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Andy Lutomirski 675357362a Revert "x86/mm: Stop calling leave_mm() in idle code" This reverts commit `43858b4f25`. The reason I removed the leave_mm() calls in question is because the heuristic wasn't needed after that patch. With the original version of my PCID series, we never flushed a "lazy cpu" (i.e. a CPU running kernel thread) due a flush on the loaded mm. Unfortunately, that caused architectural issues, so now I've reinstated these flushes on non-PCID systems in: commit `b956575bed` ("x86/mm: Flush more aggressively in lazy TLB mode"). That, in turn, gives us a power management and occasionally performance regression as compared to old kernels: a process that goes into a deep idle state on a given CPU and gets its mm flushed due to activity on a different CPU will wake the idle CPU. Reinstate the old ugly heuristic: if a CPU goes into ACPI C3 or an intel_idle state that is likely to cause a TLB flush gets its mm switched to init_mm before going idle. FWIW, this heuristic is lousy. Whether we should change CR3 before idle isn't a good hint except insofar as the performance hit is a bit lower if the TLB is getting flushed by the idle code anyway. What we really want to know is whether we anticipate being idle long enough that the mm is likely to be flushed before we wake up. This is more a matter of the expected latency than the idle state that gets chosen. This heuristic also completely fails on systems that don't know whether the TLB will be flushed (e.g. AMD systems?). OTOH it may be a bit obsolete anyway -- PCID systems don't presently benefit from this heuristic at all. We also shouldn't do this callback from innermost bit of the idle code due to the RCU nastiness it causes. All the information need is available before rcu_idle_enter() needs to happen. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: `43858b4f25` "x86/mm: Stop calling leave_mm() in idle code" Link: http://lkml.kernel.org/r/c513bbd4e653747213e05bc7062de000bf0202a5.1509793738.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>		2017-11-04 15:01:50 +01:00
arch	Revert "x86/mm: Stop calling leave_mm() in idle code"	2017-11-04 15:01:50 +01:00
block	bio_copy_user_iov(): don't ignore ->iov_offset	2017-10-10 23:55:14 -04:00
certs	modsign: add markers to endif-statements in certs/Makefile	2017-07-14 11:01:37 +10:00
crypto	Merge commit 'tags/keys-fixes-20171018' into fixes-v4.14-rc5	2017-10-19 12:28:38 +11:00
Documentation	Kbuild fixes for v4.14 (2nd)	2017-10-28 11:01:57 -07:00
drivers	Revert "x86/mm: Stop calling leave_mm() in idle code"	2017-11-04 15:01:50 +01:00
firmware	firmware: Restore support for built-in firmware	2017-09-16 10:58:48 -07:00
fs	Various SMB3 fixes for 4.14 and stable	2017-10-28 08:39:35 -07:00
include	PM / QoS: Fix default runtime_pm device resume latency	2017-10-30 10:54:57 +01:00
init	kbuild: Fix optimization level choice default	2017-10-07 20:08:05 +09:00
ipc	fix a typo in put_compat_shm_info()	2017-09-25 20:41:46 -04:00
kernel	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-10-29 08:11:49 -07:00
lib	Mark 'ioremap_page_range()' as possibly sleeping	2017-10-30 10:09:56 -07:00
mm	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-10-21 22:44:48 -04:00
net	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-10-29 08:11:49 -07:00
samples	Fix tracing sample code warning.	2017-10-27 20:35:31 -07:00
scripts	Kbuild fixes for v4.14 (2nd)	2017-10-28 11:01:57 -07:00
security	Revert "apparmor: add base infastructure for socket mediation"	2017-10-26 19:35:35 +02:00
sound	ALSA: hda - fix headset mic problem for Dell machines with alc236	2017-10-24 14:32:24 +02:00
tools	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-10-29 08:11:49 -07:00
usr	ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk.	2017-07-06 16:24:30 -07:00
virt	Revert "KVM: Don't accept obviously wrong gsi values via KVM_IRQFD"	2017-09-19 08:37:17 +02:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	Add hch to .get_maintainer.ignore	2015-08-21 14:30:10 -07:00
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	kbuild: Add support to generate LLVM assembly files	2017-04-25 08:13:52 +09:00
.mailmap	Update James Hogan's email address	2017-10-04 17:11:53 -07:00
COPYING
CREDITS	selinux/stable-4.14 PR 20170831	2017-09-12 13:21:00 -07:00
Kbuild	kbuild: Consolidate header generation from ASM offset information	2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS	xen: fixes for 4.14-rc7	2017-10-27 20:41:05 -07:00
Makefile	Linux 4.14-rc7	2017-10-29 13:58:38 -07:00
README	README: add a new README file, pointing to the Documentation/	2016-10-24 08:12:35 -02:00

README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.