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Anna-Maria Behnsen 9fdfeef4c5 PM: s2idle: Make sure CPUs will wakeup directly on resume 
commit 3c89a068bf upstream.

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 (7ee9887703 ("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 8d89835b04 ("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: 8d89835b04 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-17 11:19:26 +02:00
arch ARM: dts: imx7s-warp: Pass OV2680 link-frequencies 2024-04-17 11:19:25 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 13:07:37 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: jitter - fix CRYPTO_JITTERENTROPY help text 2024-03-26 18:19:52 -04:00
Documentation x86/bhi: Mitigate KVM by default 2024-04-10 16:36:08 +02:00
drivers ACPI: scan: Do not increase dep_unmet for already met dependencies 2024-04-17 11:19:26 +02:00
fs smb3: fix Open files on server counter going negative 2024-04-17 11:19:24 +02:00
include net: mpls: error out if inner headers are not set 2024-04-13 13:07:41 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-03 15:28:53 +02:00
io_uring io_uring: clear opcode specific data for an early failure 2024-04-13 13:07:39 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel PM: s2idle: Make sure CPUs will wakeup directly on resume 2024-04-17 11:19:26 +02:00
lib pci_iounmap(): Fix MMIO mapping leak 2024-04-03 15:28:17 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-10 16:36:03 +02:00
net Bluetooth: Fix memory leak in hci_req_sync_complete() 2024-04-17 11:19:25 +02:00
rust rust: upgrade to Rust 1.73.0 2024-02-16 19:10:43 +01:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts gcc-plugins/stackleak: Avoid .head.text section 2024-04-13 13:07:40 +02:00
security selinux: avoid dereference of garbage after mount failure 2024-04-10 16:35:48 +02:00
sound ALSA: hda/realtek: Add quirks for some Clevo laptops 2024-04-13 13:07:40 +02:00
tools selftests: mptcp: display simult in extra_msg 2024-04-13 13:07:40 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:28:18 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Catherine as xfs maintainer for 6.6.y 2024-02-16 19:10:43 +01:00
Makefile Linux 6.6.27 2024-04-13 13:07:41 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.