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A segmentation fault can occur in kimage_add_entry in kexec.c when loading
a kernel image into memory. The fault occurs because a page is requested
by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the function may
actually return a page with gfp_mask GFP_HIGHUSER. The high mem page is
returned because it was swapped with the kernel page due to the kernel
page being a page that will shortly be copied to.
This patch ensures that kimage_alloc_page returns a page that was created
with the correct gfp flags.
I have verified the change and fixed the whitespace damage of the original
patch. Jonathan did a great job of tracking this down after he hit the
problem. -- Eric
Signed-off-by: Jonathan Steel <jon.steel@esentire.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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 deadlock in setting scheduler parameter to zero
sched: fix 2.6.27-rc5 couldn't boot on tulsa machine randomly
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
clockevents: make device shutdown robust
clocksource, acpi_pm.c: fix check for monotonicity
clockevents: remove WARN_ON which was used to gather information
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The device shut down does not cleanup the next_event variable of the
clock event device. So when the device is reactivated the possible
stale next_event value can prevent the device to be reprogrammed as it
claims to wait on a event already.
This is the root cause of the resurfacing suspend/resume problem,
where systems need key press to come back to life.
Fix this by setting next_event to KTIME_MAX when the device is shut
down. Use a separate function for shutdown which takes care of that
and only keep the direct set mode call in the broadcast code, where we
can not touch the next_event value.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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After the patch:
commit 0b2f630a28d53b5a2082a5275bc3334b10373508
Author: Miao Xie <miaox@cn.fujitsu.com>
Date: Fri Jul 25 01:47:21 2008 -0700
cpusets: restructure the function update_cpumask() and update_nodemask()
It might happen that 'echo 0 > /cpuset/sub/cpus' returned failure but 'cpus'
has been changed, because cpus was changed before calling heap_init() which
may return -ENOMEM.
This patch restores the orginal behavior.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Andrei Gusev wrote:
> I played witch scheduler settings. After doing something like:
> echo -n 1000000 >sched_rt_period_us
>
> command is locked. I found in kernel.log:
>
> Sep 11 00:39:34 zaratustra
> Sep 11 00:39:34 zaratustra Pid: 4495, comm: bash Tainted: G W
> (2.6.26.3 #12)
> Sep 11 00:39:34 zaratustra EIP: 0060:[<c0213fc7>] EFLAGS: 00210246 CPU: 0
> Sep 11 00:39:34 zaratustra EIP is at div64_u64+0x57/0x80
> Sep 11 00:39:34 zaratustra EAX: 0000389f EBX: 00000000 ECX: 00000000
> EDX: 00000000
> Sep 11 00:39:34 zaratustra ESI: d9800000 EDI: d9800000 EBP: 0000389f
> ESP: ea7a6edc
> Sep 11 00:39:34 zaratustra DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
> Sep 11 00:39:34 zaratustra Process bash (pid: 4495, ti=ea7a6000
> task=ea744000 task.ti=ea7a6000)
> Sep 11 00:39:34 zaratustra Stack: 00000000 000003e8 d9800000 0000389f
> c0119042 00000000 00000000 00000001
> Sep 11 00:39:34 zaratustra 00000000 00000000 ea7a6f54 00010000 00000000
> c04d2e80 00000001 000e7ef0
> Sep 11 00:39:34 zaratustra c01191a3 00000000 00000000 ea7a6fa0 00000001
> ffffffff c04d2e80 ea5b2480
> Sep 11 00:39:34 zaratustra Call Trace:
> Sep 11 00:39:34 zaratustra [<c0119042>] __rt_schedulable+0x52/0x130
> Sep 11 00:39:34 zaratustra [<c01191a3>] sched_rt_handler+0x83/0x120
> Sep 11 00:39:34 zaratustra [<c01a76a6>] proc_sys_call_handler+0xb6/0xd0
> Sep 11 00:39:34 zaratustra [<c01a76c0>] proc_sys_write+0x0/0x20
> Sep 11 00:39:34 zaratustra [<c01a76d9>] proc_sys_write+0x19/0x20
> Sep 11 00:39:34 zaratustra [<c016cc68>] vfs_write+0xa8/0x140
> Sep 11 00:39:34 zaratustra [<c016cdd1>] sys_write+0x41/0x80
> Sep 11 00:39:34 zaratustra [<c0103051>] sysenter_past_esp+0x6a/0x91
> Sep 11 00:39:34 zaratustra =======================
> Sep 11 00:39:34 zaratustra Code: c8 41 0f ad f3 d3 ee f6 c1 20 0f 45 de
> 31 f6 0f ad ef d3 ed f6 c1 20 0f 45 fd 0f 45 ee 31 c9 39 eb 89 fe 89 ea
> 77 08 89 e8 31 d2 <f7> f3 89 c1 89 f0 8b 7c 24 08 f7 f3 8b 74 24 04 89
> ca 8b 1c 24
> Sep 11 00:39:34 zaratustra EIP: [<c0213fc7>] div64_u64+0x57/0x80 SS:ESP
> 0068:ea7a6edc
> Sep 11 00:39:34 zaratustra ---[ end trace 4eaa2a86a8e2da22 ]---
fix the boundary condition.
sysctl_sched_rt_period=0 makes exception at to_ratio().
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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On my tulsa x86-64 machine, kernel 2.6.25-rc5 couldn't boot randomly.
Basically, function __enable_runtime forgets to reset rt_rq->rt_throttled
to 0. When every cpu is up, per-cpu migration_thread is created and it runs
very fast, sometimes to mark the corresponding rt_rq->rt_throttled to 1 very
quickly. After all cpus are up, with below calling chain:
sched_init_smp => arch_init_sched_domains => build_sched_domains => ...
=> cpu_attach_domain => rq_attach_root => set_rq_online => ...
=> _enable_runtime
_enable_runtime is called against every rt_rq again, so rt_rq->rt_time is
reset to 0, but rt_rq->rt_throttled might be still 1. Later on function
do_sched_rt_period_timer couldn't reset it, and all RT tasks couldn't be
scheduled to run on that cpu. here is RT task migration_thread which is
woken up when a task is migrated to another cpu.
Below patch fixes it against 2.6.27-rc5.
Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The issue of the endless reprogramming loop due to a too small
min_delta_ns was fixed with the previous updates of the clock events
code, but we had no information about the spread of this problem. I
added a WARN_ON to get automated information via kerneloops.org and to
get some direct reports, which allowed me to analyse the affected
machines.
The WARN_ON has served its purpose and would be annoying for a release
kernel. Remove it and just keep the information about the increase of
the min_delta_ns value.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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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: arch_reinit_sched_domains() must destroy domains to force rebuild
sched, cpuset: rework sched domains and CPU hotplug handling (v4)
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
clocksource, acpi_pm.c: check for monotonicity
clocksource, acpi_pm.c: use proper read function also in errata mode
ntp: fix calculation of the next jiffie to trigger RTC sync
x86: HPET: read back compare register before reading counter
x86: HPET fix moronic 32/64bit thinko
clockevents: broadcast fixup possible waiters
HPET: make minimum reprogramming delta useful
clockevents: prevent endless loop lockup
clockevents: prevent multiple init/shutdown
clockevents: enforce reprogram in oneshot setup
clockevents: prevent endless loop in periodic broadcast handler
clockevents: prevent clockevent event_handler ending up handler_noop
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What I realized recently is that calling rebuild_sched_domains() in
arch_reinit_sched_domains() by itself is not enough when cpusets are enabled.
partition_sched_domains() code is trying to avoid unnecessary domain rebuilds
and will not actually rebuild anything if new domain masks match the old ones.
What this means is that doing
echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
on a system with cpusets enabled will not take affect untill something changes
in the cpuset setup (ie new sets created or deleted).
This patch fixes restore correct behaviour where domains must be rebuilt in
order to enable MC powersaving flags.
Test on quad-core Core2 box with both CONFIG_CPUSETS and !CONFIG_CPUSETS.
Also tested on dual-core Core2 laptop. Lockdep is happy and things are working
as expected.
Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
Tested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We have a bug in the calculation of the next jiffie to trigger the RTC
synchronisation. The aim here is to run sync_cmos_clock() as close as
possible to the middle of a second. Which means we want this function to
be called less than or equal to half a jiffie away from when now.tv_nsec
equals 5e8 (500000000).
If this is not the case for a given call to the function, for this purpose
instead of updating the RTC we calculate the offset in nanoseconds to the
next point in time where now.tv_nsec will be equal 5e8. The calculated
offset is then converted to jiffies as these are the unit used by the
timer.
