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This patch implements a Refcount + Waitqueue based model for
cpu-hotplug.
Now, a thread which wants to prevent cpu-hotplug, will bump up a global
refcount and the thread which wants to perform a cpu-hotplug operation
will block till the global refcount goes to zero.
The readers, if any, during an ongoing cpu-hotplug operation are blocked
until the cpu-hotplug operation is over.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Paul Jackson <pj@sgi.com> [For !CONFIG_HOTPLUG_CPU ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The current load balancing scheme isn't good enough for precise
group fairness.
For example: on a 8-cpu system, I created 3 groups as under:
a = 8 tasks (cpu.shares = 1024)
b = 4 tasks (cpu.shares = 1024)
c = 3 tasks (cpu.shares = 1024)
a, b and c are task groups that have equal weight. We would expect each
of the groups to receive 33.33% of cpu bandwidth under a fair scheduler.
This is what I get with the latest scheduler git tree:
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------------------
Col1 | Col2 | Col3 | Col4
------|---------|-------|-------------------------------------------------------
a | 277.676 | 57.8% | 54.1% 54.1% 54.1% 54.2% 56.7% 62.2% 62.8% 64.5%
b | 116.108 | 24.2% | 47.4% 48.1% 48.7% 49.3%
c | 86.326 | 18.0% | 47.5% 47.9% 48.5%
--------------------------------------------------------------------------------
Explanation of o/p:
Col1 -> Group name
Col2 -> Cumulative execution time (in seconds) received by all tasks of that
group in a 60sec window across 8 cpus
Col3 -> CPU bandwidth received by the group in the 60sec window, expressed in
percentage. Col3 data is derived as:
Col3 = 100 * Col2 / (NR_CPUS * 60)
Col4 -> CPU bandwidth received by each individual task of the group.
Col4 = 100 * cpu_time_recd_by_task / 60
[I can share the test case that produces a similar o/p if reqd]
The deviation from desired group fairness is as below:
a = +24.47%
b = -9.13%
c = -15.33%
which is quite high.
After the patch below is applied, here are the results:
--------------------------------------------------------------------------------
Col1 | Col2 | Col3 | Col4
------|---------|-------|-------------------------------------------------------
a | 163.112 | 34.0% | 33.2% 33.4% 33.5% 33.5% 33.7% 34.4% 34.8% 35.3%
b | 156.220 | 32.5% | 63.3% 64.5% 66.1% 66.5%
c | 160.653 | 33.5% | 85.8% 90.6% 91.4%
--------------------------------------------------------------------------------
Deviation from desired group fairness is as below:
a = +0.67%
b = -0.83%
c = +0.17%
which is far better IMO. Most of other runs have yielded a deviation within
+-2% at the most, which is good.
Why do we see bad (group) fairness with current scheuler?
=========================================================
Currently cpu's weight is just the summation of individual task weights.
This can yield incorrect results. For ex: consider three groups as below
on a 2-cpu system:
CPU0 CPU1
---------------------------
A (10) B(5)
C(5)
---------------------------
Group A has 10 tasks, all on CPU0, Group B and C have 5 tasks each all
of which are on CPU1. Each task has the same weight (NICE_0_LOAD =
1024).
The current scheme would yield a cpu weight of 10240 (10*1024) for each cpu and
the load balancer will think both CPUs are perfectly balanced and won't
move around any tasks. This, however, would yield this bandwidth:
A = 50%
B = 25%
C = 25%
which is not the desired result.
What's changing in the patch?
=============================
- How cpu weights are calculated when CONFIF_FAIR_GROUP_SCHED is
defined (see below)
- API Change
- Two tunables introduced in sysfs (under SCHED_DEBUG) to
control the frequency at which the load balance monitor
thread runs.
The basic change made in this patch is how cpu weight (rq->load.weight) is
calculated. Its now calculated as the summation of group weights on a cpu,
rather than summation of task weights. Weight exerted by a group on a
cpu is dependent on the shares allocated to it and also the number of
tasks the group has on that cpu compared to the total number of
(runnable) tasks the group has in the system.
Let,
W(K,i) = Weight of group K on cpu i
T(K,i) = Task load present in group K's cfs_rq on cpu i
T(K) = Total task load of group K across various cpus
S(K) = Shares allocated to group K
NRCPUS = Number of online cpus in the scheduler domain to
which group K is assigned.
