Commit Graph

219 Commits

Author SHA1 Message Date
Petr Mladek 47f4cb4339 watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64
The HAVE_ prefix means that the code could be enabled. Add another
variable for HAVE_HARDLOCKUP_DETECTOR_SPARC64 without this prefix.
It will be set when it should be built. It will make it compatible
with the other hardlockup detectors.

Before, it is far from obvious that the SPARC64 variant is actually used:

$> make ARCH=sparc64 defconfig
$> grep HARDLOCKUP_DETECTOR .config
CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y
CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y

After, it is more clear:

$> make ARCH=sparc64 defconfig
$> grep HARDLOCKUP_DETECTOR .config
CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y
CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y
CONFIG_HARDLOCKUP_DETECTOR_SPARC64=y

Link: https://lkml.kernel.org/r/20230616150618.6073-6-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:29 -07:00
Petr Mladek a5fcc2367e watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific
There are several hardlockup detector implementations and several Kconfig
values which allow selection and build of the preferred one.

CONFIG_HARDLOCKUP_DETECTOR was introduced by the commit 23637d477c
("lockup_detector: Introduce CONFIG_HARDLOCKUP_DETECTOR") in v2.6.36.
It was a preparation step for introducing the new generic perf hardlockup
detector.

The existing arch-specific variants did not support the to-be-created
generic build configurations, sysctl interface, etc. This distinction
was made explicit by the commit 4a7863cc2e ("x86, nmi_watchdog:
Remove ARCH_HAS_NMI_WATCHDOG and rely on CONFIG_HARDLOCKUP_DETECTOR")
in v2.6.38.

CONFIG_HAVE_NMI_WATCHDOG was introduced by the commit d314d74c69
("nmi watchdog: do not use cpp symbol in Kconfig") in v3.4-rc1. It replaced
the above mentioned ARCH_HAS_NMI_WATCHDOG. At that time, it was still used
by three architectures, namely blackfin, mn10300, and sparc.

The support for blackfin and mn10300 architectures has been completely
dropped some time ago. And sparc is the only architecture with the historic
NMI watchdog at the moment.

And the old sparc implementation is really special. It is always built on
sparc64. It used to be always enabled until the commit 7a5c8b57ce
("sparc: implement watchdog_nmi_enable and watchdog_nmi_disable") added
in v4.10-rc1.

There are only few locations where the sparc64 NMI watchdog interacts
with the generic hardlockup detectors code:

  + implements arch_touch_nmi_watchdog() which is called from the generic
    touch_nmi_watchdog()

  + implements watchdog_hardlockup_enable()/disable() to support
    /proc/sys/kernel/nmi_watchdog

  + is always preferred over other generic watchdogs, see
    CONFIG_HARDLOCKUP_DETECTOR

  + includes asm/nmi.h into linux/nmi.h because some sparc-specific
    functions are needed in sparc-specific code which includes
    only linux/nmi.h.

The situation became more complicated after the commit 05a4a95279
("kernel/watchdog: split up config options") and commit 2104180a53
("powerpc/64s: implement arch-specific hardlockup watchdog") in v4.13-rc1.
They introduced HAVE_HARDLOCKUP_DETECTOR_ARCH. It was used for powerpc
specific hardlockup detector. It was compatible with the perf one
regarding the general boot, sysctl, and programming interfaces.

HAVE_HARDLOCKUP_DETECTOR_ARCH was defined as a superset of
HAVE_NMI_WATCHDOG. It made some sense because all arch-specific
detectors had some common requirements, namely:

  + implemented arch_touch_nmi_watchdog()
  + included asm/nmi.h into linux/nmi.h
  + defined the default value for /proc/sys/kernel/nmi_watchdog

But it actually has made things pretty complicated when the generic
buddy hardlockup detector was added. Before the generic perf detector
was newer supported together with an arch-specific one. But the buddy
detector could work on any SMP system. It means that an architecture
could support both the arch-specific and buddy detector.

As a result, there are few tricky dependencies. For example,
CONFIG_HARDLOCKUP_DETECTOR depends on:

  ((HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY) && !HAVE_NMI_WATCHDOG) || HAVE_HARDLOCKUP_DETECTOR_ARCH

The problem is that the very special sparc implementation is defined as:

  HAVE_NMI_WATCHDOG && !HAVE_HARDLOCKUP_DETECTOR_ARCH

Another problem is that the meaning of HAVE_NMI_WATCHDOG is far from clear
without reading understanding the history.

Make the logic less tricky and more self-explanatory by making
HAVE_NMI_WATCHDOG specific for the sparc64 implementation. And rename it to
HAVE_HARDLOCKUP_DETECTOR_SPARC64.

Note that HARDLOCKUP_DETECTOR_PREFER_BUDDY, HARDLOCKUP_DETECTOR_PERF,
and HARDLOCKUP_DETECTOR_BUDDY may conflict only with
HAVE_HARDLOCKUP_DETECTOR_ARCH. They depend on HARDLOCKUP_DETECTOR
and it is not longer enabled when HAVE_NMI_WATCHDOG is set.

Link: https://lkml.kernel.org/r/20230616150618.6073-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:29 -07:00
Douglas Anderson 28168eca32 watchdog/hardlockup: move SMP barriers from common code to buddy code
It's been suggested that since the SMP barriers are only potentially
useful for the buddy hardlockup detector, not the perf hardlockup
detector, that the barriers belong in the buddy code.  Let's move them and
add clearer comments about why they're needed.

