cgroup/cpuset: Make cpuset hotplug processing synchronous

Since commit 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside
get_online_cpus()"), cpuset hotplug was done asynchronously via a work
fun

cgroup/cpuset: Make cpuset hotplug processing synchronous

Since commit 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside
get_online_cpus()"), cpuset hotplug was done asynchronously via a work
function. This is to avoid recursive locking of cgroup_mutex.

Since then, the cgroup locking scheme has changed quite a bit. A
cpuset_mutex was introduced to protect cpuset specific operations.
The cpuset_mutex is then replaced by a cpuset_rwsem. With commit
d74b27d63a8b ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock
order"), cpu_hotplug_lock is acquired before cpuset_rwsem. Later on,
cpuset_rwsem is reverted back to cpuset_mutex. All these locking changes
allow the hotplug code to call into cpuset core directly.

The following commits were also merged due to the asynchronous nature
of cpuset hotplug processing.

- commit b22afcdf04c9 ("cpu/hotplug: Cure the cpusets trainwreck")
- commit 50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume
bugs")
- commit 28b89b9e6f7b ("cpuset: handle race between CPU hotplug and
cpuset_hotplug_work")

Clean up all these bandages by making cpuset hotplug
processing synchronous again with the exception that the call to
cgroup_transfer_tasks() to transfer tasks out of an empty cgroup v1
cpuset, if necessary, will still be done via a work function due to the
existing cgroup_mutex -> cpu_hotplug_lock dependency. It is possible
to reverse that dependency, but that will require updating a number of
different cgroup controllers. This special hotplug code path should be
rarely taken anyway.

As all the cpuset states will be updated by the end of the hotplug
operation, we can revert most the above commits except commit
50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs")
which is partially reverted. Also removing some cpus_read_lock trylock
attempts in the cpuset partition code as they are no longer necessary
since the cpu_hotplug_lock is now held for the whole duration of the
cpuset hotplug code path.

Signed-off-by: Waiman Long <[email protected]>
Tested-by: Valentin Schneider <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

show more ...

workqueue: Introduce show_freezable_workqueues

Currently show_all_workqueue is called if freeze fails at the time of
freeze the workqueues, which shows the status of all workqueues and of
all worker

workqueue: Introduce show_freezable_workqueues

Currently show_all_workqueue is called if freeze fails at the time of
freeze the workqueues, which shows the status of all workqueues and of
all worker pools. In this cases we may only need to dump state of only
workqueues that are freezable and busy.

This patch defines show_freezable_workqueues, which uses
show_one_workqueue, a granular function that shows the state of individual
workqueues, so that dump only the state of freezable workqueues
at that time.

tj: Minor message adjustment.

Signed-off-by: Jungseung Lee <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

show more ...

PM: sleep: Refine error message in try_to_freeze_tasks()

A previous change amended try_to_freeze_tasks() with the "what"
variable pointing to a string describing the group of tasks subject to
the fr

PM: sleep: Refine error message in try_to_freeze_tasks()

A previous change amended try_to_freeze_tasks() with the "what"
variable pointing to a string describing the group of tasks subject to
the freezing which may be used in the error message in there too, so
make that happen.

Accordingly, update sleepgraph.py to catch the modified error message
as appropriate.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>

show more ...

PM: sleep: Avoid using pr_cont() in the tasks freezing code

Using pr_cont() in the tasks freezing code related to system-wide
suspend and hibernation is problematic, because the continuation
message

PM: sleep: Avoid using pr_cont() in the tasks freezing code

Using pr_cont() in the tasks freezing code related to system-wide
suspend and hibernation is problematic, because the continuation
messages printed there are susceptible to interspersing with other
unrelated messages which results in output that is hard to
understand.

Address this issue by modifying try_to_freeze_tasks() to print
messages that don't require continuations and adjusting its
callers accordingly.

Reported-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>

show more ...

freezer,sched: Rewrite core freezer logic

Rewrite the core freezer to behave better wrt thawing and be simpler
in general.