Then,
W(K,i) = S(K) * NRCPUS * T(K,i) / T(K)
A load balance monitor thread is created at bootup, which periodically
runs and adjusts group's weight on each cpu. To avoid its overhead, two
min/max tunables are introduced (under SCHED_DEBUG) to control the rate
at which it runs.
Fixes from: Peter Zijlstra <a.p.zijlstra@chello.nl>
- don't start the load_balance_monitor when there is only a single cpu.
- rename the kthread because its currently longer than TASK_COMM_LEN
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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doms_cur[] array represents various scheduling domains which are
mutually exclusive. Currently cpusets code can modify this array (by
calling partition_sched_domains()) as a result of user modifying
sched_load_balance flag for various cpusets.
This patch introduces a mutex and corresponding API (only when
CONFIG_FAIR_GROUP_SCHED is defined) which allows a reader to safely read
the doms_cur[] array w/o worrying abt concurrent modifications to the
array.
The fair group scheduler code (introduced in next patch of this series)
makes use of this mutex to walk thr' doms_cur[] array while rebalancing
shares of task groups across cpus.
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch changes how the cpu load exerted by fair_sched_class tasks
is calculated. Load exerted by fair_sched_class tasks on a cpu is now
a summation of the group weights, rather than summation of task weights.
Weight exerted by a group on a cpu is dependent on the shares allocated
to it.
This version of patch has a minor impact on code size, but should have
no runtime/functional impact for !CONFIG_FAIR_GROUP_SCHED.
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Minor bug fixes for the group scheduler:
- Use a mutex to serialize add/remove of task groups and also when
changing shares of a task group. Use the same mutex when printing
cfs_rq debugging stats for various task groups.
- Use list_for_each_entry_rcu in for_each_leaf_cfs_rq macro (when
walking task group list)
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Minor cleanups:
- Fix coding style
- remove obsolete comment
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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printk_clock() is obsolete - it has been replaced with cpu_clock().
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Stefano Brivio reported weird printk timestamp behavior during
CPU frequency changes:
http://bugzilla.kernel.org/show_bug.cgi?id=9475
fix CONFIG_PRINT_TIME's reliance on sched_clock() and use cpu_clock()
instead.
Reported-and-bisected-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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make printk more robust by allowing recursion only if there's a crash
going on. Also add recursion detection.
I've tested it with an artificially injected printk recursion - instead
of a lockup or spontaneous reboot or other crash, the output was a well
controlled:
[ 41.057335] SysRq : <2>BUG: recent printk recursion!
[ 41.057335] loglevel0-8 reBoot Crashdump show-all-locks(D) tErm Full kIll saK showMem Nice powerOff showPc show-all-timers(Q) unRaw Sync showTasks Unmount shoW-blocked-tasks
also do all this printk-debug logic with irqs disabled.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Nick Piggin <npiggin@suse.de>
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* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hskinnemoen/avr32-2.6:
[AVR32] extint: Set initial irq type to low level
[AVR32] extint: change set_irq_type() handling
[AVR32] NMI debugging
[AVR32] constify function pointer tables
[AVR32] ATNGW100: Update defconfig
[AVR32] ATSTK1002: Update defconfig
[AVR32] Kconfig: Choose daughterboard instead of CPU
[AVR32] Add support for ATSTK1003 and ATSTK1004
[AVR32] Clean up external DAC setup code
[AVR32] ATSTK1000: Move gpio-leds setup to setup.c
[AVR32] Add support for AT32AP7001 and AT32AP7002
[AVR32] Provide more CPU information in /proc/cpuinfo and dmesg
[AVR32] Oprofile support
[AVR32] Include instrumentation menu
Disable VGA text console for AVR32 architecture
[AVR32] Enable debugging only when needed
ptrace: Call arch_ptrace_attach() when request=PTRACE_TRACEME
[AVR32] Remove redundant try_to_freeze() call from do_signal()
[AVR32] Drop GFP_COMP for DMA memory allocations
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arch_ptrace_attach() is a hook that allows the architecture to do
book-keeping after a ptrace attach. This patch adds a call to this
hook when handling a PTRACE_TRACEME request as well.