Hovewer timespec_to_jiffies() used here uses a ceil()-type rounding mode,
where the resulting value is rounded up. As a result the range of
now.tv_nsec when the timer will trigger is from 5e8 to 5e8 + TICK_NSEC
rather than the desired 5e8 - TICK_NSEC / 2 to 5e8 + TICK_NSEC / 2.
As a result if for example sync_cmos_clock() happens to be called at the
time when now.tv_nsec is between 5e8 + TICK_NSEC / 2 and 5e8 to 5e8 +
TICK_NSEC, it will simply be rescheduled HZ jiffies later, falling in the
same range of now.tv_nsec again. Similarly for cases offsetted by an
integer multiple of TICK_NSEC.
This change addresses the problem by subtracting TICK_NSEC / 2 from the
nanosecond offset to the next point in time where now.tv_nsec will be
equal 5e8, effectively shifting the following rounding in
timespec_to_jiffies() so that it produces a rounded-to-nearest result.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Until the C1E patches arrived there where no users of periodic broadcast
before switching to oneshot mode. Now we need to trigger a possible
waiter for a periodic broadcast when switching to oneshot mode.
Otherwise we can starve them for ever.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Spencer reported a problem where utime and stime were going negative despite
the fixes in commit b27f03d4bdc145a09fb7b0c0e004b29f1ee555fa. The suspected
reason for the problem is that signal_struct maintains it's own utime and
stime (of exited tasks), these are not updated using the new task_utime()
routine, hence sig->utime can go backwards and cause the same problem
to occur (sig->utime, adds tsk->utime and not task_utime()). This patch
fixes the problem
TODO: using max(task->prev_utime, derived utime) works for now, but a more
generic solution is to implement cputime_max() and use the cputime_gt()
function for comparison.
Reported-by: spencer@bluehost.com
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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If HLT stops the TSC, we'll fail to account idle time, thereby inflating the
actual process times. Fix this by re-calibrating the clock against GTOD when
leaving nohz mode.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The C1E/HPET bug reports on AMDX2/RS690 systems where tracked down to a
too small value of the HPET minumum delta for programming an event.
The clockevents code needs to enforce an interrupt event on the clock event
device in some cases. The enforcement code was stupid and naive, as it just
added the minimum delta to the current time and tried to reprogram the device.
When the minimum delta is too small, then this loops forever.
Add a sanity check. Allow reprogramming to fail 3 times, then print a warning
and double the minimum delta value to make sure, that this does not happen again.
Use the same function for both tick-oneshot and tick-broadcast code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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While chasing the C1E/HPET bugreports I went through the clock events
code inch by inch and found that the broadcast device can be initialized
and shutdown multiple times. Multiple shutdowns are not critical, but
useless waste of time. Multiple initializations are simply broken. Another
CPU might have the device in use already after the first initialization and
the second init could just render it unusable again.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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In tick_oneshot_setup we program the device to the given next_event,
but we do not check the return value. We need to make sure that the
device is programmed enforced so the interrupt handler engine starts
working. Split out the reprogramming function from tick_program_event()
and call it with the device, which was handed in to tick_setup_oneshot().
Set the force argument, so the devices is firing an interrupt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The reprogramming of the periodic broadcast handler was broken,
when the first programming returned -ETIME. The clockevents code
stores the new expiry value in the clock events device next_event field
only when the programming time has not been elapsed yet. The loop in
question calculates the new expiry value from the next_event value
and therefor never increases.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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There is a ordering related problem with clockevents code, due to which
clockevents_register_device() called after tickless/highres switch
will not work. The new clockevent ends up with clockevents_handle_noop as
event handler, resulting in no timer activity.
The problematic path seems to be
* old device already has hrtimer_interrupt as the event_handler
* new clockevent device registers with a higher rating
* tick_check_new_device() is called
* clockevents_exchange_device() gets called
* old->event_handler is set to clockevents_handle_noop
* tick_setup_device() is called for the new device
* which sets new->event_handler using the old->event_handler which is noop.
Change the ordering so that new device inherits the proper handler.
This does not have any issue in normal case as most likely all the clockevent
devices are setup before the highres switch. But, can potentially be affecting
some corner case where HPET force detect happens after the highres switch.
This was a problem with HPET in MSI mode code that we have been experimenting
with.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We should've set refcount on the root sysctl table; otherwise we'll blow
up the first time we get down to zero dynamically registered sysctl
tables.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Make PM_QOS and CPU_IDLE play nicer when run with the RT-Preempt kernel.
