linux-stable.git/include/linux/nmi.h, branch v6.4.4

watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails

2023-07-19T14:35:33+00:00

[ Upstream commit 9ec272c586b07d1abf73438524bd12b1df9c5f9b ]

Patch series "watchdog: Cleanup / fixes after buddy series v5 reviews".

This patch series attempts to finish resolving the feedback received
from Petr Mladek on the v5 series I posted.

Probably the only thing that wasn't fully as clean as Petr requested was
the Kconfig stuff.  I couldn't find a better way to express it without a
more major overhaul.  In the very least, I renamed "NON_ARCH" to
"PERF_OR_BUDDY" in the hopes that will make it marginally better.

Nothing in this series is terribly critical and even the bugfixes are
small.  However, it does cleanup a few things that were pointed out in
review.

This patch (of 10):

The permissions for the kernel.nmi_watchdog sysctl have always been set at
compile time despite the fact that a watchdog can fail to probe.  Let's
fix this and set the permissions based on whether the hardlockup detector
actually probed.

Link: https://lkml.kernel.org/r/20230527014153.2793931-1-dianders@chromium.org
Link: https://lkml.kernel.org/r/20230526184139.1.I0d75971cc52a7283f495aac0bd5c3041aadc734e@changeid
Fixes: a994a3147e4c ("watchdog/hardlockup/perf: Implement init time detection of perf")
Signed-off-by: Douglas Anderson 
Reported-by: Petr Mladek 
Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley
Reviewed-by: Petr Mladek 
Cc: Christophe Leroy 
Cc: "David S. Miller" 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

watchdog/perf: adapt the watchdog_perf interface for async model

2023-07-19T14:35:33+00:00

[ Upstream commit 930d8f8dbab97cb05dba30e67a2dfa0c6dbf4bc7 ]

When lockup_detector_init()->watchdog_hardlockup_probe(), PMU may be not
ready yet.  E.g.  on arm64, PMU is not ready until
device_initcall(armv8_pmu_driver_init).  And it is deeply integrated with
the driver model and cpuhp.  Hence it is hard to push this initialization
before smp_init().

But it is easy to take an opposite approach and try to initialize the
watchdog once again later.  The delayed probe is called using workqueues.
It need to allocate memory and must be proceed in a normal context.  The
delayed probe is able to use if watchdog_hardlockup_probe() returns
non-zero which means the return code returned when PMU is not ready yet.

Provide an API - lockup_detector_retry_init() for anyone who needs to
delayed init lockup detector if they had ever failed at
lockup_detector_init().

The original assumption is: nobody should use delayed probe after
lockup_detector_check() which has __init attribute.  That is, anyone uses
this API must call between lockup_detector_init() and
lockup_detector_check(), and the caller must have __init attribute

Link: https://lkml.kernel.org/r/20230519101840.v5.16.If4ad5dd5d09fb1309cebf8bcead4b6a5a7758ca7@changeid
Reviewed-by: Petr Mladek 
Co-developed-by: Pingfan Liu 
Signed-off-by: Pingfan Liu 
Signed-off-by: Lecopzer Chen 
Signed-off-by: Douglas Anderson 
Suggested-by: Petr Mladek 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Colin Cross 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Stable-dep-of: 9ec272c586b0 ("watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails")
Signed-off-by: Sasha Levin

watchdog/hardlockup: rename some "NMI watchdog" constants/function

2023-07-19T14:35:32+00:00

[ Upstream commit df95d3085caa5b99a60eb033d7ad6c2ff2b43dbf ]

Do a search and replace of:
- NMI_WATCHDOG_ENABLED => WATCHDOG_HARDLOCKUP_ENABLED
- SOFT_WATCHDOG_ENABLED => WATCHDOG_SOFTOCKUP_ENABLED
- watchdog_nmi_ => watchdog_hardlockup_
- nmi_watchdog_available => watchdog_hardlockup_available
- nmi_watchdog_user_enabled => watchdog_hardlockup_user_enabled
- soft_watchdog_user_enabled => watchdog_softlockup_user_enabled
- NMI_WATCHDOG_DEFAULT => WATCHDOG_HARDLOCKUP_DEFAULT

Then update a few comments near where names were changed.