Currently only one architecture, m32r, implements this hook. When
called, it initializes a number of debug trap slots in the ptraced
task's thread struct, and it looks to me like this is the right thing
to do after a PTRACE_TRACEME request as well, not only after
PTRACE_ATTACH. Please correct me if I'm wrong.
I want to use this hook on AVR32 to turn the debugging hardware on
when a process is actually being debugged and keep it off otherwise.
To be able to do this, I need to intercept PTRACE_TRACEME and
PTRACE_ATTACH, as well as PTRACE_DETACH and thread exit. The latter
two can be handled by existing hooks.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
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All kobjects require a dynamically allocated name now. We no longer
need to keep track if the name is statically assigned, we can just
unconditionally free() all kobject names on cleanup.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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There is no need for kobject_unregister() anymore, thanks to Kay's
kobject cleanup changes, so replace all instances of it with
kobject_put().
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Now that kobjects properly clean up their name structures, no matter if
they have a release function or not, we can drop this empty module
kobject release function too (it was needed prior to this because of the
way we handled static kobject names, we based the fact that if a release
function was present, then we could safely free the name string, now we
are more smart about things and only free names we have previously set.)
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This converts the code to use the new kobject functions, cleaning up the
logic in doing so.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Sysfs symlinks now require fully registered kobjects as a target,
otherwise the call to create a symlink will fail. Here we register
the kobject before we request the symlink in the holders directory.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Tejun Heo <teheo@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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The module driver specific code should belong in the driver core, not in
the kernel/ directory. So move this code. This is done in preparation
for some struct device_driver rework that should be confined to the
driver core code only.
This also lets us keep from exporting these functions, as no external
code should ever be calling it.
Thanks to Andrew Morton for the !CONFIG_MODULES fix.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This converts the code to use the new kobject functions, cleaning up the
logic in doing so.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This converts the code to use the new kobject functions, cleaning up the
logic in doing so.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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/sys/power should not be a kset, that's overkill. This patch renames it
to power_kset and fixes up all usages of it in the tree.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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kernel_kset does not need to be a kset, but a much simpler kobject now
that we have kobj_attributes.
We also rename kernel_kset to kernel_kobj to catch all users of this
symbol with a build error instead of an easy-to-ignore build warning.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Clean up the use of ksets and kobjects. Kobjects are instances of
objects (like struct user_info), ksets are collections of objects of a
similar type (like the uids directory containing the user_info directories).
So, use kobjects for the user_info directories, and a kset for the "uids"
directory.
On object cleanup, the final kobject_put() was missing.
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Switch all dynamically created ksets, that export simple attributes,
to kobj_attribute from subsys_attribute. Struct subsys_attribute will
be removed.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Mike Halcrow <mhalcrow@us.ibm.com>
Cc: Phillip Hellewell <phillip@hellewell.homeip.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Dynamically create the kset instead of declaring it statically. We also
rename power_subsys to power_kset to catch all users of the variable and
we properly export it so that people don't have to guess that it really
is present in the system.
The pseries code is wierd, why is it createing /sys/power if CONFIG_PM
is disabled? Oh well, stupid big boxes ignoring config options...
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Dynamically create the kset instead of declaring it statically. We also
rename module_subsys to module_kset to catch all users of the variable.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Dynamically create the kset instead of declaring it statically. We also
rename kernel_subsys to kernel_kset to catch all users of this symbol
with a build error instead of an easy-to-ignore build warning.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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kobject_create_and_add is the same as kobject_add_dir, so drop
kobject_add_dir.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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We don't need a "default" ktype for a kset. We should set this
explicitly every time for each kset. This change is needed so that we
can make ksets dynamic, and cleans up one of the odd, undocumented
assumption that the kset/kobject/ktype model has.
This patch is based on a lot of help from Kay Sievers.
Nasty bug in the block code was found by Dave Young
<hidave.darkstar@gmail.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Michael Wu noticed in his lkml post at
http://marc.info/?l=linux-kernel&m=119396182726091&w=2
that certain wireless drivers ended up having their name in module
memory, which would then crash the kernel on module unload.
The patch he proposed was a bit clumsy in that it increased the size of
a lockdep entry significantly; the patch below tries another approach,
it checks, on module teardown, if the name of a class is in module space
and then zaps the class. This is very similar to what we already do
with keys that are in module space.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched:
sched: group scheduler, set uid share fix
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rcu_online_cpu() should be __cpuinit instead of __devinit.