By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is
ensu

freezer,sched: Rewrite core freezer logic

Rewrite the core freezer to behave better wrt thawing and be simpler
in general.

By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is
ensured frozen tasks stay frozen until thawed and don't randomly wake
up early, as is currently possible.

As such, it does away with PF_FROZEN and PF_FREEZER_SKIP, freeing up
two PF_flags (yay!).

Specifically; the current scheme works a little like:

freezer_do_not_count();
schedule();
freezer_count();

And either the task is blocked, or it lands in try_to_freezer()
through freezer_count(). Now, when it is blocked, the freezer
considers it frozen and continues.

However, on thawing, once pm_freezing is cleared, freezer_count()
stops working, and any random/spurious wakeup will let a task run
before its time.

That is, thawing tries to thaw things in explicit order; kernel
threads and workqueues before doing bringing SMP back before userspace
etc.. However due to the above mentioned races it is entirely possible
for userspace tasks to thaw (by accident) before SMP is back.

This can be a fatal problem in asymmetric ISA architectures (eg ARMv9)
where the userspace task requires a special CPU to run.

As said; replace this with a special task state TASK_FROZEN and add
the following state transitions:

TASK_FREEZABLE -> TASK_FROZEN
__TASK_STOPPED -> TASK_FROZEN
__TASK_TRACED -> TASK_FROZEN

The new TASK_FREEZABLE can be set on any state part of TASK_NORMAL
(IOW. TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE) -- any such state
is already required to deal with spurious wakeups and the freezer
causes one such when thawing the task (since the original state is
lost).

The special __TASK_{STOPPED,TRACED} states *can* be restored since
their canonical state is in ->jobctl.

With this, frozen tasks need an explicit TASK_FROZEN wakeup and are
free of undue (early / spurious) wakeups.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Ingo Molnar <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

PM: sleep: Narrow down -DDEBUG on kernel/power/ files

The macro -DDEBUG is broadly enabled on kernel/power/ directory if
CONFIG_DYNAMIC_DEBUG is enabled. As side effect all debug messages using
pr_d

PM: sleep: Narrow down -DDEBUG on kernel/power/ files

The macro -DDEBUG is broadly enabled on kernel/power/ directory if
CONFIG_DYNAMIC_DEBUG is enabled. As side effect all debug messages using
pr_debug() and dev_dbg() are enabled by default on dynamic debug.
We're reworking pm_pr_dbg() to support dynamic debug, where pm_pr_dbg()
will print message if either pm_debug_messages_on flag is set or if it's
explicitly enabled on dynamic debug's control. That means if we let
-DDEBUG broadly set, the pm_debug_messages_on flag will be bypassed by
default on pm_pr_dbg() if dynamic debug is also enabled.

The files that directly use pr_debug() and dev_dbg() on kernel/power/ are:
- swap.c
- snapshot.c
- energy_model.c

And those files do not use pm_pr_dbg(). So if we limit -DDEBUG to them,
we keep the same functional behavior while allowing the pm_pr_dbg()
refactor.

Signed-off-by: David Cohen <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

PM: s2idle: ACPI: Fix wakeup interrupts handling

After commit e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race
related to the EC GPE") wakeup interrupts occurring immediately after
the one disca

PM: s2idle: ACPI: Fix wakeup interrupts handling

After commit e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race
related to the EC GPE") wakeup interrupts occurring immediately after
the one discarded by acpi_s2idle_wake() may be missed. Moreover, if
the SCI triggers again immediately after the rearming in
acpi_s2idle_wake(), that wakeup may be missed too.

The problem is that pm_system_irq_wakeup() only calls pm_system_wakeup()
when pm_wakeup_irq is 0, but that's not the case any more after the
interrupt causing acpi_s2idle_wake() to run until pm_wakeup_irq is
cleared by the pm_wakeup_clear() call in s2idle_loop(). However,
there may be wakeup interrupts occurring in that time frame and if
that happens, they will be missed.