This is specifically to make it less confusing when we want to introduce
the buddy hardlockup detector, which isn't using NMIs.  As part of this,
we sanitized a few names for consistency.

[trix@redhat.com: make variables static]
  Link: https://lkml.kernel.org/r/20230525162822.1.I0fb41d138d158c9230573eaa37dc56afa2fb14ee@changeid
Link: https://lkml.kernel.org/r/20230519101840.v5.12.I91f7277bab4bf8c0cb238732ed92e7ce7bbd71a6@changeid
Signed-off-by: Douglas Anderson 
Signed-off-by: Tom Rix 
Reviewed-by: Tom Rix 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Colin Cross 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Lecopzer Chen 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Petr Mladek 
Cc: Pingfan Liu 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Stable-dep-of: 9ec272c586b0 ("watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails")
Signed-off-by: Sasha Levin

watchdog/hardlockup: move perf hardlockup checking/panic to common watchdog.c

2023-07-19T14:35:32+00:00

[ Upstream commit 81972551df9d168a8183b786ff4de06008469c2e ]

The perf hardlockup detector works by looking at interrupt counts and
seeing if they change from run to run.  The interrupt counts are managed
by the common watchdog code via its watchdog_timer_fn().

Currently the API between the perf detector and the common code is a
function: is_hardlockup().  When the hard lockup detector sees that
function return true then it handles printing out debug info and inducing
a panic if necessary.

Let's change the API a little bit in preparation for the buddy hardlockup
detector.  The buddy hardlockup detector wants to print nearly the same
debug info and have nearly the same panic behavior.  That means we want to
move all that code to the common file.  For now, the code in the common
file will only be there if the perf hardlockup detector is enabled, but
eventually it will be selected by a common config.

Right now, this _just_ moves the code from the perf detector file to the
common file and changes the names.  It doesn't make the changes that the
buddy hardlockup detector will need and doesn't do any style cleanups.  A
future patch will do cleanup to make it more obvious what changed.

With the above, we no longer have any callers of is_hardlockup() outside
of the "watchdog.c" file, so we can remove it from the header, make it
static, and move it to the same "#ifdef" block as our new
watchdog_hardlockup_check().  While doing this, it can be noted that even
if no hardlockup detectors were configured the existing code used to still
have the code for counting/checking "hrtimer_interrupts" even if the perf
hardlockup detector wasn't configured.  We didn't need to do that, so move
all the "hrtimer_interrupts" counting to only be there if the perf
hardlockup detector is configured as well.

This change is expected to be a no-op.

Link: https://lkml.kernel.org/r/20230519101840.v5.8.Id4133d3183e798122dc3b6205e7852601f289071@changeid
Signed-off-by: Douglas Anderson 
Reviewed-by: Petr Mladek 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Colin Cross 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Lecopzer Chen 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Pingfan Liu 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Stable-dep-of: 9ec272c586b0 ("watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails")
Signed-off-by: Sasha Levin

watchdog/hardlockup: change watchdog_nmi_enable() to void

2023-07-19T14:35:32+00:00

[ Upstream commit 730211182ed083898fa5feb4b28459ffac4c9615 ]

Nobody cares about the return value of watchdog_nmi_enable(), changing its
prototype to void.

Link: https://lkml.kernel.org/r/20230519101840.v5.4.Ic3a19b592eb1ac4c6f6eade44ffd943e8637b6e5@changeid
Signed-off-by: Pingfan Liu 
Signed-off-by: Lecopzer Chen 
Signed-off-by: Douglas Anderson 
Reviewed-by: Petr Mladek 
Acked-by: Nicholas Piggin 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Colin Cross 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Stable-dep-of: 9ec272c586b0 ("watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails")
Signed-off-by: Sasha Levin

watchdog/perf: define dummy watchdog_update_hrtimer_threshold() on correct config

2023-07-19T14:35:28+00:00

[ Upstream commit 5e008df11c55228a86a1bae692cc2002503572c9 ]

Patch series "watchdog/hardlockup: Add the buddy hardlockup detector", v5.