WARNING: vmlinux.o(.text+0x4b6d5): Section mismatch: reference to .init.text: (between 'rcu_cpu_notify' and 'wakeme_after_rcu')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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setting cpu share to 1 causes hangs, as reported in:
http://bugzilla.kernel.org/show_bug.cgi?id=9779
as the default share is 1024, the values of 0 and 1 can indeed
cause problems. Limit it to 2 or higher values.
These values can only be set by the root user - but still it
makes sense to protect against nonsensical values.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The caller is __cpuinit.
Also, this code block and its caller are inside #ifdef CONFIG_HOTPLUG_CPU
blocks, so this code should reflect that config symbol's usage.
WARNING: vmlinux.o(.text+0x4252f): Section mismatch: reference to .init.text: (between 'timer_cpu_notify' and 'msleep')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@akpm@linux-foundation.org>
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Fix section mismatch in hrtimer.c:
WARNING: vmlinux.o(.text+0x50c61): Section mismatch: reference to .init.text: (between 'hrtimer_cpu_notify' and 'down_read_trylock')
Noticed by Johannes Berg and confirmed by Sam Ravnborg.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@akpm@linux-foundation.org>
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call_usermodehelper_exec() has an exit path that can leave the
helper_lock() call at the top of the routine unbalanced. The attached
patch fixes this issue.
Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Dave Young reported warnings from lockdep that the workqueue API
can sometimes try to register lockdep classes with the same key
but different names. This is not permitted in lockdep.
Unfortunately, I was unaware of that restriction when I wrote
the code to debug workqueue problems with lockdep and used the
workqueue name as the lockdep class name. This can obviously
lead to the problem if the workqueue name is dynamic.
This patch solves the problem by always using a constant name
for the workqueue's lockdep class, namely either the constant
name that was passed in or a string consisting of the variable
name.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Lockdep, during self-test (when it was simulating double unlocks) was
sometimes unconditionally unlocking a spinlock when it had not been
locked. This won't work for ticket locks.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Kyle McMartin reports sysrq_timer_list_show() can hit the module mutex
from hard interrupt context. These paths don't need to though, since we
long ago changed all the module list manipulation to occur via
stop_machine().
Disabling preemption is enough.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6:
pnpacpi: print resource shortage message only once
PM: ACPI and APM must not be enabled at the same time
ACPI: apply quirk_ich6_lpc_acpi to more ICH8 and ICH9
ACPICA: fix acpi_serialize hang regression
ACPI : Not register gsi for PCI IDE controller in legacy mode
ACPI: Reintroduce run time configurable max_cstate for !CPU_IDLE case
ACPI: Make sysfs interface in ACPI power optional.
ACPI: EC: Enable boot EC before bus_scan
increase PNP_MAX_PORT to 40 from 24
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task_ppid_nr_ns is called in three places. One of these should never
have called it. In the other two, using it broke the existing
semantics. This was presumably accidental. If the function had not
been there, it would have been much more obvious to the eye that those
patches were changing the behavior. We don't need this function.
In task_state, the pid of the ptracer is not the ppid of the ptracer.
In do_task_stat, ppid is the tgid of the real_parent, not its pid.
I also moved the call outside of lock_task_sighand, since it doesn't
need it.
In sys_getppid, ppid is the tgid of the real_parent, not its pid.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ACPI and APM used "pm_active" to guarantee that
they would not be simultaneously active.
But pm_active was recently moved under CONFIG_PM_LEGACY,
so that without CONFIG_PM_LEGACY, pm_active became a NOP --
allowing ACPI and APM to both be simultaneously enabled.
This caused unpredictable results, including boot hangs.
Further, the code under CONFIG_PM_LEGACY is scheduled
for removal.
So replace pm_active with pm_flags.
pm_flags depends only on CONFIG_PM,
which is present for both CONFIG_APM and CONFIG_ACPI.
http://bugzilla.kernel.org/show_bug.cgi?id=9194
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
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The show_task function invoked by sysrq-t et al displays the
pid and parent's pid of each task. It seems more useful to
show the actual process hierarchy here than who is using
ptrace on each process.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Roland Westrelin did a great analysis of a long standing thinko in the
return path of futex_lock_pi.
