linux-toradex.git/kernel, branch v2.6.27.5 Linux kernel for Apalis and Colibri modules sched_clock: prevent scd->clock from moving backwards 2008-11-07T03:05:50+00:00 Dave Kleikamp shaggy@linux.vnet.ibm.com 2008-10-26T22:20:14+00:00 5e55aa8db085dad1aabb4574c73c23c7ae571e7b commit 5b7dba4ff834259a5623e03a565748704a8fe449 upstream sched_clock: prevent scd->clock from moving backwards When sched_clock_cpu() couples the clocks between two cpus, it may increment scd->clock beyond the GTOD tick window that __update_sched_clock() uses to clamp the clock. A later call to __update_sched_clock() may move the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's monotonic property. This patch ensures that scd->clock will not be set backward. Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
commit 5b7dba4ff834259a5623e03a565748704a8fe449 upstream

sched_clock: prevent scd->clock from moving backwards

When sched_clock_cpu() couples the clocks between two cpus, it may
increment scd->clock beyond the GTOD tick window that __update_sched_clock()
uses to clamp the clock.  A later call to __update_sched_clock() may move
the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's
monotonic property.

This patch ensures that scd->clock will not be set backward.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
sched: disable the hrtick for now 2008-11-07T03:05:50+00:00 Ingo Molnar mingo@elte.hu 2008-10-26T22:21:40+00:00 612f39d5e7baeb0518cfe50d53e37e14c0ca1475 commit 0c4b83da58ec2e96ce9c44c211d6eac5f9dae478 upstream sched: disable the hrtick for now David Miller reported that hrtick update overhead has tripled the wakeup overhead on Sparc64. That is too much - disable the HRTICK feature for now by default, until a faster implementation is found. Reported-by: David Miller <davem@davemloft.net> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
commit 0c4b83da58ec2e96ce9c44c211d6eac5f9dae478 upstream

sched: disable the hrtick for now

David Miller reported that hrtick update overhead has tripled the
wakeup overhead on Sparc64.

That is too much - disable the HRTICK feature for now by default,
until a faster implementation is found.

Reported-by: David Miller <davem@davemloft.net>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
sched: fix the wrong mask_len 2008-10-25T21:32:37+00:00 Miao Xie miaox@cn.fujitsu.com 2008-10-23T16:50:03+00:00 919e14cd03504d00e4ba13933ac229f7eca21444 commit c851c8676bd7ae456e9b3af8e6bb2c434eddcc75 upstream If NR_CPUS isn't a multiple of 32, we get a truncated string of sched domains by catting /proc/schedstat. This is caused by the wrong mask_len. This patch fixes it. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
commit c851c8676bd7ae456e9b3af8e6bb2c434eddcc75 upstream

If NR_CPUS isn't a multiple of 32, we get a truncated string of sched
domains by catting /proc/schedstat. This is caused by the wrong mask_len.

This patch fixes it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
modules: fix module "notes" kobject leak 2008-10-22T21:20:57+00:00 Alexey Dobriyan adobriyan@gmail.com 2008-10-16T22:05:10+00:00 0b84283d642d6865e15ddad62dd2f1a092812f5a commit e94320939f44e0cbaccc3f259a5778abced4949c upstream Fix "notes" kobject leak It happens every rmmod if KALLSYMS=y and SYSFS=y. # modprobe foo kobject: 'foo' (ffffffffa00743d0): kobject_add_internal: parent: 'module', set: 'module' kobject: 'holders' (ffff88017e7c5770): kobject_add_internal: parent: 'foo', set: '<NULL>' kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo' kobject: 'notes' (ffff88017fa9b668): kobject_add_internal: parent: 'foo', set: '<NULL>' ^^^^^ # rmmod foo kobject: 'holders' (ffff88017e7c5770): kobject_cleanup kobject: 'holders' (ffff88017e7c5770): auto cleanup kobject_del kobject: 'holders' (ffff88017e7c5770): calling ktype release kobject: (ffff88017e7c5770): dynamic_kobj_release kobject: 'holders': free name kobject: 'foo' (ffffffffa00743d0): kobject_cleanup kobject: 'foo' (ffffffffa00743d0): does not have a release() function, it is broken and must be fixed. kobject: 'foo' (ffffffffa00743d0): auto cleanup 'remove' event kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo' kobject: 'foo' (ffffffffa00743d0): auto cleanup kobject_del kobject: 'foo': free name [whooops] Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
commit e94320939f44e0cbaccc3f259a5778abced4949c upstream

Fix "notes" kobject leak

It happens every rmmod if KALLSYMS=y and SYSFS=y.

	# modprobe foo

kobject: 'foo' (ffffffffa00743d0): kobject_add_internal: parent: 'module', set: 'module'
kobject: 'holders' (ffff88017e7c5770): kobject_add_internal: parent: 'foo', set: '<NULL>'
kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env
kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo'
kobject: 'notes' (ffff88017fa9b668): kobject_add_internal: parent: 'foo', set: '<NULL>'
	  ^^^^^

	# rmmod foo

kobject: 'holders' (ffff88017e7c5770): kobject_cleanup
kobject: 'holders' (ffff88017e7c5770): auto cleanup kobject_del
kobject: 'holders' (ffff88017e7c5770): calling ktype release
kobject: (ffff88017e7c5770): dynamic_kobj_release
kobject: 'holders': free name
kobject: 'foo' (ffffffffa00743d0): kobject_cleanup
kobject: 'foo' (ffffffffa00743d0): does not have a release() function, it is broken and must be fixed.
kobject: 'foo' (ffffffffa00743d0): auto cleanup 'remove' event
kobject: 'foo' (ffffffffa00743d0): kobject_uevent_env
kobject: 'foo' (ffffffffa00743d0): fill_kobj_path: path = '/module/foo'
kobject: 'foo' (ffffffffa00743d0): auto cleanup kobject_del
kobject: 'foo': free name

	[whooops]

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
sched_rt.c: resch needed in rt_rq_enqueue() for the root rt_rq 2008-10-18T17:49:10+00:00 Dario Faggioli raistlin@linux.it 2008-10-10T20:15:02+00:00 d49d50a98a807e9322bc287e5da26d70168cd4c0 commit f6121f4f8708195e88cbdf8dd8d171b226b3f858 upstream While working on the new version of the code for SCHED_SPORADIC I noticed something strange in the present throttling mechanism. More specifically in the throttling timer handler in sched_rt.c (do_sched_rt_period_timer()) and in rt_rq_enqueue(). The problem is that, when unthrottling a runqueue, rt_rq_enqueue() only asks for rescheduling if the runqueue has a sched_entity associated to it (i.e., rt_rq->rt_se != NULL). Now, if the runqueue is the root rq (which has a rt_se = NULL) rescheduling does not take place, and it is delayed to some undefined instant in the future. This imply some random bandwidth usage by the RT tasks under throttling. For instance, setting rt_runtime_us/rt_period_us = 950ms/1000ms an RT task will get less than 95%. In our tests we got something varying between 70% to 95%. Using smaller time values, e.g., 95ms/100ms, things are even worse, and I can see values also going down to 20-25%!! The tests we performed are simply running 'yes' as a SCHED_FIFO task, and checking the CPU usage with top, but we can investigate thoroughly if you think it is needed. Things go much better, for us, with the attached patch... Don't know if it is the best approach, but it solved the issue for us. Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
commit f6121f4f8708195e88cbdf8dd8d171b226b3f858 upstream

While working on the new version of the code for SCHED_SPORADIC I
noticed something strange in the present throttling mechanism. More
specifically in the throttling timer handler in sched_rt.c
(do_sched_rt_period_timer()) and in rt_rq_enqueue().

The problem is that, when unthrottling a runqueue, rt_rq_enqueue() only
asks for rescheduling if the runqueue has a sched_entity associated to
it (i.e., rt_rq->rt_se != NULL).
Now, if the runqueue is the root rq (which has a rt_se = NULL)
rescheduling does not take place, and it is delayed to some undefined
instant in the future.