The purpose of the patch is to remove the spin_lock around the read in the
function pm_qos_requirement - since spinlocks can sleep in -rt and this
function is called from idle.
CPU_IDLE polls the target_value's of some of the pm_qos parameters from
the idle loop causing sleeping locking warnings. Changing the
target_value to an atomic avoids this issue.
Remove the spinlock in pm_qos_requirement by making target_value an atomic
type.
Signed-off-by: mark gross <mgross@linux.intel.com>
Signed-off-by: John Kacur <jkacur@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We don't change pid_ns->child_reaper when the main thread of the
subnamespace init exits. As Robert Rex <robert.rex@exasol.com> pointed
out this is wrong.
Yes, the re-parenting itself works correctly, but if the reparented task
exits it needs ->parent->nsproxy->pid_ns in do_notify_parent(), and if the
main thread is zombie its ->nsproxy was already cleared by
exit_task_namespaces().
Introduce the new function, find_new_reaper(), which finds the new
->parent for the re-parenting and changes ->child_reaper if needed. Kill
the now unneeded exit_child_reaper().
Also move the changing of ->child_reaper from zap_pid_ns_processes() to
find_new_reaper(), this consolidates the games with ->child_reaper and
makes it stable under tasklist_lock.
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=11391
Reported-by: Robert Rex <robert.rex@exasol.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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zap_pid_ns_processes() sets pid_ns->child_reaper = NULL, this is wrong.
Yes, we have already killed all tasks in this namespace, and sys_wait4()
doesn't see any child. But this doesn't mean ->children list is empty, we
may have EXIT_DEAD tasks which are not visible to do_wait(). In that case
the subsequent forget_original_parent() will crash the kernel because it
will try to re-parent these tasks to the NULL reaper.
Even if there are no childs, it is not good that forget_original_parent()
uses reaper == NULL.
Change the code to set ->child_reaper = init_pid_ns.child_reaper instead.
We could use pid_ns->parent->child_reaper as well, I think this does not
really matter. These EXIT_DEAD tasks are not visible to the new ->parent
after re-parenting, they will silently do release_task() eventually.
Note that we must change ->child_reaper, otherwise
forget_original_parent() will use reaper == father, and in that case we
will hit the (correct) BUG_ON(!list_empty(&father->children)).
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current
* 'audit.b57' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current:
[PATCH] audit: Moved variable declaration to beginning of function
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The recent commit 16d9679f33caf7e683471647d1472bfe133d858 changed
check_hung_task() to filter out the TASK_KILLABLE tasks. We can
move this check to the caller which has to test t->state anyway.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix kernel-doc warning for new function:
Warning(linux-2.6.27-rc5-git2//kernel/resource.c:448): No description found for parameter 'root'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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got rid of compilation warning:
ISO C90 forbids mixed declarations and code
Signed-off-by: Cordelia Sam <cordesam@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Not used anywhere yet, but this complements the existing plain
'insert_resource()' functionality with a version that can expand the
resource we are adding in order to fix up any conflicts it has with
existing resources.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pulling the ethernet cable on a 2.6.27-rc system with NFS mounts
currently leads to an ongoing flood of soft lockup detector backtraces
for all tasks blocked on the NFS mounts when the hickup takes
longer than 120s.
I don't think NFS problems should be all that noisy.
Luckily there's a reasonably easy way to distingush this case.
Don't report task softlockup warnings for tasks in TASK_KILLABLE
state, which is used by the network file systems.
I believe this patch is a 2.6.27 candidate.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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:
exit signals: use of uninitialized field notify_count
lockdep: fix invalid list_del_rcu in zap_class
lockstat: repair erronous contention statistics
lockstat: fix numerical output rounding error
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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: rt-bandwidth accounting fix
sched: fix sched_rt_rq_enqueue() resched idle
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: update defconfigs
x86: msr: fix bogus return values from rdmsr_safe/wrmsr_safe
x86: cpuid: correct return value on partial operations
x86: msr: correct return value on partial operations
x86: cpuid: propagate error from smp_call_function_single()
x86: msr: propagate errors from smp_call_function_single()
smp: have smp_call_function_single() detect invalid CPUs
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In accordance with commit f42ac38c59e0a03d6da0c24a63fb211393f484b0
("ftrace: disable tracing for suspend to ram"), disable tracing
around the suspend code in hibernation code paths.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It fixes an accounting bug where we would continue accumulating runtime
even though the bandwidth control is disabled. This would lead to very long
throttle periods once bandwidth control gets turned on again.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When sysctl_sched_rt_runtime is set to something other than -1 and the
CONFIG_RT_GROUP_SCHED kernel parameter is NOT enabled, we get into a state
where we see one or more CPUs idling forvever even though there are
real-time
tasks in their rt runqueue that are able to run (no longer throttled).