To address that issue first move the clearing of pm_wakeup_irq to
the point at which it is known that the interrupt causing
acpi_s2idle_wake() to tun will be discarded, before rearming the SCI
for wakeup. Moreover, because that only reduces the size of the
time window in which the issue may manifest itself, allow
pm_system_irq_wakeup() to register two second wakeup interrupts in
a row and, when discarding the first one, replace it with the second
one. [Of course, this assumes that only one wakeup interrupt can be
discarded in one go, but currently that is the case and I am not
aware of any plans to change that.]

Fixes: e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race related to the EC GPE")
Cc: 5.4+ <[email protected]> # 5.4+
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

workqueue: Introduce show_one_worker_pool and show_one_workqueue.

Currently show_workqueue_state shows the state of all workqueues and of
all worker pools. In certain cases we may need to dump state

workqueue: Introduce show_one_worker_pool and show_one_workqueue.

Currently show_workqueue_state shows the state of all workqueues and of
all worker pools. In certain cases we may need to dump state of only a
specific workqueue or worker pool. For example in destroy_workqueue we
only need to show state of the workqueue which is getting destroyed.

So rename show_workqueue_state to show_all_workqueues(to signify it
dumps state of all busy workqueues) and divide it into more granular
functions (show_one_workqueue and show_one_worker_pool), that would show
states of individual workqueues and worker pools and can be used in
cases such as the one mentioned above.

Also, as mentioned earlier, make destroy_workqueue dump data pertaining
to only the workqueue that is being destroyed and make user(s) of
earlier interface(show_workqueue_state), use new interface
(show_all_workqueues).

Signed-off-by: Imran Khan <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

show more ...

PM: sleep: remove trailing spaces and tabs

Run the following command to find and remove the trailing spaces and tabs:

$ find kernel/power/ -type f | xargs sed -r -i 's/[ \t]+$//'

Signed-off-by: Zh

PM: sleep: remove trailing spaces and tabs

Run the following command to find and remove the trailing spaces and tabs:

$ find kernel/power/ -type f | xargs sed -r -i 's/[ \t]+$//'

Signed-off-by: Zhen Lei <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

PM: sleep: No need to check PF_WQ_WORKER in thaw_kernel_threads()

Because PF_KTHREAD is set for all wq worker threads, it is
not necessary to check PF_WQ_WORKER in addition to it in
thaw_kernel_thre

PM: sleep: No need to check PF_WQ_WORKER in thaw_kernel_threads()

Because PF_KTHREAD is set for all wq worker threads, it is
not necessary to check PF_WQ_WORKER in addition to it in
thaw_kernel_threads(), so stop doing that.

Signed-off-by: Zqiang <[email protected]>
[ rjw: Subject and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

PM: sleep: fix typo in kernel/power/process.c

Fix a typo in a comment in freeze_processes().

Signed-off-by: Jackie Zamow <[email protected]>
[ rjw: Subject and changelog edits ]
Signed-off-by:

PM: sleep: fix typo in kernel/power/process.c

Fix a typo in a comment in freeze_processes().

Signed-off-by: Jackie Zamow <[email protected]>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

Revert "cpuset: Make cpuset hotplug synchronous"

This reverts commit a49e4629b5ed ("cpuset: Make cpuset hotplug synchronous") as
it may deadlock with cpu hotplug path.

Link: http://lkml.kernel.org/

Revert "cpuset: Make cpuset hotplug synchronous"

This reverts commit a49e4629b5ed ("cpuset: Make cpuset hotplug synchronous") as
it may deadlock with cpu hotplug path.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Tejun Heo <[email protected]>
Reported-by: Qian Cai <[email protected]>
Cc: Prateek Sood <[email protected]>

show more ...

cpuset: Make cpuset hotplug synchronous

Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.

Since cpuset_hotplug

cpuset: Make cpuset hotplug synchronous

Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.

Since cpuset_hotplug_workfn() can be made synchronous for cpu hotplug
path, it is not required to wait for cpuset hotplug while thawing
processes.

Signed-off-by: Prateek Sood <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

show more ...

