05 Sep, 2018
1 commit
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commit cb9d7fd51d9fbb329d182423bd7b92d0f8cb0e01 upstream.
Some architectures need to use stop_machine() to patch functions for
ftrace, and the assumption is that the stopped CPUs do not make function
calls to traceable functions when they are in the stopped state.Commit ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after
MULTI_STOP_PREPARE") added calls to the watchdog touch functions from
the stopped CPUs and those functions lack notrace annotations. This
leads to crashes when enabling/disabling ftrace on ARM kernels built
with the Thumb-2 instruction set.Fix it by adding the necessary notrace annotations.
Fixes: ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: Vincent Whitchurch
Signed-off-by: Thomas Gleixner
Cc: Peter Zijlstra
Cc: oleg@redhat.com
Cc: tj@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
Signed-off-by: Greg Kroah-Hartman
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
04 Oct, 2017
5 commits
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The variable is unused when the softlockup detector is disabled in Kconfig.
Signed-off-by: Thomas Gleixner
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The function names made sense up to the point where the watchdog
(re)configuration was unified to use softlockup_reconfigure_threads() for
all configuration purposes. But that includes scenarios which solely
configure the nmi watchdog.Rename softlockup_reconfigure_threads() and softlockup_init_threads() so
the function names match the functionality.Signed-off-by: Thomas Gleixner
Cc: Linus Torvalds
Cc: Michael Ellerman
Cc: Peter Zijlstra
Cc: Don Zickus -
The rework of the core hotplug code triggers the WARN_ON in start_wd_cpu()
on powerpc because it is called multiple times for the boot CPU.The first call is via:
start_wd_on_cpu+0x80/0x2f0
watchdog_nmi_reconfigure+0x124/0x170
softlockup_reconfigure_threads+0x110/0x130
lockup_detector_init+0xbc/0xe0
kernel_init_freeable+0x18c/0x37c
kernel_init+0x2c/0x160
ret_from_kernel_thread+0x5c/0xbcAnd then again via the CPU hotplug registration:
start_wd_on_cpu+0x80/0x2f0
cpuhp_invoke_callback+0x194/0x620
cpuhp_thread_fun+0x7c/0x1b0
smpboot_thread_fn+0x290/0x2a0
kthread+0x168/0x1b0
ret_from_kernel_thread+0x5c/0xbcThis can be avoided by setting up the cpu hotplug state with nocalls and
move the initialization to the watchdog_nmi_probe() function. That
initializes the hotplug callbacks without invoking the callback and the
following core initialization function then configures the watchdog for the
online CPUs (in this case CPU0) via softlockup_reconfigure_threads().Reported-and-tested-by: Michael Ellerman
Signed-off-by: Thomas Gleixner
Acked-by: Michael Ellerman
Cc: Benjamin Herrenschmidt
Cc: Nicholas Piggin
Cc: linuxppc-dev@lists.ozlabs.org -
Instead of dropping the cpu hotplug lock after stopping NMI watchdog and
threads and reaquiring for restart, the code and the protection rules
become more obvious when holding cpu hotplug lock across the full
reconfiguration.Suggested-by: Linus Torvalds
Signed-off-by: Thomas Gleixner
Acked-by: Michael Ellerman
Cc: Peter Zijlstra
Cc: Don Zickus
Cc: Benjamin Herrenschmidt
Cc: Nicholas Piggin
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710022105570.2114@nanos -
The recent cleanup of the watchdog code split watchdog_nmi_reconfigure()
into two stages. One to stop the NMI and one to restart it after
reconfiguration. That was done by adding a boolean 'run' argument to the
code, which is functionally correct but not necessarily a piece of art.Replace it by two explicit functions: watchdog_nmi_stop() and
watchdog_nmi_start().Fixes: 6592ad2fcc8f ("watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage")
Requested-by: Linus 'Nursing his pet-peeve' Torvalds
Signed-off-by: Thomas 'Mopping up garbage' Gleixner
Acked-by: Michael Ellerman
Cc: Peter Zijlstra
Cc: Don Zickus
Cc: Benjamin Herrenschmidt
Cc: Nicholas Piggin
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710021957480.2114@nanos
14 Sep, 2017
21 commits
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All watchdog thread related functions are delegated to the smpboot thread
infrastructure, which handles serialization against CPU hotplug correctly.The sysctl interface is completely decoupled from anything which requires
CPU hotplug protection.No need to protect the sysctl writes against cpu hotplug anymore. Remove it
and add the now required protection to the powerpc arch_nmi_watchdog
implementation.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Benjamin Herrenschmidt
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Michael Ellerman
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170912194148.418497420@linutronix.de
Signed-off-by: Ingo Molnar -
Get rid of the hodgepodge which tries to be smart about perf being
unavailable and error printout rate limiting.That's all not required simply because this is never invoked when the perf
NMI watchdog is not functional.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194148.259651788@linutronix.de
Signed-off-by: Ingo Molnar -
Use the init time detection of the perf NMI watchdog to determine whether
the perf NMI watchdog is functional. If not disable it permanentely. It