This imply some random bandwidth usage by the RT tasks under throttling.
For instance, setting rt_runtime_us/rt_period_us = 950ms/1000ms an RT
task will get less than 95%. In our tests we got something varying
between 70% to 95%.
Using smaller time values, e.g., 95ms/100ms, things are even worse, and
I can see values also going down to 20-25%!!

The tests we performed are simply running 'yes' as a SCHED_FIFO task,
and checking the CPU usage with top, but we can investigate thoroughly
if you think it is needed.

Things go much better, for us, with the attached patch... Don't know if
it is the best approach, but it solved the issue for us.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
disable CONFIG_DYNAMIC_FTRACE due to possible memory corruption on module unload 2008-10-15T23:02:33+00:00 Steven Rostedt rostedt@goodmis.org 2008-10-15T22:21:44+00:00 d23d43386311fde5f11e06c16d4185e94a8d6d06 While debugging the e1000e corruption bug with Intel, we discovered today that the dynamic ftrace code in mainline is the likely source of this bug. For the stable kernel we are providing the only viable fix patch: labeling CONFIG_DYNAMIC_FTRACE as broken. (see the patch below) We will follow up with a backport patch that contains the fixes. But since the fixes are not a one liner, the safest approach for now is to disable the code in question. The cause of the bug is due to the way the current code in mainline handles dynamic ftrace. When dynamic ftrace is turned on, it also turns on CONFIG_FTRACE which enables the -pg config in gcc that places a call to mcount at every function call. With just CONFIG_FTRACE this causes a noticeable overhead. CONFIG_DYNAMIC_FTRACE works to ease this overhead by dynamically updating the mcount call sites into nops. The problem arises when we trace functions and modules are unloaded. The first time a function is called, it will call mcount and the mcount call will call ftrace_record_ip. This records the calling site and stores it in a preallocated hash table. Later on a daemon will wake up and call kstop_machine and convert any mcount callers into nops. The evolution of this code first tried to do this without the kstop_machine and used cmpxchg to update the callers as they were called. But I was informed that this is dangerous to do on SMP machines if another CPU is running that same code. The solution was to do this with kstop_machine. We still used cmpxchg to test if the code that we are modifying is indeed code that we expect to be before updating it - as a final line of defense. But on 32bit machines, ioremapped memory and modules share the same address space. When a module would load its code into memory and execute some code, that would register the function. On module unload, ftrace incorrectly did not zap these functions from its hash (this was the bug). The cmpxchg could have saved us in most cases (via luck) - but with ioremap-ed memory that was exactly the wrong thing to do - the results of cmpxchg on device memory are undefined. (and will likely result in a write) The pending .28 ftrace tree does not have this bug anymore, as a general push towards more robustness of code patching, this is done differently: we do not use cmpxchg and we do a WARN_ON and turn the tracer off if anything deviates from its expected state. Furthermore, patch sites are statically identified during build time so there's no runtime discovery of dynamic code areas anymore, and no room for code unmaps to cause the hash to become out of date. We believe the fragility of dynamic patching has been sufficiently addressed in the development code via the static patching method, but further suggestions to make it more robust are welcome. Signed-off-by: Steven Rostedt <srostedt@goodmis.org> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> 
While debugging the e1000e corruption bug with Intel, we discovered
today that the dynamic ftrace code in mainline is the likely source of
this bug.

For the stable kernel we are providing the only viable fix patch: labeling
CONFIG_DYNAMIC_FTRACE as broken. (see the patch below)

We will follow up with a backport patch that contains the fixes. But since
the fixes are not a one liner, the safest approach for now is to
disable the code in question.

The cause of the bug is due to the way the current code in mainline
handles dynamic ftrace.  When dynamic ftrace is turned on, it also
turns on CONFIG_FTRACE which enables the -pg config in gcc that places
a call to mcount at every function call. With just CONFIG_FTRACE this
causes a noticeable overhead.  CONFIG_DYNAMIC_FTRACE works to ease this
overhead by dynamically updating the mcount call sites into nops.