PM / sleep: Show freezing tasks that caused a suspend abort

For debug purposes it would be nice to see which tasks
caused a suspend abort, i.e. which tasks were still
in the process of freezing when

PM / sleep: Show freezing tasks that caused a suspend abort

For debug purposes it would be nice to see which tasks
caused a suspend abort, i.e. which tasks were still
in the process of freezing when a wakeup event occurred.
This patch adds the info to pm_debug_messages.

Signed-off-by: Todd Brandt <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

Revert "cpuset: Make cpuset hotplug synchronous"

This reverts commit 1599a185f0e6113be185b9fb809c621c73865829.

This and the previous commit led to another circular locking scenario
and the scenario

Revert "cpuset: Make cpuset hotplug synchronous"

This reverts commit 1599a185f0e6113be185b9fb809c621c73865829.

This and the previous commit led to another circular locking scenario
and the scenario which is fixed by this commit no longer exists after
e8b3f8db7aad ("workqueue/hotplug: simplify workqueue_offline_cpu()")
which removes work item flushing from hotplug path.

Revert it for now.

Signed-off-by: Tejun Heo <[email protected]>

show more ...

cpuset: Make cpuset hotplug synchronous

Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.

Since cpuset_hotplug

cpuset: Make cpuset hotplug synchronous

Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.

Since cpuset_hotplug_workfn() can be made synchronous for cpu hotplug
path, it is not required to wait for cpuset hotplug while thawing
processes.

Signed-off-by: Prateek Sood <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

show more ...

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs

Cpusets vs. suspend-resume is _completely_ broken. And it got noticed
because it now resulted in non-cpuset usage breaking too.

On suspend cpuset

sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs

Cpusets vs. suspend-resume is _completely_ broken. And it got noticed
because it now resulted in non-cpuset usage breaking too.

On suspend cpuset_cpu_inactive() doesn't call into
cpuset_update_active_cpus() because it doesn't want to move tasks about,
there is no need, all tasks are frozen and won't run again until after
we've resumed everything.

But this means that when we finally do call into
cpuset_update_active_cpus() after resuming the last frozen cpu in
cpuset_cpu_active(), the top_cpuset will not have any difference with
the cpu_active_mask and this it will not in fact do _anything_.

So the cpuset configuration will not be restored. This was largely
hidden because we would unconditionally create identity domains and
mobile users would not in fact use cpusets much. And servers what do use
cpusets tend to not suspend-resume much.

An addition problem is that we'd not in fact wait for the cpuset work to
finish before resuming the tasks, allowing spurious migrations outside
of the specified domains.

Fix the rebuild by introducing cpuset_force_rebuild() and fix the
ordering with cpuset_wait_for_hotplug().

Reported-by: Andy Lutomirski <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: deb7aa308ea2 ("cpuset: reorganize CPU / memory hotplug handling")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
signale

ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
signaled through it wake up the system from that state. However,
on some systems some of the events signaled via the ACPI SCI while
suspended to idle should not cause the system to wake up. In fact,
quite often they should just be discarded.

Arguably, systems should not resume entirely on such events, but in
order to decide which events really should cause the system to resume
and which are spurious, it is necessary to resume up to the point
when ACPI SCIs are actually handled and processed, which is after
executing dpm_resume_noirq() in the system resume path.

For this reasons, add a loop around freeze_enter() in which the
platforms can process events signaled via multiplexed IRQ lines
like the ACPI SCI and add suspend-to-idle hooks that can be
used for this purpose to struct platform_freeze_ops.

In the ACPI case, the ->wake hook is used for checking if the SCI
has triggered while suspended and deferring the interrupt-induced
system wakeup until the events signaled through it are actually
processed sufficiently to decide whether or not the system should
resume. In turn, the ->sync hook allows all of the relevant event
queues to be flushed so as to prevent events from being missed due
to race conditions.

In addition to that, some ACPI code processing wakeup events needs
to be modified to use the "hard" version of wakeup triggers, so that
it will cause a system resume to happen on device-induced wakeup
events even if the "soft" mechanism to prevent the system from
suspending is not enabled. However, to preserve the existing
behavior with respect to suspend-to-RAM, this only is done in
the suspend-to-idle case and only if an SCI has occurred while
suspended.

Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

Revert "ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle"

Revert commit eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups
from suspend-to-idle) as it turned out to be premature a

Revert "ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle"

Revert commit eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups
from suspend-to-idle) as it turned out to be premature and triggered
a number of different issues on various systems.

That includes, but is not limited to, premature suspend-to-RAM aborts
on Dell XPS 13 (9343) reported by Dominik.

The issue the commit in question attempted to address is real and
will need to be taken care of going forward, but evidently more work
is needed for this purpose.

Reported-by: Dominik Brodowski <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
sign

ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
signaled through it wake up the system from that state. However,
on some systems some of the events signaled via the ACPI SCI while
suspended to idle should not cause the system to wake up. In fact,
quite often they should just be discarded.

Arguably, systems should not resume entirely on such events, but in
order to decide which events really should cause the system to resume
and which are spurious, it is necessary to resume up to the point
when ACPI SCIs are actually handled and processed, which is after
executing dpm_resume_noirq() in the system resume path.

For this reasons, add a loop around freeze_enter() in which the
platforms can process events signaled via multiplexed IRQ lines
like the ACPI SCI and add suspend-to-idle hooks that can be
used for this purpose to struct platform_freeze_ops.

In the ACPI case, the ->wake hook is used for checking if the SCI
has triggered while suspended and deferring the interrupt-induced
system wakeup until the events signaled through it are actually
processed sufficiently to decide whether or not the system should
resume. In turn, the ->sync hook allows all of the relevant event
queues to be flushed so as to prevent events from being missed due
to race conditions.

In addition to that, some ACPI code processing wakeup events needs
to be modified to use the "hard" version of wakeup triggers, so that
it will cause a system resume to happen on device-induced wakeup
events even if the "soft" mechanism to prevent the system from
suspending is not enabled (that also helps to catch device-induced
wakeup events occurring during suspend transitions in progress).

Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>

We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>

We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up fro

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

oom, suspend: fix oom_killer_disable vs. pm suspend properly

Commit 74070542099c ("oom, suspend: fix oom_reaper vs.
oom_killer_disable race") has workaround an existing race between
oom_killer_disab

oom, suspend: fix oom_killer_disable vs. pm suspend properly

Commit 74070542099c ("oom, suspend: fix oom_reaper vs.
oom_killer_disable race") has workaround an existing race between
oom_killer_disable and oom_reaper by adding another round of
try_to_freeze_tasks after the oom killer was disabled. This was the
easiest thing to do for a late 4.7 fix. Let's fix it properly now.

After "oom: keep mm of the killed task available" we no longer have to
call exit_oom_victim from the oom reaper because we have stable mm
available and hide the oom_reaped mm by MMF_OOM_SKIP flag. So let's
remove exit_oom_victim and the race described in the above commit
doesn't exist anymore if.

Unfortunately this alone is not sufficient for the oom_killer_disable
usecase because now we do not have any reliable way to reach
exit_oom_victim (the victim might get stuck on a way to exit for an
unbounded amount of time). OOM killer can cope with that by checking mm
flags and move on to another victim but we cannot do the same for
oom_killer_disable as we would lose the guarantee of no further
interference of the victim with the rest of the system. What we can do
instead is to cap the maximum time the oom_killer_disable waits for
victims. The only current user of this function (pm suspend) already
has a concept of timeout for back off so we can reuse the same value
there.

Let's drop set_freezable for the oom_reaper kthread because it is no
longer needed as the reaper doesn't wake or thaw any processes.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

PM / suspend: show workqueue state in suspend flow

If freezable workqueue aborts suspend flow, show
workqueue state for debug purpose.

Signed-off-by: Roger Lu <[email protected]>
Acked-by: Teju

PM / suspend: show workqueue state in suspend flow

If freezable workqueue aborts suspend flow, show
workqueue state for debug purpose.

Signed-off-by: Roger Lu <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...