won't come back magically at runtime.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194148.099799541@linutronix.de
Signed-off-by: Ingo Molnar -
Letting user space poke directly at variables which are used at run time is
stupid and causes a lot of race conditions and other issues.Seperate the user variables and on change invoke the reconfiguration, which
then stops the watchdogs, reevaluates the new user value and restarts the
watchdogs with the new parameters.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.939985640@linutronix.de
Signed-off-by: Ingo Molnar -
Both the perf reconfiguration and the powerpc watchdog_nmi_reconfigure()
need to be done in two steps.1) Stop all NMIs
2) Read the new parameters and start NMIsRight now watchdog_nmi_reconfigure() is a combination of both. To allow a
clean reconfiguration add a 'run' argument and split the functionality in
powerpc.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Benjamin Herrenschmidt
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Michael Ellerman
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170912194147.862865570@linutronix.de
Signed-off-by: Ingo Molnar -
Reflect that these variables are user interface related and remove the
whitespace damage in the sysctl table while at it.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.783210221@linutronix.de
Signed-off-by: Ingo Molnar -
Use a single function to update sysctl changes. This is not a high
frequency user space interface and it's root only.Preparatory patch to cleanup the sysctl variable handling.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.549114957@linutronix.de
Signed-off-by: Ingo Molnar -
The lockup detector reconfiguration tears down all watchdog threads when
the watchdog is disabled and sets them up again when its enabled.That's a pointless exercise. The watchdog threads are not consuming an
insane amount of resources, so it's enough to set them up at init time and
keep them in parked position when the watchdog is disabled and unpark them
when it is reenabled. The smpboot thread infrastructure takes care of
keeping the force parked threads in place even across cpu hotplug.Aside of that the code implements the park/unpark facility of smp hotplug
threads on its own, which is even more pointless. We have functionality in
the smpboot thread code to do so.Use the new thread management functions and get rid of the unholy mess.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.470370113@linutronix.de
Signed-off-by: Ingo Molnar -
The lockup detector reconfiguration tears down all watchdog threads when
the watchdog is disabled and sets them up again when its enabled.That's a pointless exercise. The watchdog threads are not consuming an
insane amount of resources, so it's enough to set them up at init time and
keep them in parked position when the watchdog is disabled and unpark them
when it is reenabled. The smpboot thread infrastructure takes care of
keeping the force parked threads in place even across cpu hotplug.Another horrible mechanism are the open coded park/unpark loops which are
used for reconfiguration of the watchdog. The smpboot infrastructure allows
exactly the same via smpboot_update_cpumask_thread_percpu(), which is cpu
hotplug safe. Using that instead of the open coded loops allows to get rid
of the hotplug locking mess in the watchdog code.Implement a clean infrastructure which allows to replace the open coded
nonsense.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.377182587@linutronix.de
Signed-off-by: Ingo Molnar -
smpboot_update_cpumask_threads_percpu() allocates a temporary cpumask at
runtime. This is suboptimal because the call site needs more code size for
proper error handling than a statically allocated temporary mask requires
data size.Add static temporary cpumask. The function is globaly serialized, so no
further protection required.Remove the half baken error handling in the watchdog code and get rid of
the export as there are no in tree modular users of that function.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.297288838@linutronix.de
Signed-off-by: Ingo Molnar -
Split the write part of the cpumask proc handler out into a separate helper
to avoid deep indentation. This also reduces the patch complexity in the
following cleanups.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.218075991@linutronix.de
Signed-off-by: Ingo Molnar -
The #ifdef maze in this file is horrible, group stuff at least a bit so one
can figure out what belongs to what.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.139629546@linutronix.de
Signed-off-by: Ingo Molnar -
Having stub functions which take a full page is not helping the
readablility of code.Condense them and move the doubled #ifdef variant into the SYSFS section.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194147.045545271@linutronix.de
Signed-off-by: Ingo Molnar -
Commit:
b94f51183b06 ("kernel/watchdog: prevent false hardlockup on overloaded system")
tries to fix the following issue:
proc_write()
set_sample_period() park()
disable_nmi()
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1709052038270.2393@nanos
Signed-off-by: Ingo Molnar -
The following deadlock is possible in the watchdog hotplug code:
cpus_write_lock()
...
