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Linus Torvalds 4ba1329cbb Urgent RCU pull request for v5.19
This pull request contains a pair of commits that fix 282d8998e9 ("srcu:
 Prevent expedited GPs and blocking readers from consuming CPU"), which
 was itself a fix to an SRCU expedited grace-period problem that could
 prevent kernel live patching (KLP) from completing.  That SRCU fix for
 KLP introduced large (as in minutes) boot-time delays to embedded Linux
 kernels running on qemu/KVM.  These delays were due to the emulation of
 certain MMIO operations controlling memory layout, which were emulated
 with one expedited grace period per access.  Common configurations
 required thousands of boot-time MMIO accesses, and thus thousands of
 boot-time expedited SRCU grace periods.
 
 In these configurations, the occasional sleeps that allowed KLP to proceed
 caused excessive boot delays.  These commits preserve enough sleeps to
 permit KLP to proceed, but few enough that the virtual embedded kernels
 still boot reasonably quickly.
 
 This represents a regression introduced in the v5.19 merge window,
 and the bug is causing significant inconvenience, hence this pull request.
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Merge tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU fix from Paul McKenney:
 "This contains a pair of commits that fix 282d8998e9 ("srcu: Prevent
  expedited GPs and blocking readers from consuming CPU"), which was
  itself a fix to an SRCU expedited grace-period problem that could
  prevent kernel live patching (KLP) from completing.

  That SRCU fix for KLP introduced large (as in minutes) boot-time
  delays to embedded Linux kernels running on qemu/KVM. These delays
  were due to the emulation of certain MMIO operations controlling
  memory layout, which were emulated with one expedited grace period per
  access. Common configurations required thousands of boot-time MMIO
  accesses, and thus thousands of boot-time expedited SRCU grace
  periods.

  In these configurations, the occasional sleeps that allowed KLP to
  proceed caused excessive boot delays. These commits preserve enough
  sleeps to permit KLP to proceed, but few enough that the virtual
  embedded kernels still boot reasonably quickly.

  This represents a regression introduced in the v5.19 merge window, and
  the bug is causing significant inconvenience"

* tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  srcu: Make expedited RCU grace periods block even less frequently
  srcu: Block less aggressively for expedited grace periods
2022-07-22 10:01:20 -07:00
arch csky/tlb: Remove tlb_flush() define 2022-07-21 10:50:13 -07:00
block block: fix missing blkcg_bio_issue_init 2022-07-14 10:54:49 -06:00
certs Certs changes 2022-06-21 12:13:53 -05:00
crypto crypto: s390 - do not depend on CRYPTO_HW for SIMD implementations 2022-07-06 20:04:06 -07:00
Documentation Urgent RCU pull request for v5.19 2022-07-22 10:01:20 -07:00
drivers NAND controller fix: 2022-07-21 11:28:26 -07:00
fs for-5.19-rc7-tag 2022-07-16 13:48:55 -07:00
include mmu_gather: fix the CONFIG_MMU_GATHER_NO_RANGE case 2022-07-22 09:28:34 -07:00
init gcc-12: disable '-Warray-bounds' universally for now 2022-06-09 10:11:12 -07:00
ipc ipc: Free mq_sysctls if ipc namespace creation failed 2022-06-22 17:47:41 -05:00
kernel Urgent RCU pull request for v5.19 2022-07-22 10:01:20 -07:00
lib ubsan: disable UBSAN_DIV_ZERO for clang 2022-07-14 15:45:26 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: split huge PUD on wp_huge_pud fallback 2022-07-03 15:42:33 -07:00
net net/sched: cls_api: Fix flow action initialization 2022-07-20 10:54:27 +01:00
samples Fixes and minor clean ups for tracing: 2022-07-12 16:17:40 -07:00
scripts scripts/gdb: Fix gdb 'lx-symbols' command 2022-07-21 10:40:55 -07:00
security lockdown: Fix kexec lockdown bypass with ima policy 2022-07-20 09:56:48 -07:00
sound ALSA: hda/realtek - Enable the headset-mic on a Xiaomi's laptop 2022-07-13 12:42:41 +02:00
tools perf trace: Fix SIGSEGV when processing syscall args 2022-07-17 10:59:52 -03:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 2022-06-09 10:52:20 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap cxl fixes for 5.19-rc6 2022-07-08 12:55:25 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan 2022-07-07 15:17:00 +02:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS spi: Fixes for v5.19 2022-07-15 10:23:43 -07:00
Makefile Linux 5.19-rc7 2022-07-17 13:30:22 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 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.