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Linus Torvalds 5256184b61 Fixes and minor updates for the timer migration code:
- Stop testing the group->parent pointer as it is not guaranteed to be
       stable over a chain of operations by design. This includes a warning
       which would be nice to have but it produces false positives due to
       the racy nature of the check.
 
     - Plug a race between CPUs going in and out of idle and a CPU hotplug
       operation. The latter can create and connect a new hierarchy level
       which is missed in the concurrent updates of CPUs which go into idle.
       As a result the events of such a CPU might not be processed and
       timers go stale.
 
       Cure it by splitting the hotplug operation into a prepare and online
       callback. The prepare callback is guaranteed to run on an online and
       therefore active CPU. This CPU updates the hierarchy and being online
       ensures that there is always at least one migrator active which
       handles the modified hierarchy correctly when going idle. The online
       callback which runs on the incoming CPU then just marks the CPU
       active and brings it into operation.
 
     - Improve tracing and polish the code further so it is more obvious
       what's going on.
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Merge tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer migration updates from Thomas Gleixner:
 "Fixes and minor updates for the timer migration code:

   - Stop testing the group->parent pointer as it is not guaranteed to
     be stable over a chain of operations by design.

     This includes a warning which would be nice to have but it produces
     false positives due to the racy nature of the check.

   - Plug a race between CPUs going in and out of idle and a CPU hotplug
     operation. The latter can create and connect a new hierarchy level
     which is missed in the concurrent updates of CPUs which go into
     idle. As a result the events of such a CPU might not be processed
     and timers go stale.

     Cure it by splitting the hotplug operation into a prepare and
     online callback. The prepare callback is guaranteed to run on an
     online and therefore active CPU. This CPU updates the hierarchy and
     being online ensures that there is always at least one migrator
     active which handles the modified hierarchy correctly when going
     idle. The online callback which runs on the incoming CPU then just
     marks the CPU active and brings it into operation.

   - Improve tracing and polish the code further so it is more obvious
     what's going on"

* tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers/migration: Fix grammar in comment
  timers/migration: Spare write when nothing changed
  timers/migration: Rename childmask by groupmask to make naming more obvious
  timers/migration: Read childmask and parent pointer in a single place
  timers/migration: Use a single struct for hierarchy walk data
  timers/migration: Improve tracing
  timers/migration: Move hierarchy setup into cpuhotplug prepare callback
  timers/migration: Do not rely always on group->parent
2024-07-27 10:19:55 -07:00
arch RISC-V Patches for the 6.11 Merge Window, Part 2 2024-07-27 10:14:34 -07:00
block for-6.11/block-20240722 2024-07-22 11:32:05 -07:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation RISC-V Patches for the 6.11 Merge Window, Part 2 2024-07-27 10:14:34 -07:00
drivers RISC-V Patches for the 6.11 Merge Window, Part 2 2024-07-27 10:14:34 -07:00
fs A small patchset to address bogus I/O errors and ultimately an 2024-07-26 10:34:42 -07:00
include Fixes and minor updates for the timer migration code: 2024-07-27 10:19:55 -07:00
init Kbuild updates for v6.11 2024-07-23 14:32:21 -07:00
io_uring io_uring: fix error pbuf checking 2024-07-20 11:04:57 -06:00
ipc sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kernel Fixes and minor updates for the timer migration code: 2024-07-27 10:19:55 -07:00
lib bitmap-6.11-rc1 2024-07-26 09:50:36 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
net A lot of networking people were at a conference last week, busy 2024-07-25 13:32:25 -07:00
rust This pull request contains the following changes for UML: 2024-07-25 12:33:08 -07:00
samples Driver core changes for 6.11-rc1 2024-07-25 10:42:22 -07:00
scripts This pull request contains the following changes for UML: 2024-07-25 12:33:08 -07:00
security sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
sound sound fixes for 6.11-rc1 2024-07-26 11:01:31 -07:00
tools arm64 fixes for -rc1 2024-07-26 10:39:10 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM generic changes for 6.11 2024-07-16 09:51:36 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: add script and target to generate pacman package 2024-07-22 01:24:22 +09:00
.mailmap MAINTAINERS: Update email address of Naveen 2024-07-17 19:27:18 +02:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
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 A lot of networking people were at a conference last week, busy 2024-07-25 13:32:25 -07:00
Makefile Kbuild updates for v6.11 2024-07-23 14:32:21 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 reStructuredText 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.