takedown_cpu()
smpboot_park_threads()
smpboot_park_thread()
kthread_park()
->park() := watchdog_disable()
watchdog_nmi_disable()
perf_event_release_kernel();
put_event()
_free_event()
->destroy() := hw_perf_event_destroy()
x86_release_hardware()
release_ds_buffers()
get_online_cpus()when a per cpu watchdog perf event is destroyed which drops the last
reference to the PMU hardware. The cleanup code there invokes
get_online_cpus() which instantly deadlocks because the hotplug percpu
rwsem is write locked.To solve this add a deferring mechanism:
cpus_write_lock()
kthread_park()
watchdog_nmi_disable(deferred)
perf_event_disable(event);
move_event_to_deferred(event);
....
cpus_write_unlock()
cleaup_deferred_events()
perf_event_release_kernel()This is still properly serialized against concurrent hotplug via the
cpu_add_remove_lock, which is held by the task which initiated the hotplug
event.This is also used to handle event destruction when the watchdog threads are
parked via other mechanisms than CPU hotplug.Analyzed-by: Peter Zijlstra
Reported-by: Borislav Petkov
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.884469246@linutronix.de
Signed-off-by: Ingo Molnar -
The self disabling feature is broken vs. CPU hotplug locking:
CPU 0 CPU 1
cpus_write_lock();
cpu_up(1)
wait_for_completion()
....
unpark_watchdog()
->unpark()
perf_event_create() parked);Result: End of hotplug and instantaneous full lockup of the machine.
There is a similar problem with disabling the watchdog via the user space
interface as the sysctl function fiddles with watchdog_enable directly.It's very debatable whether this is required at all. If the watchdog works
nicely on N CPUs and it fails to enable on the N + 1 CPU either during
hotplug or because the user space interface disabled it via sysctl cpumask
and then some perf user grabbed the counter which is then unavailable for
the watchdog when the sysctl cpumask gets changed back.There is no real justification for this.
One of the reasons WHY this is done is the utter stupidity of the init code
of the perf NMI watchdog. Instead of checking upfront at boot whether PERF
is available and functional at all, it just does this check at run time
over and over when user space fiddles with the sysctl. That's broken beyond
repair along with the idiotic error code dependent warn level printks and
the even more silly printk rate limiting.If the init code checks whether perf works at boot time, then this mess can
be more or less avoided completely. Perf does not come magically into life
at runtime. Brain usage while coding is overrated.Remove the cruft and add a temporary safe guard which gets removed later.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.806708429@linutronix.de
Signed-off-by: Ingo Molnar -
The function is only used by the KVM init code. Mark it __init to prevent
creative abuse.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.727134632@linutronix.de
Signed-off-by: Ingo Molnar -
Following patches will use the mutex for other purposes as well. Rename it
as it is not longer a proc specific thing.Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.647714850@linutronix.de
Signed-off-by: Ingo Molnar -
The watchdog proc interface causes extensive recursive locking of the CPU
hotplug percpu rwsem, which is deadlock prone.Replace the get/put_online_cpus() pairs with cpu_hotplug_disable()/enable()
calls for now. Later patches will remove that requirement completely.Reported-by: Borislav Petkov
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.568079057@linutronix.de
Signed-off-by: Ingo Molnar -
This interface has several issues:
- It's causing recursive locking of the hotplug lock.
- It's complete overkill to teardown all threads and then recreate them
The same can be achieved with the simple hardlockup_detector_perf_stop /
restart() interfaces. The abuse from the busy looping poweroff() loop of
PARISC has been solved as well.Remove the cruft.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Link: http://lkml.kernel.org/r/20170912194146.487537732@linutronix.de
Signed-off-by: Ingo Molnar -
PARISC has a a busy looping power off routine. If the watchdog is enabled
the watchdog timer will still fire, but the thread is not running, which
causes the softlockup watchdog to trigger.Provide a interface which allows to turn the watchdog off.
