linux-toradex.git/Documentation/sysctl, branch v3.5-rc6

mqueue: separate mqueue default value from maximum value

2012-06-01T00:49:31+00:00

Commit b231cca4381e ("message queues: increase range limits") changed
mqueue default value when attr parameter is specified NULL from hard
coded value to fs.mqueue.{msg,msgsize}_max sysctl value.

This made large side effect.  When user need to use two mqueue
applications 1) using !NULL attr parameter and it require big message
size and 2) using NULL attr parameter and only need small size message,
app (1) require to raise fs.mqueue.msgsize_max and app (2) consume large
memory size even though it doesn't need.

Doug Ledford propsed to switch back it to static hard coded value.
However it also has a compatibility problem.  Some applications might
started depend on the default value is tunable.

The solution is to separate default value from maximum value.

Signed-off-by: KOSAKI Motohiro 
Signed-off-by: Doug Ledford 
Acked-by: Doug Ledford 
Acked-by: Joe Korty 
Cc: Amerigo Wang 
Acked-by: Serge E. Hallyn 
Cc: Jiri Slaby 
Cc: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

net: doc: merge /proc/sys/net/core/* documents into one place

2012-04-27T04:09:26+00:00

All parameter descriptions in /proc/sys/net/core/* now is separated
two places. So, merge them into Documentation/sysctl/net.txt.

Signed-off-by: Shan Wei 
Signed-off-by: David S. Miller

Documentation: add missing tainted bits to Documentation/sysctl/kernel.txt

2012-02-07T00:29:19+00:00

Two of the bits in the tainted flag are not documented.

Signed-off-by: Larry Finger 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

sysctl: add the kernel.ns_last_pid control

2012-01-13T04:13:11+00:00

The sysctl works on the current task's pid namespace, getting and setting
its last_pid field.

Writing is allowed for CAP_SYS_ADMIN-capable tasks thus making it possible
to create a task with desired pid value.  This ability is required badly
for the checkpoint/restore in userspace.

This approach suits all the parties for now.

Signed-off-by: Pavel Emelyanov 
Acked-by: Tejun Heo 
Cc: Oleg Nesterov 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Cc: Serge Hallyn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86: Panic on detection of stack overflow

2011-12-05T10:37:47+00:00

Currently, messages are just output on the detection of stack
overflow, which is not sufficient for systems that need a
high reliability. This is because in general the overflow may
corrupt data, and the additional corruption may occur due to
reading them unless systems stop.

This patch adds the sysctl parameter
kernel.panic_on_stackoverflow and causes a panic when detecting
the overflows of kernel, IRQ and exception stacks except user
stack according to the parameter. It is disabled by default.

Signed-off-by: Mitsuo Hayasaka 
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Randy Dunlap 
Cc: "H. Peter Anvin" 
Link: http://lkml.kernel.org/r/20111129060836.11076.12323.stgit@ltc219.sdl.hitachi.co.jp
Signed-off-by: Ingo Molnar

kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel

2011-11-01T00:30:53+00:00

Userspace needs to know the highest valid capability of the running
kernel, which right now cannot reliably be retrieved from the header files
only.  The fact that this value cannot be determined properly right now
creates various problems for libraries compiled on newer header files
which are run on older kernels.  They assume capabilities are available
which actually aren't.  libcap-ng is one example.  And we ran into the
same problem with systemd too.

Now the capability is exported in /proc/sys/kernel/cap_last_cap.

[akpm@linux-foundation.org: make cap_last_cap const, per Ulrich]
Signed-off-by: Dan Ballard 
Cc: Randy Dunlap 
Cc: Ingo Molnar 
Cc: Lennart Poettering 
Cc: Kay Sievers 
Cc: Ulrich Drepper 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: introduce shm_rmid_forced sysctl

2011-07-26T23:49:44+00:00

Add support for the shm_rmid_forced sysctl.  If set to 1, all shared
memory objects in current ipc namespace will be automatically forced to
use IPC_RMID.

The POSIX way of handling shmem allows one to create shm objects and
call shmdt(), leaving shm object associated with no process, thus
consuming memory not counted via rlimits.

With shm_rmid_forced=1 the shared memory object is counted at least for
one process, so OOM killer may effectively kill the fat process holding
the shared memory.

It obviously breaks POSIX - some programs relying on the feature would
stop working.  So set shm_rmid_forced=1 only if you're sure nobody uses
"orphaned" memory.  Use shm_rmid_forced=0 by default for compatability
reasons.

The feature was previously impemented in -ow as a configure option.

[akpm@linux-foundation.org: fix documentation, per Randy]
[akpm@linux-foundation.org: fix warning]
[akpm@linux-foundation.org: readability/conventionality tweaks]
[akpm@linux-foundation.org: fix shm_rmid_forced/shm_forced_rmid confusion, use standard comment layout]
Signed-off-by: Vasiliy Kulikov 
Cc: Randy Dunlap 
Cc: "Eric W. Biederman" 
Cc: "Serge E. Hallyn" 
Cc: Daniel Lezcano 
Cc: Oleg Nesterov 
Cc: Tejun Heo 
Cc: Ingo Molnar 
Cc: Alan Cox 
Cc: Solar Designer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: refresh sysctl/kernel.txt

2011-07-23T17:58:08+00:00

Refresh sysctl/kernel.txt.  More specifically,

 - drop stale index entries
 - sync and sort index and entries
 - reflow sticking out paragraphs to colwidth 72
 - correct typos
 - cleanup whitespace

Signed-off-by: Borislav Petkov 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

coredump: add support for exe_file in core name

2011-05-27T00:12:36+00:00

Now, exe_file is not proc FS dependent, so we can use it to name core
file.  So we add %E pattern for core file name cration which extract path
from mm_struct->exe_file.  Then it converts slashes to exclamation marks
and pastes the result to the core file name itself.

This is useful for environments where binary names are longer than 16
character (the current->comm limitation).  Also where there are binaries
with same name but in a different path.  Further in case the binery itself
changes its current->comm after exec.

So by doing (s/$/#/ -- # is treated as git comment):

  $ sysctl kernel.core_pattern='core.%p.%e.%E'
  $ ln /bin/cat cat45678901234567890
  $ ./cat45678901234567890
  ^Z
  $ rm cat45678901234567890
  $ fg
  ^\Quit (core dumped)
  $ ls core*

we now get:

  core.2434.cat456789012345.!root!cat45678901234567890 (deleted)

Signed-off-by: Jiri Slaby 
Cc: Al Viro 
Cc: Alan Cox 
Reviewed-by: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: update epoll sysctl text

2011-05-23T22:14:11+00:00

max_user_instances was removed in this commit:

   commit 9df04e1f25effde823a600e755b51475d438f56b
   Author: Davide Libenzi 
   Date:   Thu Jan 29 14:25:26 2009 -0800

    epoll: drop max_user_instances and rely only on max_user_watches

but the documentation entry was not removed.

Cc: Davide Libenzi 
Signed-off-by: Lucian Adrian Grijincu 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds