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Sebastian Andrzej Siewior af0fffd930 sched/core: Remove get_cpu() from sched_fork() 
get_cpu() disables preemption for the entire sched_fork() function.
This get_cpu() was introduced in commit:

  dd41f596cd ("sched: cfs core code")

... which also invoked sched_balance_self() and this function
required preemption do be off.

Today, sched_balance_self() seems to be moved to ->task_fork callback
which is invoked while the ->pi_lock is held.

set_load_weight() could invoke reweight_task() which then via $callchain
might end up in smp_processor_id() but since `update_load' is false
this won't happen.

I didn't find any this_cpu*() or similar usage during the initialisation
of the task_struct.

The `cpu' value (from get_cpu()) is only used later in __set_task_cpu()
while the ->pi_lock lock is held.

Based on this it is possible to remove get_cpu() and use
smp_processor_id() for the `cpu' variable without breaking anything.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180706130615.g2ex2kmfu5kcvlq6@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 00:16:29 +02:00
arch Linux 4.18-rc5 2018-07-15 23:33:26 +02:00
block for-linus-20180713 2018-07-14 12:28:00 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
Documentation Kbuild fixes for v4.18 (2nd) 2018-07-13 12:15:12 -07:00
drivers RTC fixes for 4.18 2018-07-14 16:15:19 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs reiserfs: fix buffer overflow with long warning messages 2018-07-14 11:11:10 -07:00
include sched/sysctl: Remove unused sched_time_avg_ms sysctl 2018-07-16 00:16:29 +02:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel sched/core: Remove get_cpu() from sched_fork() 2018-07-16 00:16:29 +02:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-02 11:18:28 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm Merge branch 'akpm' (patches from Andrew) 2018-07-14 11:14:33 -07:00
net net/9p/client.c: put refcount of trans_mod in error case in parse_opts() 2018-07-14 11:11:09 -07:00
samples sample: vfio-mdev: avoid deadlock in mdev_access() 2018-07-11 13:22:41 -06:00
scripts checkpatch: fix duplicate invalid vsprintf pointer extension '%p<foo>' messages 2018-07-14 11:11:10 -07:00
security selinux/stable-4.18 PR 20180629 2018-06-30 11:15:12 -07:00
sound ALSA: hda/ca0132: Update a pci quirk device name 2018-07-12 09:18:31 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-13 13:33:09 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Merge branch 'sched/urgent' into sched/core, to pick up fixes 2018-07-03 09:20:22 +02:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.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 Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Char/Misc fixes for 4.18-rc5 2018-07-11 10:10:50 -07:00
Makefile Linux 4.18-rc5 2018-07-15 12:49:31 -07:00
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.