Signed-off-by: Thomas Gleixner
Reviewed-by: Don Zickus
Cc: Andrew Morton
Cc: Borislav Petkov
Cc: Chris Metcalf
Cc: Helge Deller
Cc: Linus Torvalds
Cc: Nicholas Piggin
Cc: Peter Zijlstra
Cc: Sebastian Siewior
Cc: Ulrich Obergfell
Cc: linux-parisc@vger.kernel.org
Link: http://lkml.kernel.org/r/20170912194146.327343752@linutronix.de
Signed-off-by: Ingo Molnar
18 Aug, 2017
1 commit
-
The hardlockup detector on x86 uses a performance counter based on unhalted
CPU cycles and a periodic hrtimer. The hrtimer period is about 2/5 of the
performance counter period, so the hrtimer should fire 2-3 times before the
performance counter NMI fires. The NMI code checks whether the hrtimer
fired since the last invocation. If not, it assumess a hard lockup.The calculation of those periods is based on the nominal CPU
frequency. Turbo modes increase the CPU clock frequency and therefore
shorten the period of the perf/NMI watchdog. With extreme Turbo-modes (3x
nominal frequency) the perf/NMI period is shorter than the hrtimer period
which leads to false positives.A simple fix would be to shorten the hrtimer period, but that comes with
the side effect of more frequent hrtimer and softlockup thread wakeups,
which is not desired.Implement a low pass filter, which checks the perf/NMI period against
kernel time. If the perf/NMI fires before 4/5 of the watchdog period has
elapsed then the event is ignored and postponed to the next perf/NMI.That solves the problem and avoids the overhead of shorter hrtimer periods
and more frequent softlockup thread wakeups.Fixes: 58687acba592 ("lockup_detector: Combine nmi_watchdog and softlockup detector")
Reported-and-tested-by: Kan Liang
Signed-off-by: Thomas Gleixner
Cc: dzickus@redhat.com
Cc: prarit@redhat.com
Cc: ak@linux.intel.com
Cc: babu.moger@oracle.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: acme@redhat.com
Cc: stable@vger.kernel.org
Cc: atomlin@redhat.com
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1708150931310.1886@nanos
15 Jul, 2017
1 commit
-
After commit 73ce0511c436 ("kernel/watchdog.c: move hardlockup
detector to separate file"), 'NMI watchdog' is inappropriate in
kernel/watchdog.c, using 'watchdog' only.Link: http://lkml.kernel.org/r/1499928642-48983-1-git-send-email-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang
Cc: Babu Moger
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Jul, 2017
2 commits
-
After reconfiguring watchdog sysctls etc., architecture specific
watchdogs may not get all their parameters updated.watchdog_nmi_reconfigure() can be implemented to pull the new values in
and set the arch NMI watchdog.[npiggin@gmail.com: add code comments]
Link: http://lkml.kernel.org/r/20170617125933.774d3858@roar.ozlabs.ibm.com
[arnd@arndb.de: hide unused function]
Link: http://lkml.kernel.org/r/20170620204854.966601-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170616065715.18390-5-npiggin@gmail.com
Signed-off-by: Nicholas Piggin
Signed-off-by: Arnd Bergmann
Reviewed-by: Don Zickus
Tested-by: Babu Moger [sparc]
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Michael Ellerman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Split SOFTLOCKUP_DETECTOR from LOCKUP_DETECTOR, and split
HARDLOCKUP_DETECTOR_PERF from HARDLOCKUP_DETECTOR.LOCKUP_DETECTOR implies the general boot, sysctl, and programming
interfaces for the lockup detectors.An architecture that wants to use a hard lockup detector must define
HAVE_HARDLOCKUP_DETECTOR_PERF or HAVE_HARDLOCKUP_DETECTOR_ARCH.Alternatively an arch can define HAVE_NMI_WATCHDOG, which provides the
minimum arch_touch_nmi_watchdog, and it otherwise does its own thing and
does not implement the LOCKUP_DETECTOR interfaces.sparc is unusual in that it has started to implement some of the
interfaces, but not fully yet. It should probably be converted to a full
HAVE_HARDLOCKUP_DETECTOR_ARCH.[npiggin@gmail.com: fix]
Link: http://lkml.kernel.org/r/20170617223522.66c0ad88@roar.ozlabs.ibm.com
Link: http://lkml.kernel.org/r/20170616065715.18390-4-npiggin@gmail.com
Signed-off-by: Nicholas Piggin
Reviewed-by: Don Zickus
Reviewed-by: Babu Moger
Tested-by: Babu Moger [sparc]
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Michael Ellerman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
02 Mar, 2017
3 commits
-
We are going to split out of , which
will have to be picked up from other headers and a couple of .c files.Create a trivial placeholder file that just
maps to to make this patch obviously correct and
bisectable.Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
We are going to move scheduler ABI details to ,
which will be used from a number of .c files.Create empty placeholder header that maps to .