The sequence is:
- A real-time task is running when the timer sets the rt runqueue
to throttled, and the rt task is resched_task()ed and switched
out, and idle is switched in since there are no non-rt tasks to
run on that cpu.
- Eventually the do_sched_rt_period_timer() runs and un-throttles
the rt runqueue, but we just exit the timer interrupt and go back
to executing the idle task in the idle loop forever.
If we change the sched_rt_rq_enqueue() routine to use some of the code
from the CONFIG_RT_GROUP_SCHED enabled version of this same routine and
resched_task() the currently executing task (idle in our case) if it is
a lower priority task than the higher rt task in the now un-throttled
runqueue, the problem is no longer observed.
Signed-off-by: John Blackwood <john.blackwood@ccur.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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I've been painstakingly debugging the issue with suspend to ram and
ftraced. The 2.6.28 code does not have this issue, but since the mcount
recording is not going to be in 27, this must be solved for the ftrace
daemon version.
The resume from suspend to ram would reboot because it was triple
faulting. Debugging further, I found that calling the mcount function
itself was not an issue, but it would fault when it incremented
preempt_count. preempt_count is on the tasks info structure that is on the
low memory address of the task's stack. For some reason, it could not
write to it. Resuming out of suspend to ram does quite a lot of funny
tricks to get to work, so it is not surprising at all that simply doing a
preempt_disable() would cause a fault.
Thanks to Rafael for suggesting to add a "while (1);" to find the place in
resuming that is causing the fault. I would place the loop somewhere in
the code, compile and reboot and see if it would either reboot (hit the
fault) or simply hang (hit the loop). Doing this over and over again, I
narrowed it down that it was happening in enable_nonboot_cpus.
At this point, I found that it is easier to simply disable tracing around
the suspend code, instead of searching for the particular function that
can not handle doing a preempt_disable.
This patch disables the tracer as it suspends and reenables it on resume.
I tested this patch on my Laptop, and it can resume fine with the patch.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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task->signal->notify_count is only initialized if
task->signal->group_exit_task is not NULL. Reorder a conditional so
that uninitialised memory is not used. Found by Valgrind.
Signed-off-by: Steve VanDeBogart <vandebo-lkml@nerdbox.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The problem is found during iwlagn driver testing on
v2.6.27-rc4-176-gb8e6c91 kernel, but it turns out to be a lockdep bug.
In our testing, we frequently load and unload the iwlagn driver
(>50 times). Then the MAX_STACK_TRACE_ENTRIES is reached (expected
behaviour?). The error message with the call trace is as below.
BUG: MAX_STACK_TRACE_ENTRIES too low!
turning off the locking correctness validator.
Pid: 4895, comm: iwlagn Not tainted 2.6.27-rc4 #13
Call Trace:
[<ffffffff81014aa1>] save_stack_trace+0x22/0x3e
[<ffffffff8105390a>] save_trace+0x8b/0x91
[<ffffffff81054e60>] mark_lock+0x1b0/0x8fa
[<ffffffff81056f71>] __lock_acquire+0x5b9/0x716
[<ffffffffa00d818a>] ieee80211_sta_work+0x0/0x6ea [mac80211]
[<ffffffff81057120>] lock_acquire+0x52/0x6b
[<ffffffff81045f0e>] run_workqueue+0x97/0x1ed
[<ffffffff81045f5e>] run_workqueue+0xe7/0x1ed
[<ffffffff81045f0e>] run_workqueue+0x97/0x1ed
[<ffffffff81046ae4>] worker_thread+0xd8/0xe3
[<ffffffff81049503>] autoremove_wake_function+0x0/0x2e
[<ffffffff81046a0c>] worker_thread+0x0/0xe3
[<ffffffff810493ec>] kthread+0x47/0x73
[<ffffffff8128e3ab>] trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff8100cea9>] child_rip+0xa/0x11
[<ffffffff8100c4df>] restore_args+0x0/0x30
[<ffffffff810316e1>] finish_task_switch+0x0/0xcc
[<ffffffff810493a5>] kthread+0x0/0x73
[<ffffffff8100ce9f>] child_rip+0x0/0x11
Although the above is harmless, when the ilwagn module is removed
later lockdep will trigger a kernel oops as below.
