:38 +02:00