Link: https://lkml.kernel.org/r/20230526184139.9.I5ab0a0eeb0bd52fb23f901d298c72fa5c396e22b@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:28 -07:00
Douglas Anderson d3b62ace0f watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called
In the patch ("watchdog/hardlockup: detect hard lockups using secondary
(buddy) CPUs"), we added a call from the common watchdog.c file into the
buddy.  That call could be done more cleanly.  Specifically:

1. If we move the call into watchdog_hardlockup_kick() then it keeps
   watchdog_timer_fn() simpler.
2. We don't need to pass an "unsigned long" to the buddy for the timer
   count. In the patch ("watchdog/hardlockup: add a "cpu" param to
   watchdog_hardlockup_check()") the count was changed to "atomic_t"
   which is backed by an int, so we should match types.

Link: https://lkml.kernel.org/r/20230526184139.6.I006c7d958a1ea5c4e1e4dc44a25596d9bb5fd3ba@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:27 -07:00
Douglas Anderson 7a71d8e650 watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy()
In the patch ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") we started using a cpumask to keep track of
which CPUs to backtrace.  When setting up this cpumask, it's better to use
cpumask_copy() than to just copy the structure directly.  Fix this.

Link: https://lkml.kernel.org/r/20230526184139.4.Iccee2d1ea19114dafb6553a854ea4d8ab2a3f25b@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:27 -07:00
Douglas Anderson 2711e4adef watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick()
In the patch ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") there was no reason to use raw_cpu_ptr(). 
Using this_cpu_ptr() works fine.

Link: https://lkml.kernel.org/r/20230526184139.3.I660e103077dcc23bb29aaf2be09cb234e0495b2d@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:27 -07:00
Douglas Anderson 6426e8d1f2 watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
Right now there is one arch (sparc64) that selects HAVE_NMI_WATCHDOG
without selecting HAVE_HARDLOCKUP_DETECTOR_ARCH.  Because of that one
architecture, we have some special case code in the watchdog core to
handle the fact that watchdog_hardlockup_probe() isn't implemented.

Let's implement watchdog_hardlockup_probe() for sparc64 and get rid of the
special case.

As a side effect of doing this, code inspection tells us that we could fix
a minor bug where the system won't properly realize that NMI watchdogs are
disabled.  Specifically, on powerpc if CONFIG_PPC_WATCHDOG is turned off
the arch might still select CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH which
selects CONFIG_HAVE_NMI_WATCHDOG.  Since CONFIG_PPC_WATCHDOG was off then
nothing will override the "weak" watchdog_hardlockup_probe() and we'll
fallback to looking at CONFIG_HAVE_NMI_WATCHDOG.

Link: https://lkml.kernel.org/r/20230526184139.2.Ic6ebbf307ca0efe91f08ce2c1eb4a037ba6b0700@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:26 -07:00
Douglas Anderson 9ec272c586 watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails
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: a994a3147e ("watchdog/hardlockup/perf: Implement init time detection of perf")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reported-by: Petr Mladek <pmladek@suse.com>
Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:25:26 -07:00
Lecopzer Chen 930d8f8dba watchdog/perf: adapt the watchdog_perf interface for async model
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 <pmladek@suse.com>
Co-developed-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:21 -07:00
Douglas Anderson 1f423c905a watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs
Implement a hardlockup detector that doesn't doesn't need any extra
arch-specific support code to detect lockups.  Instead of using something
arch-specific we will use the buddy system, where each CPU watches out for
another one.  Specifically, each CPU will use its softlockup hrtimer to
check that the next CPU is processing hrtimer interrupts by verifying that
a counter is increasing.

NOTE: unlike the other hard lockup detectors, the buddy one can't easily
show what's happening on the CPU that locked up just by doing a simple
backtrace.  It relies on some other mechanism in the system to get
information about the locked up CPUs.  This could be support for NMI
backtraces like [1], it could be a mechanism for printing the PC of locked
CPUs at panic time like [2] / [3], or it could be something else.  Even
though that means we still rely on arch-specific code, this arch-specific
code seems to often be implemented even on architectures that don't have a
hardlockup detector.

This style of hardlockup detector originated in some downstream Android
trees and has been rebased on / carried in ChromeOS trees for quite a long
time for use on arm and arm64 boards.  Historically on these boards we've
leveraged mechanism [2] / [3] to get information about hung CPUs, but we
could move to [1].

Although the original motivation for the buddy system was for use on
systems without an arch-specific hardlockup detector, it can still be
useful to use even on systems that _do_ have an arch-specific hardlockup
detector.  On x86, for instance, there is a 24-part patch series [4] in
progress switching the arch-specific hard lockup detector from a scarce
perf counter to a less-scarce hardware resource.  Potentially the buddy
system could be a simpler alternative to free up the perf counter but
still get hard lockup detection.

Overall, pros (+) and cons (-) of the buddy system compared to an
arch-specific hardlockup detector (which might be implemented using
perf):
+ The buddy system is usable on systems that don't have an
  arch-specific hardlockup detector, like arm32 and arm64 (though it's
  being worked on for arm64 [5]).
+ The buddy system may free up scarce hardware resources.
+ If a CPU totally goes out to lunch (can't process NMIs) the buddy
  system could still detect the problem (though it would be unlikely
  to be able to get a stack trace).
+ The buddy system uses the same timer function to pet the hardlockup
  detector on the running CPU as it uses to detect hardlockups on
  other CPUs. Compared to other hardlockup detectors, this means it
  generates fewer interrupts and thus is likely better able to let
  CPUs stay idle longer.
- If all CPUs are hard locked up at the same time the buddy system
  can't detect it.
- If we don't have SMP we can't use the buddy system.
- The buddy system needs an arch-specific mechanism (possibly NMI
  backtrace) to get info about the locked up CPU.

