linux-toradex.git/kernel/softlockup.c, branch v2.6.23.14

softlockup: use cpu_clock() instead of sched_clock()

2007-11-26T17:42:32+00:00

patch a3b13c23f186ecb57204580cc1f2dbe9c284953a in mainline.

sched_clock() is not a reliable time-source, use cpu_clock() instead.

Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

softlockup watchdog fixes and cleanups

2007-11-26T17:42:32+00:00

This is a merge of commits a5f2ce3c6024a5bb895647b6bd88ecae5001020a and
43581a10075492445f65234384210492ff333eba in mainline to fix a warning in
the 2.6.23.3 kernel release.

softlockup watchdog: style cleanups

kernel/softirq.c grew a few style uncleanlinesses in the past few
months, clean that up. No functional changes:

text    data     bss     dec     hex filename
1126      76       4    1206     4b6 softlockup.o.before
1129      76       4    1209     4b9 softlockup.o.after

( the 3 bytes .text increase is due to the "<1>" appended to one of
the printk messages. )

Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 


softlockup: improve debug output

Improve the debuggability of kernel lockups by enhancing the debug
output of the softlockup detector: print the task that causes the lockup
and try to print a more intelligent backtrace.

The old format was:

BUG: soft lockup detected on CPU#1!
[] show_trace_log_lvl+0x19/0x2e
[] show_trace+0x12/0x14
[] dump_stack+0x14/0x16
[] softlockup_tick+0xbe/0xd0
[] run_local_timers+0x12/0x14
[] update_process_times+0x3e/0x63
[] tick_sched_timer+0x7c/0xc0
[] hrtimer_interrupt+0x135/0x1ba
[] smp_apic_timer_interrupt+0x6e/0x80
[] apic_timer_interrupt+0x33/0x38
[] syscall_call+0x7/0xb
=======================

The new format is:

BUG: soft lockup detected on CPU#1! [prctl:2363]

Pid: 2363, comm:                prctl
EIP: 0060:[] CPU: 1
EIP is at sys_prctl+0x24/0x18c
EFLAGS: 00000213    Not tainted  (2.6.22-cfs-v20 #26)
EAX: 00000001 EBX: 000003e7 ECX: 00000001 EDX: f6df0000
ESI: 000003e7 EDI: 000003e7 EBP: f6df0fb0 DS: 007b ES: 007b FS: 00d8
CR0: 8005003b CR2: 4d8c3340 CR3: 3731d000 CR4: 000006d0
[] show_trace_log_lvl+0x19/0x2e
[] show_trace+0x12/0x14
[] show_regs+0x1ab/0x1b3
[] softlockup_tick+0xef/0x108
[] run_local_timers+0x12/0x14
[] update_process_times+0x3e/0x63
[] tick_sched_timer+0x7c/0xc0
[] hrtimer_interrupt+0x135/0x1ba
[] smp_apic_timer_interrupt+0x6e/0x80
[] apic_timer_interrupt+0x33/0x38
[] syscall_call+0x7/0xb
=======================

Note that in the old format we only knew that some system call locked
up, we didnt know _which_. With the new format we know that it's at a
specific place in sys_prctl(). [which was where i created an artificial
kernel lockup to test the new format.]

This is also useful if the lockup happens in user-space - the user-space
EIP (and other registers) will be printed too. (such a lockup would
either suggest that the task was running at SCHED_FIFO:99 and looping
for more than 10 seconds, or that the softlockup detector has a
false-positive.)

The task name is printed too first, just in case we dont manage to print
a useful backtrace.

[satyam@infradead.org: fix warning]
Signed-off-by: Ingo Molnar 
Signed-off-by: Satyam Sharma 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fix the softlockup watchdog to actually work

2007-11-16T16:12:43+00:00

patch a115d5caca1a2905ba7a32b408a6042b20179aaa in mainline.

this Xen related commit:

   commit 966812dc98e6a7fcdf759cbfa0efab77500a8868
   Author: Jeremy Fitzhardinge 
   Date:   Tue May 8 00:28:02 2007 -0700

       Ignore stolen time in the softlockup watchdog

broke the softlockup watchdog to never report any lockups. (!)

print_timestamp defaults to 0, this makes the following condition
always true:

	if (print_timestamp < (touch_timestamp + 1) ||

and we'll in essence never report soft lockups.

apparently the functionality of the soft lockup watchdog was never
actually tested with that patch applied ...

