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Sebastian Andrzej Siewior 28557cc106 Revert mm/vmstat.c: fix vmstat_update() preemption BUG 
Revert commit c7f26ccfb2 ("mm/vmstat.c: fix vmstat_update() preemption
BUG").  Steven saw a "using smp_processor_id() in preemptible" message
and added a preempt_disable() section around it to keep it quiet.  This
is not the right thing to do it does not fix the real problem.

vmstat_update() is invoked by a kworker on a specific CPU.  This worker
it bound to this CPU.  The name of the worker was "kworker/1:1" so it
should have been a worker which was bound to CPU1.  A worker which can
run on any CPU would have a `u' before the first digit.

smp_processor_id() can be used in a preempt-enabled region as long as
the task is bound to a single CPU which is the case here.  If it could
run on an arbitrary CPU then this is the problem we have an should seek
to resolve.

Not only this smp_processor_id() must not be migrated to another CPU but
also refresh_cpu_vm_stats() which might access wrong per-CPU variables.
Not to mention that other code relies on the fact that such a worker
runs on one specific CPU only.

Therefore revert that commit and we should look instead what broke the
affinity mask of the kworker.

Link: http://lkml.kernel.org/r/20180504104451.20278-1-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven J. Hill <steven.hill@cavium.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-28 11:16:44 -07:00
arch A single build fix for 4.18: 2018-06-27 09:56:23 -07:00
block for-linus-20180623 2018-06-24 06:33:54 +08:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Merge branch 'fixes-v4.18-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-06-26 08:44:15 -07:00
Documentation Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2018-06-27 09:16:53 -07:00
drivers ARM: SoC fixes for 4.18-rc 2018-06-27 09:53:53 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Changes since last update: 2018-06-27 12:21:06 -07:00
include SCSI fixes on 20180627 2018-06-27 09:42:16 -07:00
init dma-mapping: move all DMA mapping code to kernel/dma 2018-06-14 08:50:37 +02:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-24 20:29:15 +08:00
lib lib/percpu_ida.c: don't do alloc from per-CPU list if there is none 2018-06-28 11:16:44 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm Revert mm/vmstat.c: fix vmstat_update() preemption BUG 2018-06-28 11:16:44 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-25 15:58:17 +08:00
samples VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
scripts checkpatch: remove warning for 'old' stable@kernel.org address 2018-06-27 08:40:44 -07:00
security dh key: fix rounding up KDF output length 2018-06-26 09:43:05 -07:00
sound docs: Fix some broken references 2018-06-15 18:10:01 -03:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-25 15:58:17 +08:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM: arm64: Prevent KVM_COMPAT from being selected 2018-06-21 17:17:50 +01:00
.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 MAINTAINERS: Timur has a kernel.org address 2018-06-27 12:20:27 -07:00
Makefile Linux 4.18-rc2 2018-06-24 20:54:29 +08:00
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.