While we fixed the lock steal case long ago, which was easy to trigger,
we never had a test case which exposed this problem and stupidly never
thought about the reverse lock stealing scenario and the return to user
space with a stale state.
When a blocked tasks returns from rt_mutex_timed_locked without holding
the rt_mutex (due to a signal or timeout) and at the same time the task
holding the futex is releasing the futex and assigning the ownership of
the futex to the returning task, then it might happen that a third task
acquires the rt_mutex before the final rt_mutex_trylock() of the
returning task happens under the futex hash bucket lock. The returning
task returns to user space with ETIMEOUT or EINTR, but the user space
futex value is assigned to this task. The task which acquired the
rt_mutex fixes the user space futex value right after the hash bucket
lock has been released by the returning task, but for a short period of
time the user space value is wrong.
Detailed description is available at:
https://bugzilla.redhat.com/show_bug.cgi?id=400541
The fix for this is the same as we do when the rt_mutex was acquired by
a higher priority task via lock stealing from the designated new owner.
In that case we already fix the user space value and the internal
pi_state up before we return. This mechanism can be used to fixup the
above corner case as well. When the returning task, which failed to
acquire the rt_mutex, notices that it is the designated owner of the
futex, then it fixes up the stale user space value and the pi_state,
before returning to user space. This happens with the futex hash bucket
lock held, so the task which acquired the rt_mutex is guaranteed to be
blocked on the hash bucket lock. We can access the rt_mutex owner, which
gives us the pid of the new owner, safely here as the owner is not able
to modify (release) it while waiting on the hash bucket lock.
Rename the "curr" argument of fixup_pi_state_owner() to "newowner" to
avoid confusion with current and add the check for the stale state into
the failure path of rt_mutex_trylock() in the return path of
unlock_futex_pi(). If the situation is detected use
fixup_pi_state_owner() to assign everything to the owner of the
rt_mutex.
Pointed-out-and-tested-by: Roland Westrelin <roland.westrelin@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch adds the array length of "free_area.free_list" to the vmcoreinfo
data so that makedumpfile (dump filtering command) can exclude all free pages
in linux-2.6.24.
makedumpfile creates a small dumpfile by excluding unnecessary pages for the
analysis. To distinguish unnecessary pages, makedumpfile gets the vmcoreinfo
data which has the minimum debugging information only for dump filtering.
In 2.6.24-rc1 or later, the free_area.free_list is an array which has one list
for each migrate types instead of a single list. makedumpfile needs the array
length of "free_area.free_list" and the vmcoreinfo data should contain it.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Tested-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Simon Horman <horms@verge.net.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The ac_ppid field reported in process accounting records
should match what getppid() would have returned to that
process, regardless of whether a debugger is attached.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched:
sched: fix gcc warnings
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The previous commit missed one use of "may_attach()" that had been
renamed to __ptrace_may_attach(). Tssk, tssk, Al.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Contents of /proc/*/maps is sensitive and may become sensitive after
open() (e.g. if target originally shares our ->mm and later does exec
on suid-root binary).
Check at read() (actually, ->start() of iterator) time that mm_struct
we'd grabbed and locked is
- still the ->mm of target
- equal to reader's ->mm or the target is ptracable by reader.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Meelis Roos reported these warnings on sparc64:
CC kernel/sched.o
In file included from kernel/sched.c:879:
kernel/sched_debug.c: In function 'nsec_high':
kernel/sched_debug.c:38: warning: comparison of distinct pointer types lacks a cast
the debug check in do_div() is over-eager here, because the long long
is always positive in these places. Mark this by casting them to
unsigned long long.
no change in code output:
text data bss dec hex filename
51471 6582 376 58429 e43d sched.o.before
51471 6582 376 58429 e43d sched.o.after
md5:
7f7729c111f185bf3ccea4d542abc049 sched.o.before.asm
7f7729c111f185bf3ccea4d542abc049 sched.o.after.asm
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Gautham R Shenoy
Srivatsa Vaddagiri
Ingo Molnar
Linus Torvalds
Haavard Skinnemoen
Kay Sievers
Greg Kroah-Hartman
Arjan van de Ven
Linus Torvalds
Randy Dunlap
Nigel Cunningham
Johannes Berg
Nick Piggin
Rusty Russell
Roland McGrath
Len Brown
Thomas Gleixner
Ken'ichi Ohmichi
Al Viro