BUG: unable to handle kernel NULL pointer dereference at
0000000000000008
IP: [<ffffffff810531e1>] zap_class+0x24/0x82
PGD 73128067 PUD 7448c067 PMD 0
Oops: 0002 [1] SMP
CPU 0
Modules linked in: rfcomm l2cap bluetooth autofs4 sunrpc
nf_conntrack_ipv6 xt_state nf_conntrack xt_tcpudp ip6t_ipv6header
ip6t_REJECT ip6table_filter ip6_tables x_tables ipv6 cpufreq_ondemand
acpi_cpufreq dm_mirror dm_log dm_multipath dm_mod snd_hda_intel sr_mod
snd_seq_dummy snd_seq_oss snd_seq_midi_event battery snd_seq
snd_seq_device cdrom button snd_pcm_oss snd_mixer_oss snd_pcm
snd_timer snd_page_alloc e1000e snd_hwdep sg iTCO_wdt
iTCO_vendor_support ac pcspkr i2c_i801 i2c_core snd soundcore video
output ata_piix ata_generic libata sd_mod scsi_mod ext3 jbd mbcache
uhci_hcd ohci_hcd ehci_hcd [last unloaded: mac80211]
Pid: 4941, comm: modprobe Not tainted 2.6.27-rc4 #10
RIP: 0010:[<ffffffff810531e1>] [<ffffffff810531e1>]
zap_class+0x24/0x82
RSP: 0000:ffff88007bcb3eb0 EFLAGS: 00010046
RAX: 0000000000068ee8 RBX: ffffffff8192a0a0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000001dfb RDI: ffffffff816e70b0
RBP: ffffffffa00cd000 R08: ffffffff816818f8 R09: ffff88007c923558
R10: ffffe20002ad2408 R11: ffffffff811028ec R12: ffffffff8192a0a0
R13: 000000000002bd90 R14: 0000000000000000 R15: 0000000000000296
FS: 00007f9d1cee56f0(0000) GS:ffffffff814a58c0(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000008 CR3: 0000000073047000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process modprobe (pid: 4941, threadinfo ffff88007bcb2000, task
ffff8800758d1fc0)
Stack: ffffffff81057376 0000000000000000 ffffffffa00f7b00
0000000000000000
0000000000000080 0000000000618278 00007fff24f16720 0000000000000000
ffffffff8105d37a ffffffffa00f7b00 ffffffff8105d591 313132303863616d
Call Trace:
[<ffffffff81057376>] ? lockdep_free_key_range+0x61/0xf5
[<ffffffff8105d37a>] ? free_module+0xd4/0xe4
[<ffffffff8105d591>] ? sys_delete_module+0x1de/0x1f9
[<ffffffff8106dbfa>] ? audit_syscall_entry+0x12d/0x160
[<ffffffff8100be2b>] ? system_call_fastpath+0x16/0x1b
Code: b2 00 01 00 00 00 c3 31 f6 49 c7 c0 10 8a 61 81 eb 32 49 39 38
75 26 48 98 48 6b c0 38 48 8b 90 08 8a 61 81 48 8b 88 00 8a 61 81 <48>
89 51 08 48 89 0a 48 c7 80 08 8a 61 81 00 02 20 00 48 ff c6
RIP [<ffffffff810531e1>] zap_class+0x24/0x82
RSP <ffff88007bcb3eb0>
CR2: 0000000000000008
---[ end trace a1297e0c4abb0f2e ]---
The root cause for this oops is in add_lock_to_list() when
save_trace() fails due to MAX_STACK_TRACE_ENTRIES is reached,
entry->class is assigned but entry is never added into any lock list.
This makes the list_del_rcu() in zap_class() oops later when the
module is unloaded. This patch fixes the problem by assigning
entry->class after save_trace() returns success.
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Fix bad contention counting in /proc/lock_stat.
/proc/lockstat tries to gather per-ip contention
statistics per-lock. This was failing due to
a garbage per-ip index selector being used.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Fix rounding error in /proc/lock_stat numerical output.