[1] https://lore.kernel.org/r/20230419225604.21204-1-dianders@chromium.org
[2] https://issuetracker.google.com/172213129
[3] https://docs.kernel.org/trace/coresight/coresight-cpu-debug.html
[4] https://lore.kernel.org/lkml/20230301234753.28582-1-ricardo.neri-calderon@linux.intel.com/
[5] https://lore.kernel.org/linux-arm-kernel/20220903093415.15850-1-lecopzer.chen@mediatek.com/

Link: https://lkml.kernel.org/r/20230519101840.v5.14.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:21 -07:00
Douglas Anderson d9b3629ade watchdog/hardlockup: have the perf hardlockup use __weak functions more cleanly
The fact that there watchdog_hardlockup_enable(),
watchdog_hardlockup_disable(), and watchdog_hardlockup_probe() are
declared __weak means that the configured hardlockup detector can define
non-weak versions of those functions if it needs to.  Instead of doing
this, the perf hardlockup detector hooked itself into the default __weak
implementation, which was a bit awkward.  Clean this up.

From comments, it looks as if the original design was done because the
__weak function were expected to implemented by the architecture and not
by the configured hardlockup detector.  This got awkward when we tried to
add the buddy lockup detector which was not arch-specific but wanted to
hook into those same functions.

This is not expected to have any functional impact.

Link: https://lkml.kernel.org/r/20230519101840.v5.13.I847d9ec852449350997ba00401d2462a9cb4302b@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:21 -07:00
Douglas Anderson df95d3085c watchdog/hardlockup: rename some "NMI watchdog" constants/function
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 <dianders@chromium.org>
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:20 -07:00
Douglas Anderson ed92e1ef52 watchdog/hardlockup: move perf hardlockup watchdog petting to watchdog.c
In preparation for the buddy hardlockup detector, which wants the same
petting logic as the current perf hardlockup detector, move the code to
watchdog.c.  While doing this, rename the global variable to match others
nearby.  As part of this change we have to change the code to account for
the fact that the CPU we're running on might be different than the one
we're checking.

Currently the code in watchdog.c is guarded by
CONFIG_HARDLOCKUP_DETECTOR_PERF, which makes this change seem silly. 
However, a future patch will change this.

Link: https://lkml.kernel.org/r/20230519101840.v5.11.I00dfd6386ee00da25bf26d140559a41339b53e57@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:20 -07:00
Douglas Anderson 77c12fc959 watchdog/hardlockup: add a "cpu" param to watchdog_hardlockup_check()
In preparation for the buddy hardlockup detector where the CPU checking
for lockup might not be the currently running CPU, add a "cpu" parameter
to watchdog_hardlockup_check().

As part of this change, make hrtimer_interrupts an atomic_t since now the
CPU incrementing the value and the CPU reading the value might be
different.  Technially this could also be done with just READ_ONCE and
WRITE_ONCE, but atomic_t feels a little cleaner in this case.

While hrtimer_interrupts is made atomic_t, we change
hrtimer_interrupts_saved from "unsigned long" to "int".  The "int" is
needed to match the data type backing atomic_t for hrtimer_interrupts. 
Even if this changes us from 64-bits to 32-bits (which I don't think is
true for most compilers), it doesn't really matter.  All we ever do is
increment it every few seconds and compare it to an old value so 32-bits
is fine (even 16-bits would be).  The "signed" vs "unsigned" also doesn't
matter for simple equality comparisons.

hrtimer_interrupts_saved is _not_ switched to atomic_t nor even accessed
with READ_ONCE / WRITE_ONCE.  The hrtimer_interrupts_saved is always
consistently accessed with the same CPU.  NOTE: with the upcoming "buddy"
detector there is one special case.  When a CPU goes offline/online then
we can change which CPU is the one to consistently access a given instance
of hrtimer_interrupts_saved.  We still can't end up with a partially
updated hrtimer_interrupts_saved, however, because we end up petting all
affected CPUs to make sure the new and old CPU can't end up somehow
read/write hrtimer_interrupts_saved at the same time.

Link: https://lkml.kernel.org/r/20230519101840.v5.10.I3a7d4dd8c23ac30ee0b607d77feb6646b64825c0@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:20 -07:00
Douglas Anderson 1610611aad watchdog/hardlockup: style changes to watchdog_hardlockup_check() / is_hardlockup()
These are tiny style changes:
- Add a blank line before a "return".
- Renames two globals to use the "watchdog_hardlockup" prefix.
- Store processor id in "unsigned int" rather than "int".
- Minor comment rewording.
- Use "else" rather than extra returns since it seemed more symmetric.

Link: https://lkml.kernel.org/r/20230519101840.v5.9.I818492c326b632560b09f20d2608455ecf9d3650@changeid
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:20 -07:00
Douglas Anderson 81972551df watchdog/hardlockup: move perf hardlockup checking/panic to common watchdog.c
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 <dianders@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:19 -07:00
Lecopzer Chen 730211182e watchdog/hardlockup: change watchdog_nmi_enable() to void
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 <kernelfans@gmail.com>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:18 -07:00
Lecopzer Chen 810b560e89 watchdog: remove WATCHDOG_DEFAULT
No reference to WATCHDOG_DEFAULT, remove it.

Link: https://lkml.kernel.org/r/20230519101840.v5.3.I6a729209a1320e0ad212176e250ff945b8f91b2a@changeid
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Colin Cross <ccross@android.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Tzung-Bi Shih <tzungbi@chromium.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:18 -07:00
Linus Torvalds cae4199f93 powerpc updates for 6.0
- Add support for syscall stack randomization.
 
