linux.git/kernel/reboot.c, branch v6.18.21

Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-04-01T17:06:52+00:00

Pull non-MM updates from Andrew Morton:

 - The series "powerpc/crash: use generic crashkernel reservation" from
   Sourabh Jain changes powerpc's kexec code to use more of the generic
   layers.

 - The series "get_maintainer: report subsystem status separately" from
   Vlastimil Babka makes some long-requested improvements to the
   get_maintainer output.

 - The series "ucount: Simplify refcounting with rcuref_t" from
   Sebastian Siewior cleans up and optimizing the refcounting in the
   ucount code.

 - The series "reboot: support runtime configuration of emergency
   hw_protection action" from Ahmad Fatoum improves the ability for a
   driver to perform an emergency system shutdown or reboot.

 - The series "Converge on using secs_to_jiffies() part two" from Easwar
   Hariharan performs further migrations from msecs_to_jiffies() to
   secs_to_jiffies().

 - The series "lib/interval_tree: add some test cases and cleanup" from
   Wei Yang permits more userspace testing of kernel library code, adds
   some more tests and performs some cleanups.

 - The series "hung_task: Dump the blocking task stacktrace" from Masami
   Hiramatsu arranges for the hung_task detector to dump the stack of
   the blocking task and not just that of the blocked task.

 - The series "resource: Split and use DEFINE_RES*() macros" from Andy
   Shevchenko provides some cleanups to the resource definition macros.

 - Plus the usual shower of singleton patches - please see the
   individual changelogs for details.

* tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits)
  mailmap: consolidate email addresses of Alexander Sverdlin
  fs/procfs: fix the comment above proc_pid_wchan()
  relay: use kasprintf() instead of fixed buffer formatting
  resource: replace open coded variant of DEFINE_RES()
  resource: replace open coded variants of DEFINE_RES_*_NAMED()
  resource: replace open coded variant of DEFINE_RES_NAMED_DESC()
  resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED()
  samples: add hung_task detector mutex blocking sample
  hung_task: show the blocker task if the task is hung on mutex
  kexec_core: accept unaccepted kexec segments' destination addresses
  watchdog/perf: optimize bytes copied and remove manual NUL-termination
  lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap()
  lib/interval_tree: skip the check before go to the right subtree
  lib/interval_tree: add test case for span iteration
  lib/interval_tree: add test case for interval_tree_iter_xxx() helpers
  lib/rbtree: add random seed
  lib/rbtree: split tests
  lib/rbtree: enable userland test suite for rbtree related data structure
  checkpatch: describe --min-conf-desc-length
  scripts/gdb/symbols: determine KASLR offset on s390
  ...

reboot: add support for configuring emergency hardware protection action

2025-03-17T06:24:14+00:00

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

In the general case, however, the driver detecting the issue can't know
what the appropriate course of action is and shouldn't be dictating the
policy of dealing with it.

Therefore, add a global hw_protection toggle that allows the user to
specify whether shutdown or reboot should be the default action when the
driver doesn't set policy.

This introduces no functional change yet as hw_protection_trigger() has no
callers, but these will be added in subsequent commits.

[arnd@arndb.de: hide unused hw_protection_attr]
  Link: https://lkml.kernel.org/r/20250224141849.1546019-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-7-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Cc: Benson Leung 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Mark Brown 
Cc: Matteo Croce 
Cc: Matti Vaittinen 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring (Arm) 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

reboot: indicate whether it is a HARDWARE PROTECTION reboot or shutdown

2025-03-17T06:24:13+00:00

It currently depends on the caller, whether we attempt a hardware
protection shutdown (poweroff) or a reboot.  A follow-up commit will make
this partially user-configurable, so it's a good idea to have the
emergency message clearly state whether the kernel is going for a reboot
or a shutdown.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-6-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Cc: Benson Leung 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Mark Brown 
Cc: Matteo Croce 
Cc: Matti Vaittinen 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring (Arm) 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

reboot: rename now misleading __hw_protection_shutdown symbols

2025-03-17T06:24:13+00:00

The __hw_protection_shutdown function name has become misleading since it
can cause either a shutdown (poweroff) or a reboot depending on its
argument.

To avoid further confusion, let's rename it, so it doesn't suggest that a
poweroff is all it can do.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-5-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Cc: Benson Leung 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Mark Brown 
Cc: Matteo Croce 
Cc: Matti Vaittinen 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring (Arm) 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

reboot: describe do_kernel_restart's cmd argument in kernel-doc

2025-03-17T06:24:13+00:00

A W=1 build rightfully complains about the function's kernel-doc being
incomplete.

Describe its single parameter to fix this.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-4-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Cc: Benson Leung 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Mark Brown 
Cc: Matteo Croce 
Cc: Matti Vaittinen 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring (Arm) 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

reboot: reboot, not shutdown, on hw_protection_reboot timeout

2025-03-17T06:24:13+00:00

hw_protection_shutdown() will kick off an orderly shutdown and if that
takes longer than a configurable amount of time, an emergency shutdown
will occur.

Recently, hw_protection_reboot() was added for those systems that don't
implement a proper shutdown and are better served by rebooting and having
the boot firmware worry about doing something about the critical
condition.

On timeout of the orderly reboot of hw_protection_reboot(), the system
would go into shutdown, instead of reboot.  This is not a good idea, as
going into shutdown was explicitly not asked for.

Fix this by always doing an emergency reboot if hw_protection_reboot() is
called and the orderly reboot takes too long.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-2-e1c09b090c0c@pengutronix.de
Fixes: 79fa723ba84c ("reboot: Introduce thermal_zone_device_critical_reboot()")
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Reviewed-by: Matti Vaittinen 
Cc: Benson Leung 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Mark Brown 
Cc: Matteo Croce 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring (Arm) 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

reboot: replace __hw_protection_shutdown bool action parameter with an enum

2025-03-17T06:24:13+00:00

Patch series "reboot: support runtime configuration of emergency
hw_protection action", v3.

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

This is inadequate in the general case though as a driver reporting e.g. 
an imminent power failure can't know whether a shutdown or a reboot would
be more appropriate for a given hardware platform.

To address this, this series adds a hw_protection kernel parameter and
sysfs toggle that can be used to change the action from the shutdown
default to reboot.  A new hw_protection_trigger API then makes use of this
default action.

My particular use case is unattended embedded systems that don't have
support for shutdown and that power on automatically when power is
supplied:

  - A brief power cycle gets detected by the driver
  - The kernel powers down the system and SoC goes into shutdown mode
  - Power is restored
  - The system remains oblivious to the restored power
  - System needs to be manually power cycled for a duration long enough
    to drain the capacitors

With this series, such systems can configure the kernel with
hw_protection=reboot to have the boot firmware worry about critical
conditions.


This patch (of 12):

Currently __hw_protection_shutdown() either reboots or shuts down the
system according to its shutdown argument.

To make the logic easier to follow, both inside __hw_protection_shutdown
and at caller sites, lets replace the bool parameter with an enum.

This will be extra useful, when in a later commit, a third action is added
to the enumeration.

No functional change.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-0-e1c09b090c0c@pengutronix.de
Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-1-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum 
Reviewed-by: Tzung-Bi Shih 
Cc: Benson Leung 
Cc: Mark Brown 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Guenter Roeck 
Cc: Jonathan Corbet 
Cc: Liam Girdwood 
Cc: Lukasz Luba 
Cc: Matteo Croce 
Cc: Matti Vaittinen 
Cc: "Rafael J. Wysocki" 
Cc: Rob Herring 
Cc: Rui Zhang 
Cc: Sascha Hauer 
Cc: "Serge E. Hallyn" 
Signed-off-by: Andrew Morton

Flush console log from kernel_power_off()

2025-03-05T02:44:29+00:00

Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output
and shutdown time, which hides shutdown-time RCU issues from rcutorture.
Therefore, make pr_flush() public and invoke it after then last print
in kernel_power_off().

[ paulmck: Apply John Ogness feedback. ]
[ paulmck: Appy Sebastian Andrzej Siewior feedback. ]
[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Paul E. McKenney 
Reviewed-by: John Ogness 
Reviewed-by: Petr Mladek 
Cc: Steven Rostedt 
Cc: Sergey Senozhatsky 
Link: https://lore.kernel.org/r/5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop
Signed-off-by: Boqun Feng

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37+00:00

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
    virtual patch

    @
    depends on !(file in "net")
    disable optional_qualifier
    @

    identifier table_name != {
      watchdog_hardlockup_sysctl,
      iwcm_ctl_table,
      ucma_ctl_table,
      memory_allocation_profiling_sysctls,
      loadpin_sysctl_table
    };
    @@

    + const
    struct ctl_table table_name [] = { ... };

sed:
    sed --in-place \
      -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
      kernel/utsname_sysctl.c

Reviewed-by: Song Liu 
Acked-by: Steven Rostedt (Google)  # for kernel/trace/
Reviewed-by: Martin K. Petersen  # SCSI
Reviewed-by: Darrick J. Wong  # xfs
Acked-by: Jani Nikula 
Acked-by: Corey Minyard 
Acked-by: Wei Liu 
Acked-by: Thomas Gleixner 
Reviewed-by: Bill O'Donnell 
Acked-by: Baoquan He 
Acked-by: Ashutosh Dixit 
Acked-by: Anna Schumaker 
Signed-off-by: Joel Granados

kernel/reboot: replace sprintf() with sysfs_emit()

2024-11-12T01:17:05+00:00

As Documentation/filesystems/sysfs.rst suggested, show() should only use
sysfs_emit() or sysfs_emit_at() when formatting the value to be returned
to user space.

No functional change intended.

Link: https://lkml.kernel.org/r/20241105094941.33739-1-zhangguopeng@kylinos.cn
Signed-off-by: zhangguopeng 
Cc: Daniel Lezcano 
Cc: Fabio Estevam 
Cc: Joel Granados 
Cc: Thomas Weißschuh 
Signed-off-by: Andrew Morton