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
We are going to split out of , which
will have to be picked up from other headers and .c files.Create a trivial placeholder file that just
maps to to make this patch obviously correct and
bisectable.Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
25 Jan, 2017
1 commit
-
On an overloaded system, it is possible that a change in the watchdog
threshold can be delayed long enough to trigger a false positive.This can easily be achieved by having a cpu spinning indefinitely on a
task, while another cpu updates watchdog threshold.What happens is while trying to park the watchdog threads, the hrtimers
on the other cpus trigger and reprogram themselves with the new slower
watchdog threshold. Meanwhile, the nmi watchdog is still programmed
with the old faster threshold.Because the one cpu is blocked, it prevents the thread parking on the
other cpus from completing, which is needed to shutdown the nmi watchdog
and reprogram it correctly. As a result, a false positive from the nmi
watchdog is reported.Fix this by setting a park_in_progress flag to block all lockups until
the parking is complete.Fix provided by Ulrich Obergfell.
[akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/]
Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.com
Signed-off-by: Don Zickus
Reviewed-by: Aaron Tomlin
Cc: Ulrich Obergfell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Dec, 2016
3 commits
-
Separate hardlockup code from watchdog.c and move it to watchdog_hld.c.
It is mostly straight forward. Remove everything inside
CONFIG_HARDLOCKUP_DETECTORS. This code will go to file watchdog_hld.c.
Also update the makefile accordigly.Link: http://lkml.kernel.org/r/1478034826-43888-3-git-send-email-babu.moger@oracle.com
Signed-off-by: Babu Moger
Acked-by: Don Zickus
Cc: Ingo Molnar
Cc: Jiri Kosina
Cc: Andi Kleen
Cc: Yaowei Bai
Cc: Aaron Tomlin
Cc: Ulrich Obergfell
Cc: Tejun Heo
Cc: Hidehiro Kawai
Cc: Josh Hunt
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Patch series "Clean up watchdog handlers", v2.
This is an attempt to cleanup watchdog handlers. Right now,
kernel/watchdog.c implements both softlockup and hardlockup detectors.
Softlockup code is generic. Hardlockup code is arch specific. Some
architectures don't use hardlockup detectors. They use their own
watchdog detectors. To make both these combination work, we have
numerous #ifdefs in kernel/watchdog.c.We are trying here to make these handlers independent of each other.
Also provide an interface for architectures to implement their own
handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
as weak such that architectures can override its definitions.Thanks to Don Zickus for his suggestions.
Here are our previous discussions
http://www.spinics.net/lists/sparclinux/msg16543.html
http://www.spinics.net/lists/sparclinux/msg16441.htmlThis patch (of 3):
Move shared macros and definitions to nmi.h so that watchdog.c, new file
watchdog_hld.c or any other architecture specific handler can use those
definitions.Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.com
Signed-off-by: Babu Moger
Acked-by: Don Zickus
Cc: Ingo Molnar
Cc: Jiri Kosina
Cc: Andi Kleen
Cc: Yaowei Bai
Cc: Aaron Tomlin
Cc: Ulrich Obergfell
Cc: Tejun Heo
Cc: Hidehiro Kawai
Cc: Josh Hunt
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
NMI handler doesn't call set_irq_regs(), it's set only by normal IRQ.
Thus get_irq_regs() returns NULL or stale registers snapshot with IP/SP
pointing to the code interrupted by IRQ which was interrupted by NMI.
NULL isn't a problem: in this case watchdog calls dump_stack() and
prints full stack trace including NMI. But if we're stuck in IRQ
handler then NMI watchlog will print stack trace without IRQ part at
all.This patch uses registers snapshot passed into NMI handler as arguments:
these registers point exactly to the instruction interrupted by NMI.Fixes: 55537871ef66 ("kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup")
Link: http://lkml.kernel.org/r/146771764784.86724.6006627197118544150.stgit@buzz
Signed-off-by: Konstantin Khlebnikov
Cc: Jiri Kosina
Cc: Ulrich Obergfell
Cc: Aaron Tomlin
Cc: [4.4+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Mar, 2016
1 commit
-
While working on a script to restore all sysctl params before a series of
tests I found that writing any value into the
/proc/sys/kernel/{nmi_watchdog,soft_watchdog,watchdog,watchdog_thresh}
causes them to call proc_watchdog_update().NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.There doesn't appear to be a reason for doing this work every time a write
occurs, so only do it when the values change.Signed-off-by: Josh Hunt
Acked-by: Don Zickus
Reviewed-by: Aaron Tomlin
Cc: Ulrich Obergfell
Cc: [4.1.x+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