The problem arises when we trace functions and modules are unloaded.
The first time a function is called, it will call mcount and the mcount
call will call ftrace_record_ip. This records the calling site and
stores it in a preallocated hash table. Later on a daemon will
wake up and call kstop_machine and convert any mcount callers into
nops.

The evolution of this code first tried to do this without the kstop_machine
and used cmpxchg to update the callers as they were called. But I
was informed that this is dangerous to do on SMP machines if another
CPU is running that same code. The solution was to do this with
kstop_machine.

We still used cmpxchg to test if the code that we are modifying is
indeed code that we expect to be before updating it - as a final
line of defense.

But on 32bit machines, ioremapped memory and modules share the same
address space. When a module would load its code into memory and execute
some code, that would register the function.

On module unload, ftrace incorrectly did not zap these functions from
its hash (this was the bug). The cmpxchg could have saved us in most
cases (via luck) - but with ioremap-ed memory that was exactly the wrong
thing to do - the results of cmpxchg on device memory are undefined.
(and will likely result in a write)

The pending .28 ftrace tree does not have this bug anymore, as a general push
towards more robustness of code patching, this is done differently: we do not
use cmpxchg and we do a WARN_ON and turn the tracer off if anything deviates
from its expected state. Furthermore, patch sites are statically identified
during build time so there's no runtime discovery of dynamic code areas
anymore, and no room for code unmaps to cause the hash to become out of date.

We believe the fragility of dynamic patching has been sufficiently
addressed in the development code via the static patching method, but further
suggestions to make it more robust are welcome.

Signed-off-by: Steven Rostedt <srostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
kgdb: call touch_softlockup_watchdog on resume 2008-10-06T18:50:59+00:00 Jason Wessel jason.wessel@windriver.com 2008-10-06T18:50:59+00:00 cc1e0f4f7ad95a9eb81e1904cb16068af226180d The softlockup watchdog needs to be touched when resuming the from the kgdb stopped state to avoid the printk that a CPU is stuck if the debugger was active for longer than the softlockup threshold. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> 
The softlockup watchdog needs to be touched when resuming the from the
kgdb stopped state to avoid the printk that a CPU is stuck if the
debugger was active for longer than the softlockup threshold.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
clockevents: check broadcast tick device not the clock events device 2008-10-04T08:51:07+00:00 Thomas Gleixner tglx@linutronix.de 2008-10-04T08:51:07+00:00 07454bfff151d2465ada809bbaddf3548cc1097c Impact: jiffies increment too fast. Hugh Dickins noted that with NOHZ=n and HIGHRES=n jiffies get incremented too fast. The reason is a wrong check in the broadcast enter/exit code, which keeps the local apic timer in periodic mode when the switch happens. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Impact: jiffies increment too fast.

Hugh Dickins noted that with NOHZ=n and HIGHRES=n jiffies get
incremented too fast. The reason is a wrong check in the broadcast
enter/exit code, which keeps the local apic timer in periodic mode
when the switch happens.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
fix error-path NULL deref in alloc_posix_timer() 2008-10-02T22:53:13+00:00 Dan Carpenter error27@gmail.com 2008-10-02T21:50:14+00:00 aa94fbd5ccd840c8ab26d02439ec799b03a72547 Found by static checker (http://repo.or.cz/w/smatch.git). Signed-off-by: Dan Carpenter <error27@gmail.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Found by static checker (http://repo.or.cz/w/smatch.git).

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-09-30T15:39:28+00:00 Linus Torvalds torvalds@linux-foundation.org 2008-09-30T15:39:18+00:00 cf4b0b2c9520728e170f7a3061e24dbae0b56ed4 * 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: hrtimer: prevent migration of per CPU hrtimers hrtimer: mark migration state hrtimer: fix migration of CB_IRQSAFE_NO_SOFTIRQ hrtimers hrtimer: migrate pending list on cpu offline Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: prevent migration of per CPU hrtimers
  hrtimer: mark migration state
  hrtimer: fix migration of CB_IRQSAFE_NO_SOFTIRQ hrtimers
  hrtimer: migrate pending list on cpu offline

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>