  - Add support for atomic operations to the 32 & 64-bit BPF JIT.
 
  - Full support for KASAN on 64-bit Book3E.
 
  - Add a watchdog driver for the new PowerVM hypervisor watchdog.
 
  - Add a number of new selftests for the Power10 PMU support.
 
  - Add a driver for the PowerVM Platform KeyStore.
 
  - Increase the NMI watchdog timeout during live partition migration, to avoid timeouts
    due to increased memory access latency.
 
  - Add support for using the 'linux,pci-domain' device tree property for PCI domain
    assignment.
 
  - Many other small features and fixes.
 
 Thanks to: Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira Rajeev, Bagas
 Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas, Greg Kroah-Hartman, Greg Kurz,
 Haowen Bai, Hari Bathini, Jason A. Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg
 Haefliger, Kajol Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
 Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch, Naveen N. Rao, Nayna
 Jain, Nicholas Piggin, Ning Qiang, Pali Rohár, Petr Mladek, Rashmica Gupta, Sachin Sant,
 Scott Cheloha, Segher Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
 Jianfeng, Zhouyi Zhou.
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Merge tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

 - Add support for syscall stack randomization

 - Add support for atomic operations to the 32 & 64-bit BPF JIT

 - Full support for KASAN on 64-bit Book3E

 - Add a watchdog driver for the new PowerVM hypervisor watchdog

 - Add a number of new selftests for the Power10 PMU support

 - Add a driver for the PowerVM Platform KeyStore

 - Increase the NMI watchdog timeout during live partition migration, to
   avoid timeouts due to increased memory access latency

 - Add support for using the 'linux,pci-domain' device tree property for
   PCI domain assignment

 - Many other small features and fixes

Thanks to Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira
Rajeev, Bagas Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas,
Greg Kroah-Hartman, Greg Kurz, Haowen Bai, Hari Bathini, Jason A.
Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg Haefliger, Kajol
Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch,
Naveen N.  Rao, Nayna Jain, Nicholas Piggin, Ning Qiang, Pali Rohár,
Petr Mladek, Rashmica Gupta, Sachin Sant, Scott Cheloha, Segher
Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
Jianfeng, and Zhouyi Zhou.

* tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (191 commits)
  powerpc/64e: Fix kexec build error
  EDAC/ppc_4xx: Include required of_irq header directly
  powerpc/pci: Fix PHB numbering when using opal-phbid
  powerpc/64: Init jump labels before parse_early_param()
  selftests/powerpc: Avoid GCC 12 uninitialised variable warning
  powerpc/cell/axon_msi: Fix refcount leak in setup_msi_msg_address
  powerpc/xive: Fix refcount leak in xive_get_max_prio
  powerpc/spufs: Fix refcount leak in spufs_init_isolated_loader
  powerpc/perf: Include caps feature for power10 DD1 version
  powerpc: add support for syscall stack randomization
  powerpc: Move system_call_exception() to syscall.c
  powerpc/powernv: rename remaining rng powernv_ functions to pnv_
  powerpc/powernv/kvm: Use darn for H_RANDOM on Power9
  powerpc/powernv: Avoid crashing if rng is NULL
  selftests/powerpc: Fix matrix multiply assist test
  powerpc/signal: Update comment for clarity
  powerpc: make facility_unavailable_exception 64s
  powerpc/platforms/83xx/suspend: Remove write-only global variable
  powerpc/platforms/83xx/suspend: Prevent unloading the driver
  powerpc/platforms/83xx/suspend: Reorder to get rid of a forward declaration
  ...
2022-08-06 16:38:17 -07:00
Laurent Dufour 7c56a8733d watchdog: export lockup_detector_reconfigure
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 <ldufour@linux.ibm.com>
[mpe: Squash in build fix from Laurent, reported by Sachin]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220713154729.80789-3-ldufour@linux.ibm.com
2022-07-27 21:35:32 +10:00
Petr Mladek 51889d225c Merge branch 'rework/kthreads' into for-linus 2022-06-23 19:11:28 +02:00
Petr Mladek 07a22b6194 Revert "printk: add functions to prefer direct printing"
This reverts commit 2bb2b7b57f.

The testing of 5.19 release candidates revealed missing synchronization
between early and regular console functionality.

It would be possible to start the console kthreads later as a workaround.
But it is clear that console lock serialized console drivers between
each other. It opens a big area of possible problems that were not
considered by people involved in the development and review.

printk() is crucial for debugging kernel issues and console output is
very important part of it. The number of consoles is huge and a proper
review would take some time. As a result it need to be reverted for 5.19.

Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220623145157.21938-7-pmladek@suse.com
2022-06-23 18:41:40 +02:00
Linus Torvalds 6f664045c8 Not a lot of material this cycle. Many singleton patches against various
subsystems.   Most notably some maintenance work in ocfs2 and initramfs.
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Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc updates from Andrew Morton:
 "The non-MM patch queue for this merge window.

  Not a lot of material this cycle. Many singleton patches against
  various subsystems. Most notably some maintenance work in ocfs2
  and initramfs"

* tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits)
  kcov: update pos before writing pc in trace function
  ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock
  ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
  fs/ntfs: remove redundant variable idx
  fat: remove time truncations in vfat_create/vfat_mkdir
  fat: report creation time in statx
  fat: ignore ctime updates, and keep ctime identical to mtime in memory
  fat: split fat_truncate_time() into separate functions
  MAINTAINERS: add Muchun as a memcg reviewer
  proc/sysctl: make protected_* world readable
  ia64: mca: drop redundant spinlock initialization
  tty: fix deadlock caused by calling printk() under tty_port->lock
  relay: remove redundant assignment to pointer buf
  fs/ntfs3: validate BOOT sectors_per_clusters
  lib/string_helpers: fix not adding strarray to device's resource list
  kernel/crash_core.c: remove redundant check of ck_cmdline
  ELF, uapi: fixup ELF_ST_TYPE definition
  ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()
  ipc: update semtimedop() to use hrtimer
  ipc/sem: remove redundant assignments
  ...
2022-05-27 11:22:03 -07:00
Rasmus Villemoes 67fca000e1 lib/Kconfig.debug: remove more CONFIG_..._VALUE indirections
As in "kernel/panic.c: remove CONFIG_PANIC_ON_OOPS_VALUE indirection",
use the IS_ENABLED() helper rather than having a hidden config option.

Link: https://lkml.kernel.org/r/20220321121301.1389693-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-04-29 14:38:00 -07:00
John Ogness 2bb2b7b57f printk: add functions to prefer direct printing
Once kthread printing is available, console printing will no longer
occur in the context of the printk caller. However, there are some
special contexts where it is desirable for the printk caller to
directly print out kernel messages. Using pr_flush() to wait for
threaded printers is only possible if the caller is in a sleepable
context and the kthreads are active. That is not always the case.

Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit()
functions to explicitly (and globally) activate/deactivate preferred
direct console printing. The term "direct console printing" refers to
printing to all enabled consoles from the context of the printk
caller. The term "prefer" is used because this type of printing is
only best effort. If the console is currently locked or other
printers are already actively printing, the printk caller will need
to rely on the other contexts to handle the printing.

This preferred direct printing is how all printing has been handled
until now (unless it was explicitly deferred).

When kthread printing is introduced, there may be some unanticipated
problems due to kthreads being unable to flush important messages.
In order to minimize such risks, preferred direct printing is
activated for the primary important messages when the system
experiences general types of major errors. These are:

 - emergency reboot/shutdown
 - cpu and rcu stalls
 - hard and soft lockups
 - hung tasks
 - warn
 - sysrq

Note that since kthread printing does not yet exist, no behavior
changes result from this commit. This is only implementing the
counter and marking the various places where preferred direct
printing is active.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de
2022-04-22 21:30:58 +02:00
Frederic Weisbecker 04d4e665a6 sched/isolation: Use single feature type while referring to housekeeping cpumask
Refer to housekeeping APIs using single feature types instead of flags.
This prevents from passing multiple isolation features at once to
housekeeping interfaces, which soon won't be possible anymore as each
isolation features will have their own cpumask.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
2022-02-16 15:57:55 +01:00
Xiaoming Ni dd0693fdf0 watchdog: move watchdog sysctl interface to watchdog.c
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic of proc sysctl.

So, move the watchdog syscl interface to watchdog.c.  Use
register_sysctl() to register the sysctl interface to avoid merge
conflicts when different features modify sysctl.c at the same time.

[mcgrof@kernel.org: justify the move on the commit log]

Link: https://lkml.kernel.org/r/20211123202347.818157-5-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-22 08:33:34 +02:00
Wang Qing b124ac45bd kernel: watchdog: modify the explanation related to watchdog thread
The watchdog thread has been replaced by cpu_stop_work, modify the
explanation related.

Link: https://lkml.kernel.org/r/1619687073-24686-2-git-send-email-wangqing@vivo.com
Signed-off-by: Wang Qing <wangqing@vivo.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Cc: Qais Yousef <qais.yousef@arm.com>
Cc: Santosh Sivaraj <santosh@fossix.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29 10:53:46 -07:00
Petr Mladek 0f90b88dbc watchdog: reliable handling of timestamps
Commit 9bf3bc949f ("watchdog: cleanup handling of false positives")
tried to handle a virtual host stopped by the host a more
straightforward and cleaner way.

But it introduced a risk of false softlockup reports.  The virtual host
might be stopped at any time, for example between
kvm_check_and_clear_guest_paused() and is_softlockup().  As a result,
is_softlockup() might read the updated jiffies and detects a softlockup.

A solution might be to put back kvm_check_and_clear_guest_paused() after
is_softlockup() and detect it.  But it would put back the cycle that
complicates the logic.

In fact, the handling of all the timestamps is not reliable.  The code
does not guarantee when and how many times the timestamps are read.  For
example, "period_ts" might be touched anytime also from NMI and re-read in
is_softlockup().  It works just by chance.

Fix all the problems by making the code even more explicit.

1. Make sure that "now" and "period_ts" timestamps are read only once.
   They might be changed at anytime by NMI or when the virtual guest is
   stopped by the host.  Note that "now" timestamp does this implicitly
   because "jiffies" is marked volatile.

2. "now" time must be read first.  The state of "period_ts" will
   decide whether it will be used or the period will get restarted.

3. kvm_check_and_clear_guest_paused() must be called before reading
   "period_ts".  It touches the variable when the guest was stopped.

As a result, "now" timestamp is used only when the watchdog was not
touched and the guest not stopped in the meantime.  "period_ts" is
restarted in all other situations.

Link: https://lkml.kernel.org/r/YKT55gw+RZfyoFf7@alley
Fixes: 9bf3bc949f ("watchdog: cleanup handling of false positives")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-22 15:09:07 -10:00
Petr Mladek 9bf3bc949f watchdog: cleanup handling of false positives
Commit d6ad3e286d ("softlockup: Add sched_clock_tick() to avoid kernel
warning on kgdb resume") introduced touch_softlockup_watchdog_sync().