This patch series adds the "buddy" hardlockup detector.  In brief, the
buddy hardlockup detector can detect hardlockups without arch-level
support by having CPUs checkup on a "buddy" CPU periodically.

Given the new design of this patch series, testing all combinations is
fairly difficult. I've attempted to make sure that all combinations of
CONFIG_ options are good, but it wouldn't surprise me if I missed
something. I apologize in advance and I'll do my best to fix any
problems that are found.

This patch (of 18):

The real watchdog_update_hrtimer_threshold() is defined in
kernel/watchdog_hld.c.  That file is included if
CONFIG_HARDLOCKUP_DETECTOR_PERF and the function is defined in that file
if CONFIG_HARDLOCKUP_CHECK_TIMESTAMP.

The dummy version of the function in "nmi.h" didn't get that quite right.
While this doesn't appear to be a huge deal, it's nice to make it
consistent.

It doesn't break builds because CHECK_TIMESTAMP is only defined by x86 so
others don't get a double definition, and x86 uses perf lockup detector,
so it gets the out of line version.

Link: https://lkml.kernel.org/r/20230519101840.v5.18.Ia44852044cdcb074f387e80df6b45e892965d4a1@changeid
Link: https://lkml.kernel.org/r/20230519101840.v5.1.I8cbb2f4fa740528fcfade4f5439b6cdcdd059251@changeid
Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes")
Signed-off-by: Douglas Anderson 
Reviewed-by: Nicholas Piggin 
Reviewed-by: Petr Mladek 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Lecopzer Chen 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Pingfan Liu 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Cc: Colin Cross 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

x86/nmi: Print reasons why backtrace NMIs are ignored

2023-01-19T23:55:12+00:00

Instrument nmi_trigger_cpumask_backtrace() to dump out diagnostics based
on evidence accumulated by exc_nmi().  These diagnostics are dumped for
CPUs that ignored an NMI backtrace request for more than 10 seconds.

[ paulmck: Apply Ingo Molnar feedback. ]

Signed-off-by: Paul E. McKenney 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: "H. Peter Anvin" 
Cc: 
Reviewed-by: Ingo Molnar

watchdog: export lockup_detector_reconfigure

2022-07-27T11:35:32+00:00

In some circumstances it may be interesting to reconfigure the watchdog
from inside the kernel.

On PowerPC, this may helpful before and after a LPAR migration (LPM) is
initiated, because it implies some latencies, watchdog, and especially NMI
watchdog is expected to be triggered during this operation. Reconfiguring
the watchdog with a factor, would prevent it to happen too frequently
during LPM.

Rename lockup_detector_reconfigure() as __lockup_detector_reconfigure() and
create a new function lockup_detector_reconfigure() calling
__lockup_detector_reconfigure() under the protection of watchdog_mutex.

Signed-off-by: Laurent Dufour 
[mpe: Squash in build fix from Laurent, reported by Sachin]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220713154729.80789-3-ldufour@linux.ibm.com

sysctl: pass kernel pointers to ->proc_handler

2020-04-27T06:07:40+00:00

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig 
Acked-by: Andrey Ignatov 
Signed-off-by: Al Viro

watchdog/core: Add missing prototypes for weak functions

2018-11-06T20:58:00+00:00

The split out of the hard lockup detector exposed two new weak functions,
but no prototypes for them, which triggers the build warning:

  kernel/watchdog.c:109:12: warning: no previous prototype for ‘watchdog_nmi_enable’ [-Wmissing-prototypes]
  kernel/watchdog.c:115:13: warning: no previous prototype for ‘watchdog_nmi_disable’ [-Wmissing-prototypes]

Add the prototypes.

Fixes: 73ce0511c436 ("kernel/watchdog.c: move hardlockup detector to separate file")
Signed-off-by: Mathieu Malaterre 
Signed-off-by: Thomas Gleixner 
Cc: Babu Moger 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180606194232.17653-1-malat@debian.org