Signed-off-by: Ingo Molnar 
Cc: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Freezer: make kernel threads nonfreezable by default

2007-07-17T17:23:02+00:00

Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki 
Acked-by: Nigel Cunningham 
Cc: Pavel Machek 
Cc: Oleg Nesterov 
Cc: Gautham R Shenoy 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Add suspend-related notifications for CPU hotplug

2007-05-09T19:30:56+00:00

Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki 
Cc: Gautham R Shenoy 
Cc: Pavel Machek 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

add touch_all_softlockup_watchdogs()

2007-05-08T18:15:06+00:00

Add touch_all_softlockup_watchdogs() to allow the softlockup watchdog
timers on all cpus to be updated.  This is used to prevent sysrq-t from
generating a spurious watchdog message when generating lots of output.

Softlockup watchdogs use sched_clock() as its timebase, which is inherently
per-cpu (at least, when it is measuring unstolen time).  Because of this,
it isn't possible for one CPU to directly update the other CPU's timers,
but it is possible to tell the other CPUs to do update themselves
appropriately.

Signed-off-by: Jeremy Fitzhardinge 
Acked-by: Chris Lalancette 
Signed-off-by: Prarit Bhargava 
Cc: Rick Lindsley 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Ignore stolen time in the softlockup watchdog

2007-05-08T18:15:06+00:00

The softlockup watchdog is currently a nuisance in a virtual machine, since
the whole system could have the CPU stolen from it for a long period of
time.  While it would be unlikely for a guest domain to be denied timer
interrupts for over 10s, it could happen and any softlockup message would
be completely spurious.

Earlier I proposed that sched_clock() return time in unstolen nanoseconds,
which is how Xen and VMI currently implement it.  If the softlockup
watchdog uses sched_clock() to measure time, it would automatically ignore
stolen time, and therefore only report when the guest itself locked up.
When running native, sched_clock() returns real-time nanoseconds, so the
behaviour would be unchanged.

Note that sched_clock() used this way is inherently per-cpu, so this patch
makes sure that the per-processor watchdog thread initialized its own
timestamp.

Signed-off-by: Jeremy Fitzhardinge 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: john stultz 
Cc: Zachary Amsden 
Cc: James Morris 
Cc: Dan Hecht 
Cc: Paul Mackerras 
Cc: Martin Schwidefsky 
Cc: Prarit Bhargava 
Cc: Chris Lalancette 
Cc: Rick Lindsley 
Cc: Eric Dumazet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

softlockup: s/99/MAX_RT_PRIO/

2007-05-08T18:14:59+00:00

Don't use hardcoded 99 value, use MAX_RT_PRIO.

Signed-off-by: Oleg Nesterov 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] check return value of cpu_callback

2006-09-29T16:18:14+00:00

Spawing ksoftirqd, migration, or watchdog, and calling init_timers_cpu()
may fail with small memory.  If it happens in initcalls, kernel NULL
pointer dereference happens later.  This patch makes crash happen
immediately in such cases.  It seems a bit better than getting kernel NULL
pointer dereference later.

Cc: Ingo Molnar 
Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] cpu hotplug: replace devinit* with cpuinit* for cpu notifications

2006-07-31T20:28:39+00:00

Few of the callback functions and notifier blocks that are associated with cpu
notifications incorrectly have __devinit and __devinitdata.  They should be
__cpuinit and __cpuinitdata instead.

It makes no functional difference but wastes text area when CONFIG_HOTPLUG is
enabled and CONFIG_HOTPLUG_CPU is not.

This patch fixes all those instances.

Signed-off-by: Chandra Seetharaman 
Cc: Ashok Raj 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds