Merge tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-mm updates from Andrew Morton:

 - Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in top-level
   directories

 - Douglas Anderson has added a new "buddy" mode to the hardlockup
   detector. It permits the detector to work on architectures which
   cannot provide the required interrupts, by having CPUs periodically
   perform checks on other CPUs

 - Zhen Lei has enhanced kexec's ability to support two crash regions

 - Petr Mladek has done a lot of cleanup on the hard lockup detector's
   Kconfig entries

 - And the usual bunch of singleton patches in various places

* tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits)
  kernel/time/posix-stubs.c: remove duplicated include
  ocfs2: remove redundant assignment to variable bit_off
  watchdog/hardlockup: fix typo in config HARDLOCKUP_DETECTOR_PREFER_BUDDY
  powerpc: move arch_trigger_cpumask_backtrace from nmi.h to irq.h
  devres: show which resource was invalid in __devm_ioremap_resource()
  watchdog/hardlockup: define HARDLOCKUP_DETECTOR_ARCH
  watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64
  watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific
  watchdog/hardlockup: declare arch_touch_nmi_watchdog() only in linux/nmi.h
  watchdog/hardlockup: make the config checks more straightforward
  watchdog/hardlockup: sort hardlockup detector related config values a logical way
  watchdog/hardlockup: move SMP barriers from common code to buddy code
  watchdog/buddy: simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY
  watchdog/buddy: don't copy the cpumask in watchdog_next_cpu()
  watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called
  watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog()
  watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy()
  watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick()
  watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
  watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails
  ...

1 files changed, 72 insertions, 12 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 376784ad3545..781f061ec0fa 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1035,27 +1035,30 @@ config BOOTPARAM_SOFTLOCKUP_PANIC
 
 	  Say N if unsure.
 
-config HARDLOCKUP_DETECTOR_PERF
+config HAVE_HARDLOCKUP_DETECTOR_BUDDY
 	bool
-	select SOFTLOCKUP_DETECTOR
+	depends on SMP
+	default y
 
 #
-# Enables a timestamp based low pass filter to compensate for perf based
-# hard lockup detection which runs too fast due to turbo modes.
+# Global switch whether to build a hardlockup detector at all. It is available
+# only when the architecture supports at least one implementation. There are
+# two exceptions. The hardlockup detector is never enabled on:
 #
-config HARDLOCKUP_CHECK_TIMESTAMP
-	bool
-
+#	s390: it reported many false positives there
 #
-# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
-# lockup detector rather than the perf based detector.
+#	sparc64: has a custom implementation which is not using the common
+#		hardlockup command line options and sysctl interface.
 #
 config HARDLOCKUP_DETECTOR
 	bool "Detect Hard Lockups"
-	depends on DEBUG_KERNEL && !S390
-	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
+	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
+	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
+	imply HARDLOCKUP_DETECTOR_PERF
+	imply HARDLOCKUP_DETECTOR_BUDDY
+	imply HARDLOCKUP_DETECTOR_ARCH
 	select LOCKUP_DETECTOR
-	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
+
 	help
 	  Say Y here to enable the kernel to act as a watchdog to detect
 	  hard lockups.
@@ -1065,6 +1068,63 @@ config HARDLOCKUP_DETECTOR
 	  chance to run.  The current stack trace is displayed upon detection
 	  and the system will stay locked up.
 
+#
+# Note that arch-specific variants are always preferred.
+#
+config HARDLOCKUP_DETECTOR_PREFER_BUDDY
+	bool "Prefer the buddy CPU hardlockup detector"
+	depends on HARDLOCKUP_DETECTOR
+	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
+	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
+	help
+	  Say Y here to prefer the buddy hardlockup detector over the perf one.
+
+	  With the buddy detector, each CPU uses its softlockup hrtimer
+	  to check that the next CPU is processing hrtimer interrupts by
+	  verifying that a counter is increasing.
+
+	  This hardlockup detector is useful on systems that don't have
+	  an arch-specific hardlockup detector or if resources needed
+	  for the hardlockup detector are better used for other things.
+
+config HARDLOCKUP_DETECTOR_PERF
+	bool
+	depends on HARDLOCKUP_DETECTOR
+	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
+	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
+	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
+
+config HARDLOCKUP_DETECTOR_BUDDY
+	bool
+	depends on HARDLOCKUP_DETECTOR
+	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
+	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
+	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
+	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
+
+config HARDLOCKUP_DETECTOR_ARCH
+	bool
+	depends on HARDLOCKUP_DETECTOR
+	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
+	help
+	  The arch-specific implementation of the hardlockup detector will
+	  be used.
+
+#
+# Both the "perf" and "buddy" hardlockup detectors count hrtimer
+# interrupts. This config enables functions managing this common code.
+#
+config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
+	bool
+	select SOFTLOCKUP_DETECTOR
+
+#
+# Enables a timestamp based low pass filter to compensate for perf based
+# hard lockup detection which runs too fast due to turbo modes.
+#
+config HARDLOCKUP_CHECK_TIMESTAMP
+	bool
+
 config BOOTPARAM_HARDLOCKUP_PANIC
 	bool "Panic (Reboot) On Hard Lockups"
 	depends on HARDLOCKUP_DETECTOR