On occasion the two digit fractional part contains the three
digit value '100'. This is due to a bug in the rounding algorithm
which pushes values in the range '95..99' to '100' rather than
to '00' + an increment to the integer part. For example,
- 123456.100 old display
+ 123457.00 new display
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Have smp_call_function_single() return invalid CPU indicies and return
-ENXIO. This function is already executed inside a
get_cpu()..put_cpu() which locks out CPU removal, so rather than
having the higher layers doing another layer of locking to guard
against unplugged CPUs do the test here.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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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_clock: fix cpu_clock()
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'load_module()' is a complex function that contains all the ELF section
logic, and inlining it is utterly insane. But gcc will do it, simply
because there is only one call-site. As a result, all the stack space
that is allocated for all the work to load the module will still be
active when we actually call the module init sequence, and the deep call
chain makes stack overflows happen.
And stack overflows are really hard to debug, because they not only
corrupt random pages below the stack, but also corrupt the thread_info
structure that is allocated under the stack.
In this case, Alan Brunelle reported some crazy oopses at bootup, after
loading the processor module that ends up doing complex ACPI stuff and
has quite a deep callchain. This should fix it, and is the sane thing
to do regardless.
Cc: Alan D. Brunelle <Alan.Brunelle@hp.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch fixes 3 issues:
a) it removes the dependency on jiffies, because jiffies are incremented
by a single CPU, and the tick is not synchronized between CPUs. Therefore
relying on it to calculate a window to clip whacky TSC values doesn't work
as it can drift around.
So instead use [GTOD, GTOD+TICK_NSEC) as the window.
b) __update_sched_clock() did (roughly speaking):
delta = sched_clock() - scd->tick_raw;
clock += delta;
Which gives exponential growth, instead of linear.
c) allows the sched_clock_cpu() value to warp the u64 without breaking.
the results are more reliable sched_clock() deltas:
before after sched_clock
cpu_clock: 15750 51312 51488
cpu_clock: 59719 51052 50947
cpu_clock: 15879 51249 51061
cpu_clock: 1 50933 51198
cpu_clock: 1 50931 51039
cpu_clock: 1 51093 50981
cpu_clock: 1 51043 51040
cpu_clock: 1 50959 50938
cpu_clock: 1 50981 51011
cpu_clock: 1 51364 51212
cpu_clock: 1 51219 51273
cpu_clock: 1 51389 51048
cpu_clock: 1 51285 51611
cpu_clock: 1 50964 51137
cpu_clock: 1 50973 50968
cpu_clock: 1 50967 50972
cpu_clock: 1 58910 58485
cpu_clock: 1 51082 51025
cpu_clock: 1 50957 50958
cpu_clock: 1 50958 50957
cpu_clock: 1006128 51128 50971
cpu_clock: 1 51107 51155
cpu_clock: 1 51371 51081
cpu_clock: 1 51104 51365
cpu_clock: 1 51363 51309
cpu_clock: 1 51107 51160
cpu_clock: 1 51139 51100
cpu_clock: 1 51216 51136
cpu_clock: 1 51207 51215
cpu_clock: 1 51087 51263
cpu_clock: 1 51249 51177
cpu_clock: 1 51519 51412
cpu_clock: 1 51416 51255
cpu_clock: 1 51591 51594
cpu_clock: 1 50966 51374
cpu_clock: 1 50966 50966
cpu_clock: 1 51291 50948
cpu_clock: 1 50973 50867
cpu_clock: 1 50970 50970
cpu_clock: 998306 50970 50971
cpu_clock: 1 50971 50970
cpu_clock: 1 50970 50970
cpu_clock: 1 50971 50971
cpu_clock: 1 50970 50970
cpu_clock: 1 51351 50970
cpu_clock: 1 50970 51352
cpu_clock: 1 50971 50970
cpu_clock: 1 50970 50970
cpu_clock: 1 51321 50971
cpu_clock: 1 50974 51324
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch lets the files using linux/version.h match the files that
#include it.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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: enable LB_BIAS by default
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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:
rcu: fix synchronize_rcu() so that kernel-doc works
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On the tickless system(CONFIG_NO_HZ=y and CONFIG_HIGH_RES_TIMERS=n), after
I made an offlined cpu online, I found this cpu's event handler was
tick_handle_periodic, not tick_nohz_handler.
After debuging, I found this bug was caused by the wrong tick mode. the
tick mode is not changed to NOHZ_MODE_INACTIVE when the cpu is offline.
This patch fixes this bug.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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