It solved a problem when the watchdog was touched in an atomic context,
the timer callback was proceed right after releasing interrupts, and the
local clock has not been updated yet.  In this case, sched_clock_tick()
was called in watchdog_timer_fn() before updating the timer.

So far so good.

Later commit 5d1c0f4a80 ("watchdog: add check for suspended vm in
softlockup detector") added two kvm_check_and_clear_guest_paused()
calls.  They touch the watchdog when the guest has been sleeping.

The code makes my head spin around.

Scenario 1:

    + guest did sleep:
	+ PVCLOCK_GUEST_STOPPED is set

    + 1st watchdog_timer_fn() invocation:
	+ the watchdog is not touched yet
	+ is_softlockup() returns too big delay
	+ kvm_check_and_clear_guest_paused():
	   + clear PVCLOCK_GUEST_STOPPED
	   + call touch_softlockup_watchdog_sync()
		+ set SOFTLOCKUP_DELAY_REPORT
		+ set softlockup_touch_sync
	+ return from the timer callback

      + 2nd watchdog_timer_fn() invocation:

	+ call sched_clock_tick() even though it is not needed.
	  The timer callback was invoked again only because the clock
	  has already been updated in the meantime.

	+ call kvm_check_and_clear_guest_paused() that does nothing
	  because PVCLOCK_GUEST_STOPPED has been cleared already.

	+ call update_report_ts() and return. This is fine. Except
	  that sched_clock_tick() might allow to set it already
	  during the 1st invocation.

Scenario 2:

	+ guest did sleep

	+ 1st watchdog_timer_fn() invocation
	    + same as in 1st scenario

	+ guest did sleep again:
	    + set PVCLOCK_GUEST_STOPPED again

	+ 2nd watchdog_timer_fn() invocation
	    + SOFTLOCKUP_DELAY_REPORT is set from 1st invocation
	    + call sched_clock_tick()
	    + call kvm_check_and_clear_guest_paused()
		+ clear PVCLOCK_GUEST_STOPPED
		+ call touch_softlockup_watchdog_sync()
		    + set SOFTLOCKUP_DELAY_REPORT
		    + set softlockup_touch_sync
	    + call update_report_ts() (set real timestamp immediately)
	    + return from the timer callback

	+ 3rd watchdog_timer_fn() invocation
	    + timestamp is set from 2nd invocation
	    + softlockup_touch_sync is set but not checked because
	      the real timestamp is already set

Make the code more straightforward:

1. Always call kvm_check_and_clear_guest_paused() at the very
   beginning to handle PVCLOCK_GUEST_STOPPED. It touches the watchdog
   when the quest did sleep.

2. Handle the situation when the watchdog has been touched
   (SOFTLOCKUP_DELAY_REPORT is set).

   Call sched_clock_tick() when touch_*sync() variant was used. It makes
   sure that the timestamp will be up to date even when it has been
   touched in atomic context or quest did sleep.

As a result, kvm_check_and_clear_guest_paused() is called on a single
location.  And the right timestamp is always set when returning from the
timer callback.

Link: https://lkml.kernel.org/r/20210311122130.6788-7-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:36 -07:00
Petr Mladek 9f113bf760 watchdog: fix barriers when printing backtraces from all CPUs
Any parallel softlockup reports are skipped when one CPU is already
printing backtraces from all CPUs.

The exclusive rights are synchronized using one bit in
soft_lockup_nmi_warn.  There is also one memory barrier that does not make
much sense.

Use two barriers on the right location to prevent mixing two reports.

[pmladek@suse.com: use bit lock operations to prevent multiple soft-lockup reports]
  Link: https://lkml.kernel.org/r/YFSVsLGVWMXTvlbk@alley

Link: https://lkml.kernel.org/r/20210311122130.6788-6-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:36 -07:00
Petr Mladek 1bc503cb4a watchdog/softlockup: remove logic that tried to prevent repeated reports
The softlockup detector does some gymnastic with the variable
soft_watchdog_warn.  It was added by the commit 58687acba5
("lockup_detector: Combine nmi_watchdog and softlockup detector").

The purpose is not completely clear.  There are the following clues.  They
describe the situation how it looked after the above mentioned commit:

  1. The variable was checked with a comment "only warn once".

  2. The variable was set when softlockup was reported. It was cleared
     only when the CPU was not longer in the softlockup state.

  3. watchdog_touch_ts was not explicitly updated when the softlockup
     was reported. Without this variable, the report would normally
     be printed again during every following watchdog_timer_fn()
     invocation.

The logic has got even more tangled up by the commit ed235875e2
("kernel/watchdog.c: print traces for all cpus on lockup detection").
After this commit, soft_watchdog_warn is set only when
softlockup_all_cpu_backtrace is enabled.  But multiple reports from all
CPUs are prevented by a new variable soft_lockup_nmi_warn.

Conclusion:

The variable probably never worked as intended.  In each case, it has not
worked last many years because the softlockup was reported repeatedly
after the full period defined by watchdog_thresh.

The reason is that watchdog gets touched in many known slow paths, for
example, in printk_stack_address().  This code is called also when
printing the softlockup report.  It means that the watchdog timestamp gets
updated after each report.

Solution:

Simply remove the logic. People want the periodic report anyway.

Link: https://lkml.kernel.org/r/20210311122130.6788-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:36 -07:00
Petr Mladek fef06efc2e watchdog/softlockup: report the overall time of softlockups
The softlockup detector currently shows the time spent since the last
report.  As a result it is not clear whether a CPU is infinitely hogged by
a single task or if it is a repeated event.

The situation can be simulated with a simply busy loop:

	while (true)
	      cpu_relax();

The softlockup detector produces:

[  168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[  196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[  236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865]

But it should be, something like:

[  480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943]
[  508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943]
[  548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943]
[  576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943]

For the better output, add an additional timestamp of the last report.
Only this timestamp is reset when the watchdog is intentionally touched
from slow code paths or when printing the report.

Link: https://lkml.kernel.org/r/20210311122130.6788-4-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:36 -07:00
Petr Mladek c9ad17c991 watchdog: explicitly update timestamp when reporting softlockup
The softlockup situation might stay for a long time or even forever.  When
it happens, the softlockup debug messages are printed in regular intervals
defined by get_softlockup_thresh().

There is a mystery.  The repeated message is printed after the full
interval that is defined by get_softlockup_thresh().  But the timer
callback is called more often as defined by sample_period.  The code looks
like the soflockup should get reported in every sample_period when it was
once behind the thresh.

It works only by chance.  The watchdog is touched when printing the stall
report, for example, in printk_stack_address().

Make the behavior clear and predictable by explicitly updating the
timestamp in watchdog_timer_fn() when the report gets printed.

Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:35 -07:00
Petr Mladek 7c0012f522 watchdog: rename __touch_watchdog() to a better descriptive name
Patch series "watchdog/softlockup: Report overall time and some cleanup", v2.

I dug deep into the softlockup watchdog history when time permitted this
year.  And reworked the patchset that fixed timestamps and cleaned up the
code[2].

I split it into very small steps and did even more code clean up.  The
result looks quite strightforward and I am pretty confident with the
changes.

[1] v2: https://lore.kernel.org/r/20201210160038.31441-1-pmladek@suse.com
[2] v1: https://lore.kernel.org/r/20191024114928.15377-1-pmladek@suse.com

This patch (of 6):

There are many touch_*watchdog() functions.  They are called in situations
where the watchdog could report false positives or create unnecessary
noise.  For example, when CPU is entering idle mode, a virtual machine is
stopped, or a lot of messages are printed in the atomic context.

These functions set SOFTLOCKUP_RESET instead of a real timestamp.  It
allows to call them even in a context where jiffies might be outdated.
For example, in an atomic context.

The real timestamp is set by __touch_watchdog() that is called from the
watchdog timer callback.

Rename this callback to update_touch_ts().  It better describes the effect
and clearly distinguish is from the other touch_*watchdog() functions.

Another motivation is that two timestamps are going to be used.  One will
be used for the total softlockup time.  The other will be used to measure
time since the last report.  The new function name will help to
distinguish which timestamp is being updated.

Link: https://lkml.kernel.org/r/20210311122130.6788-1-pmladek@suse.com
Link: https://lkml.kernel.org/r/20210311122130.6788-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-04-30 11:20:35 -07:00
Wang Qing 89e28ce60c workqueue/watchdog: Make unbound workqueues aware of touch_softlockup_watchdog()
84;0;0c84;0;0c
There are two workqueue-specific watchdog timestamps:

    + @wq_watchdog_touched_cpu (per-CPU) updated by
      touch_softlockup_watchdog()

    + @wq_watchdog_touched (global) updated by
      touch_all_softlockup_watchdogs()

watchdog_timer_fn() checks only the global @wq_watchdog_touched for
unbound workqueues. As a result, unbound workqueues are not aware
of touch_softlockup_watchdog(). The watchdog might report a stall
even when the unbound workqueues are blocked by a known slow code.

Solution:
touch_softlockup_watchdog() must touch also the global @wq_watchdog_touched
timestamp.

The global timestamp can no longer be used for bound workqueues because
it is now updated from all CPUs. Instead, bound workqueues have to check
only @wq_watchdog_touched_cpu and these timestamps have to be updated for
all CPUs in touch_all_softlockup_watchdogs().

Beware:
The change might cause the opposite problem. An unbound workqueue
might get blocked on CPU A because of a real softlockup. The workqueue
watchdog would miss it when the timestamp got touched on CPU B.

It is acceptable because softlockups are detected by softlockup
watchdog. The workqueue watchdog is there to detect stalls where
a work never finishes, for example, because of dependencies of works
queued into the same workqueue.

V3:
- Modify the commit message clearly according to Petr's suggestion.

Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2021-04-04 13:26:49 -04:00
Santosh Sivaraj e7e046155a kernel/watchdog: fix watchdog_allowed_mask not used warning
Define watchdog_allowed_mask only when SOFTLOCKUP_DETECTOR is enabled.

Fixes: 7feeb9cd4f ("watchdog/sysctl: Clean up sysctl variable name space")
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20201106015025.1281561-1-santosh@fossix.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-14 11:26:03 -08:00
Guilherme G. Piccoli f117955a22 kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases
After a recent change introduced by Vlastimil's series [0], kernel is
able now to handle sysctl parameters on kernel command line; also, the
series introduced a simple infrastructure to convert legacy boot
parameters (that duplicate sysctls) into sysctl aliases.

This patch converts the watchdog parameters softlockup_panic and
{hard,soft}lockup_all_cpu_backtrace to use the new alias infrastructure.
It fixes the documentation too, since the alias only accepts values 0 or
1, not the full range of integers.

We also took the opportunity here to improve the documentation of the
previously converted hung_task_panic (see the patch series [0]) and put
the alias table in alphabetical order.

[0] http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Link: http://lkml.kernel.org/r/20200507214624.21911-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08 11:05:56 -07:00
Christoph Hellwig 32927393dc sysctl: pass kernel pointers to ->proc_handler
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 <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-04-27 02:07:40 -04:00
Thomas Gleixner 11e31f608b watchdog/softlockup: Enforce that timestamp is valid on boot
Robert reported that during boot the watchdog timestamp is set to 0 for one
second which is the indicator for a watchdog reset.

