linux-toradex.git/kernel/sysctl.c, branch v5.6-rc6

s390: remove obsolete ieee_emulation_warnings

2020-02-19T12:51:46+00:00

s390 math emulation was removed with commit 5a79859ae0f3 ("s390:
remove 31 bit support"), rendering ieee_emulation_warnings useless.
The code still built because it was protected by CONFIG_MATHEMU, which
was no longer selectable.

This patch removes the sysctl_ieee_emulation_warnings declaration and
the sysctl entry declaration.

Link: https://lkml.kernel.org/r/20200214172628.3598516-1-steve@sk2.org
Reviewed-by: Vasily Gorbik 
Signed-off-by: Stephen Kitt 
Signed-off-by: Vasily Gorbik

rcu: Make PREEMPT_RCU be a modifier to TREE_RCU

2019-12-09T20:37:51+00:00

Currently PREEMPT_RCU and TREE_RCU are mutually exclusive Kconfig
options.  But PREEMPT_RCU actually specifies a kind of TREE_RCU,
namely a preemptible TREE_RCU. This commit therefore makes PREEMPT_RCU
be a modifer to the TREE_RCU Kconfig option.  This has the benefit of
simplifying several of the #if expressions that formerly needed to
check both, but now need only check one or the other.

Signed-off-by: Lai Jiangshan 
Signed-off-by: Lai Jiangshan 
Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

kernel: sysctl: make drop_caches write-only

2019-12-01T20:59:07+00:00

Currently, the drop_caches proc file and sysctl read back the last value
written, suggesting this is somehow a stateful setting instead of a
one-time command.  Make it write-only, like e.g.  compact_memory.

While mitigating a VM problem at scale in our fleet, there was confusion
about whether writing to this file will permanently switch the kernel into
a non-caching mode.  This influences the decision making in a tense
situation, where tens of people are trying to fix tens of thousands of
affected machines: Do we need a rollback strategy?  What are the
performance implications of operating in a non-caching state for several
days?  It also caused confusion when the kernel team said we may need to
write the file several times to make sure it's effective ("But it already
reads back 3?").

Link: http://lkml.kernel.org/r/20191031221602.9375-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner 
Acked-by: Chris Down 
Acked-by: Vlastimil Babka 
Acked-by: David Hildenbrand 
Acked-by: Michal Hocko 
Acked-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

parisc: sysctl.c: Use CONFIG_PARISC instead of __hppa_ define

2019-10-14T19:43:54+00:00

Signed-off-by: Helge Deller

arm64, mm: move generic mmap layout functions to mm

2019-09-24T22:54:11+00:00

arm64 handles top-down mmap layout in a way that can be easily reused by
other architectures, so make it available in mm.  It then introduces a new
config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT that can be set by other
architectures to benefit from those functions.  Note that this new config
depends on MMU being enabled, if selected without MMU support, a warning
will be thrown.

Link: http://lkml.kernel.org/r/20190730055113.23635-5-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti 
Suggested-by: Christoph Hellwig 
Acked-by: Catalin Marinas 
Acked-by: Kees Cook 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Luis Chamberlain 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: James Hogan 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Russell King 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/sysctl: add shared variables for range check

2019-07-19T00:08:07+00:00

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range.  This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

    $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
    248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

    # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
    add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
    Data                                         old     new   delta
    sysctl_vals                                    -      12     +12
    __kstrtab_sysctl_vals                          -      12     +12
    max                                           14      10      -4
    int_max                                       16       -     -16
    one                                           68       -     -68
    zero                                         128      28    -100
    Total: Before=20583249, After=20583085, chg -0.00%

[mcroce@redhat.com: tipc: remove two unused variables]
  Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
  Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com
Signed-off-by: Matteo Croce 
Signed-off-by: Arnd Bergmann 
Acked-by: Kees Cook 
Reviewed-by: Aaron Tomlin 
Cc: Matthew Wilcox 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel: fix typos and some coding style in comments

2019-07-17T02:23:21+00:00

fix lenght to length

Link: http://lkml.kernel.org/r/20190521050937.4370-1-houweitaoo@gmail.com
Signed-off-by: Weitao Hou 
Acked-by: Kees Cook 
Cc: Colin Ian King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched/uclamp: Add system default clamps

2019-06-24T17:23:45+00:00

Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range.

Tasks with a user-defined clamp value are allowed to request any value
in that range, and the required clamp is unconditionally enforced.
However, a "System Management Software" could be interested in limiting
the range of clamp values allowed for all tasks.

Add a privileged interface to define a system default configuration via:

  /proc/sys/kernel/sched_uclamp_util_{min,max}

which works as an unconditional clamp range restriction for all tasks.

With the default configuration, the full SCHED_CAPACITY_SCALE range of
values is allowed for each clamp index. Otherwise, the task-specific
clamp is capped by the corresponding system default value.

Do that by tracking, for each task, the "effective" clamp value and
bucket the task has been refcounted in at enqueue time. This
allows to lazy aggregate "requested" and "system default" values at
enqueue time and simplifies refcounting updates at dequeue time.

The cached bucket ids are used to avoid (relatively) more expensive
integer divisions every time a task is enqueued.

An active flag is used to report when the "effective" value is valid and
thus the task is actually refcounted in the corresponding rq's bucket.

Signed-off-by: Patrick Bellasi 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alessio Balsini 
Cc: Dietmar Eggemann 
Cc: Joel Fernandes 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Morten Rasmussen 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Quentin Perret 
Cc: Rafael J . Wysocki 
Cc: Steve Muckle 
Cc: Suren Baghdasaryan 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Todd Kjos 
Cc: Vincent Guittot 
Cc: Viresh Kumar 
Link: https://lkml.kernel.org/r/20190621084217.8167-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar

sysctl: define proc_do_static_key()

2019-06-15T03:18:27+00:00

Convert proc_dointvec_minmax_bpf_stats() into a more generic
helper, since we are going to use jump labels more often.

Note that sysctl_bpf_stats_enabled is removed, since
it is no longer needed/used.

Signed-off-by: Eric Dumazet 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman