linux-stable.git/kernel/power/suspend.c, branch v6.15 Linux kernel stable tree Merge tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux 2025-03-28T02:22:24+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-03-28T02:22:24+00:00 96050814a3f667eb28dabb78e7b3a7b06e5243e9 Pull printk updates from Petr Mladek: - New option "printk.debug_non_panic_cpus" allows to store printk messages from non-panic CPUs during panic. It might be useful when panic() fails. It is disabled by default because it increases the chance to see the messages printed before panic() and on the panic-CPU. - New build option "CONFIG_NULL_TTY_DEFAULT_CONSOLE" allows to build kernel without the virtual terminal support which prefers ttynull over serial console. - Do not unblank suspended consoles. - Some code clean up. * tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/panic: Add option to allow non-panic CPUs to write to the ring buffer. printk: Add an option to allow ttynull to be a default console device printk: Check CON_SUSPEND when unblanking a console printk: Rename console_start to console_resume printk: Rename console_stop to console_suspend printk: Rename resume_console to console_resume_all printk: Rename suspend_console to console_suspend_all 
Pull printk updates from Petr Mladek:

 - New option "printk.debug_non_panic_cpus" allows to store printk
   messages from non-panic CPUs during panic. It might be useful when
   panic() fails. It is disabled by default because it increases the
   chance to see the messages printed before panic() and on the
   panic-CPU.

 - New build option "CONFIG_NULL_TTY_DEFAULT_CONSOLE" allows to build
   kernel without the virtual terminal support which prefers ttynull
   over serial console.

 - Do not unblank suspended consoles.

 - Some code clean up.

* tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk/panic: Add option to allow non-panic CPUs to write to the ring buffer.
  printk: Add an option to allow ttynull to be a default console device
  printk: Check CON_SUSPEND when unblanking a console
  printk: Rename console_start to console_resume
  printk: Rename console_stop to console_suspend
  printk: Rename resume_console to console_resume_all
  printk: Rename suspend_console to console_suspend_all
PM: s2idle: Extend comment in s2idle_enter() 2025-03-12T20:14:53+00:00 Ulf Hansson ulf.hansson@linaro.org 2025-03-11T16:08:23+00:00 4b7d654258e0dd69a7d00be387b388f9d7544912 The s2idle_lock must be held while checking for a pending wakeup and while moving into S2IDLE_STATE_ENTER, to make sure a wakeup doesn't get lost. Let's extend the comment in the code to make this clear. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Link: https://patch.msgid.link/20250311160827.1129643-3-ulf.hansson@linaro.org [ rjw: Rewrote the new comment ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The s2idle_lock must be held while checking for a pending wakeup and while
moving into S2IDLE_STATE_ENTER, to make sure a wakeup doesn't get lost.
Let's extend the comment in the code to make this clear.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20250311160827.1129643-3-ulf.hansson@linaro.org
[ rjw: Rewrote the new comment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PM: s2idle: Drop redundant locks when entering s2idle 2025-03-12T20:14:53+00:00 Ulf Hansson ulf.hansson@linaro.org 2025-03-11T16:08:22+00:00 0f42194c6b22d687fd53c8aea5413cf976366672 The calls to cpus_read_lock|unlock() protects us from getting CPUS hotplugged, while entering suspend-to-idle. However, when s2idle_enter() is called we should be far beyond the point when CPUs may be hotplugged. Let's therefore simplify the code and drop the use of the lock. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Link: https://patch.msgid.link/20250311160827.1129643-2-ulf.hansson@linaro.org [ rjw: Rewrote the new comment ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
The calls to cpus_read_lock|unlock() protects us from getting CPUS
hotplugged, while entering suspend-to-idle. However, when s2idle_enter() is
called we should be far beyond the point when CPUs may be hotplugged.
Let's therefore simplify the code and drop the use of the lock.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://patch.msgid.link/20250311160827.1129643-2-ulf.hansson@linaro.org
[ rjw: Rewrote the new comment ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
printk: Rename resume_console to console_resume_all 2025-03-11T10:51:27+00:00 Marcos Paulo de Souza mpdesouza@suse.com 2025-02-26T19:59:02+00:00 63830aef74188354806ea3c9043dd3929c6e47f3 The function resume_console has a misleading name, since it resumes all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-2-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek <pmladek@suse.com> 
The function resume_console has a misleading name,  since it resumes all
consoles, so rename it accordingly.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-2-0b878577f2e6@suse.com
[pmladek@suse.com: Fixed typo in the commit message.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
printk: Rename suspend_console to console_suspend_all 2025-03-11T10:49:34+00:00 Marcos Paulo de Souza mpdesouza@suse.com 2025-02-26T19:59:01+00:00 e9cec4487cb789645a8c84b13a9ce54c2d89e3bb The function suspend_console has a misleading name, since it suspends all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-1-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek <pmladek@suse.com> 
The function suspend_console has a misleading name, since it suspends all
consoles, so rename it accordingly.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-1-0b878577f2e6@suse.com
[pmladek@suse.com: Fixed typo in the commit message.]
Signed-off-by: Petr Mladek <pmladek@suse.com>
PM: s2idle: Make sure CPUs will wakeup directly on resume 2024-04-08T13:36:54+00:00 Anna-Maria Behnsen anna-maria@linutronix.de 2024-04-08T07:02:23+00:00 3c89a068bfd0698a5478f4cf39493595ef757d5e s2idle works like a regular suspend with freezing processes and freezing devices. All CPUs except the control CPU go into idle. Once this is completed the control CPU kicks all other CPUs out of idle, so that they reenter the idle loop and then enter s2idle state. The control CPU then issues an swait() on the suspend state and therefore enters the idle loop as well. Due to being kicked out of idle, the other CPUs leave their NOHZ states, which means the tick is active and the corresponding hrtimer is programmed to the next jiffie. On entering s2idle the CPUs shut down their local clockevent device to prevent wakeups. The last CPU which enters s2idle shuts down its local clockevent and freezes timekeeping. On resume, one of the CPUs receives the wakeup interrupt, unfreezes timekeeping and its local clockevent and starts the resume process. At that point all other CPUs are still in s2idle with their clockevents switched off. They only resume when they are kicked by another CPU or after resuming devices and then receiving a device interrupt. That means there is no guarantee that all CPUs will wakeup directly on resume. As a consequence there is no guarantee that timers which are queued on those CPUs and should expire directly after resume, are handled. Also timer list timers which are remotely queued to one of those CPUs after resume will not result in a reprogramming IPI as the tick is active. Queueing a hrtimer will also not result in a reprogramming IPI because the first hrtimer event is already in the past. The recent introduction of the timer pull model (7ee988770326 ("timers: Implement the hierarchical pull model")) amplifies this problem, if the current migrator is one of the non woken up CPUs. When a non pinned timer list timer is queued and the queuing CPU goes idle, it relies on the still suspended migrator CPU to expire the timer which will happen by chance. The problem exists since commit 8d89835b0467 ("PM: suspend: Do not pause cpuidle in the suspend-to-idle path"). There the cpuidle_pause() call which in turn invoked a wakeup for all idle CPUs was moved to a later point in the resume process. This might not be reached or reached very late because it waits on a timer of a still suspended CPU. Address this by kicking all CPUs out of idle after the control CPU returns from swait() so that they resume their timers and restore consistent system state. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218641 Fixes: 8d89835b0467 ("PM: suspend: Do not pause cpuidle in the suspend-to-idle path") Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mario Limonciello <mario.limonciello@amd.com> Cc: 5.16+ <stable@kernel.org> # 5.16+ Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
s2idle works like a regular suspend with freezing processes and freezing
devices. All CPUs except the control CPU go into idle. Once this is
completed the control CPU kicks all other CPUs out of idle, so that they
reenter the idle loop and then enter s2idle state. The control CPU then
issues an swait() on the suspend state and therefore enters the idle loop
as well.

Due to being kicked out of idle, the other CPUs leave their NOHZ states,
which means the tick is active and the corresponding hrtimer is programmed
to the next jiffie.

On entering s2idle the CPUs shut down their local clockevent device to
prevent wakeups. The last CPU which enters s2idle shuts down its local
clockevent and freezes timekeeping.

On resume, one of the CPUs receives the wakeup interrupt, unfreezes
timekeeping and its local clockevent and starts the resume process. At that
point all other CPUs are still in s2idle with their clockevents switched
off. They only resume when they are kicked by another CPU or after resuming
devices and then receiving a device interrupt.

That means there is no guarantee that all CPUs will wakeup directly on
resume. As a consequence there is no guarantee that timers which are queued
on those CPUs and should expire directly after resume, are handled. Also
timer list timers which are remotely queued to one of those CPUs after
resume will not result in a reprogramming IPI as the tick is
active. Queueing a hrtimer will also not result in a reprogramming IPI
because the first hrtimer event is already in the past.

The recent introduction of the timer pull model (7ee988770326 ("timers:
Implement the hierarchical pull model")) amplifies this problem, if the
current migrator is one of the non woken up CPUs. When a non pinned timer
list timer is queued and the queuing CPU goes idle, it relies on the still
suspended migrator CPU to expire the timer which will happen by chance.

The problem exists since commit 8d89835b0467 ("PM: suspend: Do not pause
cpuidle in the suspend-to-idle path"). There the cpuidle_pause() call which
in turn invoked a wakeup for all idle CPUs was moved to a later point in
the resume process. This might not be reached or reached very late because
it waits on a timer of a still suspended CPU.

Address this by kicking all CPUs out of idle after the control CPU returns
from swait() so that they resume their timers and restore consistent system
state.

Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218641
Fixes: 8d89835b0467 ("PM: suspend: Do not pause cpuidle in the suspend-to-idle path")
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Cc: 5.16+ <stable@kernel.org> # 5.16+
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PM: suspend: Set mem_sleep_current during kernel command line setup 2024-02-29T19:33:00+00:00 Maulik Shah quic_mkshah@quicinc.com 2024-02-29T06:44:59+00:00 9bc4ffd32ef8943f5c5a42c9637cfd04771d021b psci_init_system_suspend() invokes suspend_set_ops() very early during bootup even before kernel command line for mem_sleep_default is setup. This leads to kernel command line mem_sleep_default=s2idle not working as mem_sleep_current gets changed to deep via suspend_set_ops() and never changes back to s2idle. Set mem_sleep_current along with mem_sleep_default during kernel command line setup as default suspend mode. Fixes: faf7ec4a92c0 ("drivers: firmware: psci: add system suspend support") CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Maulik Shah <quic_mkshah@quicinc.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
psci_init_system_suspend() invokes suspend_set_ops() very early during
bootup even before kernel command line for mem_sleep_default is setup.
This leads to kernel command line mem_sleep_default=s2idle not working
as mem_sleep_current gets changed to deep via suspend_set_ops() and never
changes back to s2idle.

Set mem_sleep_current along with mem_sleep_default during kernel command
line setup as default suspend mode.

Fixes: faf7ec4a92c0 ("drivers: firmware: psci: add system suspend support")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PM: sleep: stats: Define suspend_stats next to the code using it 2024-02-05T13:28:19+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2024-01-29T16:30:44+00:00 9ff544fa5f94fe07f99a36d2138075b322067546 It is not necessary to define struct suspend_stats in a header file and the suspend_stats variable in the core device system-wide PM code. They both can be defined in kernel/power/main.c, next to the sysfs and debugfs code accessing suspend_stats, which can be static. Modify the code in question in accordance with the above observation and replace the static inline functions manipulating suspend_stats with regular ones defined in kernel/power/main.c. While at it, move the enum suspend_stat_step to the end of suspend.h which is a more suitable place for it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> 
It is not necessary to define struct suspend_stats in a header file and the
suspend_stats variable in the core device system-wide PM code.  They both
can be defined in kernel/power/main.c, next to the sysfs and debugfs code
accessing suspend_stats, which can be static.

Modify the code in question in accordance with the above observation and
replace the static inline functions manipulating suspend_stats with
regular ones defined in kernel/power/main.c.

While at it, move the enum suspend_stat_step to the end of suspend.h which
is a more suitable place for it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
PM: sleep: stats: Use an array of step failure counters 2024-02-05T13:25:56+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2024-01-29T16:11:57+00:00 b730bab0b9c4204d7dda3f5bc8adf4292497fc39 Instead of using a set of individual struct suspend_stats fields representing suspend step failure counters, use an array of counters indexed by enum suspend_stat_step for this purpose, which allows dpm_save_failed_step() to increment the appropriate counter automatically, so that its callers don't need to do that directly. It also allows suspend_stats_show() to carry out a loop over the counters array to print their values. Because the counters cannot become negative, use unsigned int for representing them. The only user-observable impact of this change is a different ordering of entries in the suspend_stats debugfs file which is not expected to matter. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> 
Instead of using a set of individual struct suspend_stats fields
representing suspend step failure counters, use an array of counters
indexed by enum suspend_stat_step for this purpose, which allows
dpm_save_failed_step() to increment the appropriate counter
automatically, so that its callers don't need to do that directly.

It also allows suspend_stats_show() to carry out a loop over the
counters array to print their values.

Because the counters cannot become negative, use unsigned int for
representing them.

The only user-observable impact of this change is a different
ordering of entries in the suspend_stats debugfs file which is not
expected to matter.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Merge tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2022-10-10T16:10:28+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-10-10T16:10:28+00:00 30c999937f69abf935b0228b8411713737377d9e Pull scheduler updates from Ingo Molnar: "Debuggability: - Change most occurances of BUG_ON() to WARN_ON_ONCE() - Reorganize & fix TASK_ state comparisons, turn it into a bitmap - Update/fix misc scheduler debugging facilities Load-balancing & regular scheduling: - Improve the behavior of the scheduler in presence of lot of SCHED_IDLE tasks - in particular they should not impact other scheduling classes. - Optimize task load tracking, cleanups & fixes - Clean up & simplify misc load-balancing code Freezer: - Rewrite the core freezer to behave better wrt thawing and be simpler in general, by replacing PF_FROZEN with TASK_FROZEN & fixing/adjusting all the fallout. Deadline scheduler: - Fix the DL capacity-aware code - Factor out dl_task_is_earliest_deadline() & replenish_dl_new_period() - Relax/optimize locking in task_non_contending() Cleanups: - Factor out the update_current_exec_runtime() helper - Various cleanups, simplifications" * tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits) sched: Fix more TASK_state comparisons sched: Fix TASK_state comparisons sched/fair: Move call to list_last_entry() in detach_tasks sched/fair: Cleanup loop_max and loop_break sched/fair: Make sure to try to detach at least one movable task sched: Show PF_flag holes freezer,sched: Rewrite core freezer logic sched: Widen TAKS_state literals sched/wait: Add wait_event_state() sched/completion: Add wait_for_completion_state() sched: Add TASK_ANY for wait_task_inactive() sched: Change wait_task_inactive()s match_state freezer,umh: Clean up freezer/initrd interaction freezer: Have {,un}lock_system_sleep() save/restore flags sched: Rename task_running() to task_on_cpu() sched/fair: Cleanup for SIS_PROP sched/fair: Default to false in test_idle_cores() sched/fair: Remove useless check in select_idle_core() sched/fair: Avoid double search on same cpu sched/fair: Remove redundant check in select_idle_smt() ... 
Pull scheduler updates from Ingo Molnar:
 "Debuggability:

   - Change most occurances of BUG_ON() to WARN_ON_ONCE()

   - Reorganize & fix TASK_ state comparisons, turn it into a bitmap

   - Update/fix misc scheduler debugging facilities

  Load-balancing & regular scheduling:

   - Improve the behavior of the scheduler in presence of lot of
     SCHED_IDLE tasks - in particular they should not impact other
     scheduling classes.

   - Optimize task load tracking, cleanups & fixes

   - Clean up & simplify misc load-balancing code

  Freezer:

   - Rewrite the core freezer to behave better wrt thawing and be
     simpler in general, by replacing PF_FROZEN with TASK_FROZEN &
     fixing/adjusting all the fallout.

  Deadline scheduler:

   - Fix the DL capacity-aware code

   - Factor out dl_task_is_earliest_deadline() &
     replenish_dl_new_period()

   - Relax/optimize locking in task_non_contending()

  Cleanups:

   - Factor out the update_current_exec_runtime() helper

   - Various cleanups, simplifications"

* tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  sched: Fix more TASK_state comparisons
  sched: Fix TASK_state comparisons
  sched/fair: Move call to list_last_entry() in detach_tasks
  sched/fair: Cleanup loop_max and loop_break
  sched/fair: Make sure to try to detach at least one movable task
  sched: Show PF_flag holes
  freezer,sched: Rewrite core freezer logic
  sched: Widen TAKS_state literals
  sched/wait: Add wait_event_state()
  sched/completion: Add wait_for_completion_state()
  sched: Add TASK_ANY for wait_task_inactive()
  sched: Change wait_task_inactive()s match_state
  freezer,umh: Clean up freezer/initrd interaction
  freezer: Have {,un}lock_system_sleep() save/restore flags
  sched: Rename task_running() to task_on_cpu()
  sched/fair: Cleanup for SIS_PROP
  sched/fair: Default to false in test_idle_cores()
  sched/fair: Remove useless check in select_idle_core()
  sched/fair: Avoid double search on same cpu
  sched/fair: Remove redundant check in select_idle_smt()
  ...