The reason for this is that the timestamp is in seconds and the time is
taken from sched clock and divided by ~1e9. sched clock starts at 0 which
means that for the first second during boot the watchdog timestamp is 0,
i.e. reset.

Use ULONG_MAX as the reset indicator value so the watchdog works correctly
right from the start. ULONG_MAX would only conflict with a real timestamp
if the system reaches an uptime of 136 years on 32bit and almost eternity
on 64bit.

Reported-by: Robert Richter <rrichter@marvell.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/87o8v3uuzl.fsf@nanos.tec.linutronix.de
2020-01-17 11:19:22 +01:00
Petr Mladek 3a51449b79 watchdog/softlockup: Remove obsolete check of last reported task
commit 9cf57731b6 ("watchdog/softlockup: Replace "watchdog/%u" threads
 with cpu_stop_work") ensures that the watchdog is reliably touched during
a task switch.

As a result the check for an unnoticed task switch is not longer needed.

Remove the relevant code, which effectively reverts commit b1a8de1f53
("softlockup: make detector be aware of task switch of processes hogging
cpu")

Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Ziljstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20191024114928.15377-2-pmladek@suse.com
2020-01-16 14:52:48 +01:00
Jisheng Zhang d129479f1f watchdog: Remove soft_lockup_hrtimer_cnt and related code
After commit 9cf57731b6 ("watchdog/softlockup: Replace "watchdog/%u"
threads with cpu_stop_work"), the percpu soft_lockup_hrtimer_cnt is
not used any more, so remove it and related code.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191218131720.4146aea2@xhacker.debian
2020-01-16 12:25:51 +01:00
Sebastian Andrzej Siewior d2ab4cf494 watchdog: Mark watchdog_hrtimer to expire in hard interrupt context
The watchdog hrtimer must expire in hard interrupt context even on
PREEMPT_RT=y kernels as otherwise the hard/softlockup detection logic would
not work.

No functional change.

[ tglx: Split out from larger combo patch. Added changelog ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.262895510@linutronix.de
2019-08-01 20:51:20 +02:00
Arash Fotouhi 76e1552466 watchdog: Fix typo in comment
Signed-off-by: Arash Fotouhi <arash@arashfotouhi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: loberman@redhat.com
Cc: vincent.whitchurch@axis.com
Link: http://lkml.kernel.org/r/1553308112-3513-1-git-send-email-arash@arashfotouhi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-18 14:05:51 +02:00
Thomas Gleixner 7dd4761711 watchdog: Respect watchdog cpumask on CPU hotplug
The rework of the watchdog core to use cpu_stop_work broke the watchdog
cpumask on CPU hotplug.

The watchdog_enable/disable() functions are now called unconditionally from
the hotplug callback, i.e. even on CPUs which are not in the watchdog
cpumask. As a consequence the watchdog can become unstoppable.

Only invoke them when the plugged CPU is in the watchdog cpumask.

Fixes: 9cf57731b6 ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work")
Reported-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903262245490.1789@nanos.tec.linutronix.de
2019-03-28 13:32:01 +01:00
Valdis Kletnieks 48084abf21 watchdog/core: Make variables static
sparse complains:
  CHECK   kernel/watchdog.c
kernel/watchdog.c:45:19: warning: symbol 'nmi_watchdog_available'
			 	  was not declared. Should it be static?
kernel/watchdog.c:47:16: warning: symbol 'watchdog_allowed_mask'
			 	  was not declared. Should it be static?

They're not referenced by name from anyplace else, make them static.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/7855.1552383228@turing-police
2019-03-22 13:40:17 +01:00
Laurence Oberman 1129505552 watchdog/core: Add watchdog_thresh command line parameter
The hard and soft lockup detector threshold has a default value of 10
seconds which can only be changed via sysctl.

During early boot lockup detection can trigger when noisy debugging emits
a large amount of messages to the console, but there is no way to set a
larger threshold on the kernel command line. The detector can only be
completely disabled.

Add a new watchdog_thresh= command line parameter to allow boot time
control over the threshold. It works in the same way as the sysctl and
affects both the soft and the hard lockup detectors.

Signed-off-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: rdunlap@infradead.org
Cc: prarit@redhat.com
Link: https://lkml.kernel.org/r/1541079018-13953-1-git-send-email-loberman@redhat.com
2018-11-01 14:33:35 +01:00
Vincent Whitchurch cb9d7fd51d watchdog: Mark watchdog touch functions as notrace
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 ce4f06dcbb ("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: ce4f06dcbb ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
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
2018-08-30 12:56:40 +02:00
Peter Zijlstra be45bf5395 watchdog/softlockup: Fix cpu_stop_queue_work() double-queue bug
When scheduling is delayed for longer than the softlockup interrupt
period it is possible to double-queue the cpu_stop_work, causing list
corruption.

Cure this by adding a completion to track the cpu_stop_work's
progress.

Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Rong Chen <rong.a.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9cf57731b6 ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work")
Link: http://lkml.kernel.org/r/20180713104208.GW2494@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-15 23:51:19 +02:00
Peter Zijlstra 9cf57731b6 watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work
Oleg suggested to replace the "watchdog/%u" threads with
cpu_stop_work. That removes one thread per CPU while at the same time
fixes softlockup vs SCHED_DEADLINE.

But more importantly, it does away with the single
smpboot_update_cpumask_percpu_thread() user, which allows
cleanups/shrinkage of the smpboot interface.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-03 09:20:43 +02:00