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Linux kernel for uConsole
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Vincent Guittot 2d935df7b2 sched/fair: Fix insertion in rq->leaf_cfs_rq_list 
commit f678331973 upstream.

Sargun reported a crash:

  "I picked up c40f7d74c7 sched/fair: Fix
   infinite loop in update_blocked_averages() by reverting a9e7f6544b
   and put it on top of 4.19.13. In addition to this, I uninlined
   list_add_leaf_cfs_rq for debugging.

   This revealed a new bug that we didn't get to because we kept getting
   crashes from the previous issue. When we are running with cgroups that
   are rapidly changing, with CFS bandwidth control, and in addition
   using the cpusets cgroup, we see this crash. Specifically, it seems to
   occur with cgroups that are throttled and we change the allowed
   cpuset."

The algorithm used to order cfs_rq in rq->leaf_cfs_rq_list assumes that
it will walk down to root the 1st time a cfs_rq is used and we will finish
to add either a cfs_rq without parent or a cfs_rq with a parent that is
already on the list. But this is not always true in presence of throttling.
Because a cfs_rq can be throttled even if it has never been used but other CPUs
of the cgroup have already used all the bandwdith, we are not sure to go down to
the root and add all cfs_rq in the list.

Ensure that all cfs_rq will be added in the list even if they are throttled.

[ mingo: Fix !CGROUPS build. ]

Reported-by: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: tj@kernel.org
Fixes: 9c2791f936 ("Fix hierarchical order in rq->leaf_cfs_rq_list")
Link: https://lkml.kernel.org/r/1548825767-10799-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Janne Huttunen <janne.huttunen@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-01 09:37:10 +00:00
arch arc: eznps: fix allmodconfig kconfig warning 2020-02-01 09:37:06 +00:00
block block: don't use bio->bi_vcnt to figure out segment number 2020-01-27 14:50:23 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: tgr192 - fix unaligned memory access 2020-01-27 14:50:13 +01:00
Documentation Documentation: Document arm64 kpti control 2020-01-29 16:43:19 +01:00
drivers usb-storage: Disable UAS on JMicron SATA enclosure 2020-02-01 09:37:10 +00:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:21:29 +01:00
fs cifs: Fix memory allocation in __smb2_handle_cancelled_cmd() 2020-02-01 09:37:04 +00:00
include ARM: OMAP2+: SmartReflex: add omap_sr_pdata definition 2020-02-01 09:37:10 +00:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel sched/fair: Fix insertion in rq->leaf_cfs_rq_list 2020-02-01 09:37:10 +00:00
lib Partially revert "kfifo: fix kfifo_alloc() and kfifo_init()" 2020-01-27 14:51:08 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory_hotplug: shrink zones when offlining memory 2020-01-29 16:43:27 +01:00
net net_sched: fix ops->bind_class() implementations 2020-02-01 09:37:06 +00:00
samples samples/bpf: Fix broken xdp_rxq_info due to map order assumptions 2020-01-27 14:51:22 +01:00
scripts ARM: 8950/1: ftrace/recordmcount: filter relocation types 2020-01-29 16:43:19 +01:00
security keys: Timestamp new keys 2020-01-27 14:50:23 +01:00
sound ASoC: sun4i-i2s: RX and TX counter registers are swapped 2020-01-27 14:51:05 +01:00
tools tools: bpftool: fix format strings and arguments for jsonw_printf() 2020-01-27 14:51:05 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt KVM: arm/arm64: vgic: Don't rely on the wrong pending table 2019-12-13 08:52:45 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.100 2020-01-29 16:43:27 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.