linux-toradex.git/Documentation/filesystems/proc.txt, branch v4.9.120

fs/proc: Stop trying to report thread stacks

2016-10-20T07:21:41+00:00

This reverts more of:

  b76437579d13 ("procfs: mark thread stack correctly in proc//maps")

... which was partially reverted by:

  65376df58217 ("proc: revert /proc//maps [stack:TID] annotation")

Originally, /proc/PID/task/TID/maps was the same as /proc/TID/maps.

In current kernels, /proc/PID/maps (or /proc/TID/maps even for
threads) shows "[stack]" for VMAs in the mm's stack address range.

In contrast, /proc/PID/task/TID/maps uses KSTK_ESP to guess the
target thread's stack's VMA.  This is racy, probably returns garbage
and, on arches with CONFIG_TASK_INFO_IN_THREAD=y, is also crash-prone:
KSTK_ESP is not safe to use on tasks that aren't known to be running
ordinary process-context kernel code.

This patch removes the difference and just shows "[stack]" for VMAs
in the mm's stack range.  This is IMO much more sensible -- the
actual "stack" address really is treated specially by the VM code,
and the current thread stack isn't even well-defined for programs
that frequently switch stacks on their own.

Reported-by: Jann Horn 
Signed-off-by: Andy Lutomirski 
Acked-by: Thomas Gleixner 
Cc: Al Viro 
Cc: Andrew Morton 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Johannes Weiner 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Linux API 
Cc: Peter Zijlstra 
Cc: Tycho Andersen 
Link: http://lkml.kernel.org/r/3e678474ec14e0a0ec34c611016753eea2e1b8ba.1475257877.git.luto@kernel.org
Signed-off-by: Ingo Molnar

Documentation/filesystems/proc.txt: add more description for maps/smaps

2016-10-08T01:46:30+00:00

Add some more description on the limitations for smaps/maps readings, as
well as some guaruntees we can make.

Link: http://lkml.kernel.org/r/1475296958-27652-2-git-send-email-robert.hu@intel.com
Signed-off-by: Robert Ho 
Acked-by: Michal Hocko 
Cc: Dave Hansen 
Cc: Xiao Guangrong 
Cc: Robert Hu 
Cc: Oleg Nesterov 
Cc: Paolo Bonzini 
Cc: Dan Williams 
Cc: Gleb Natapov 
Cc: Marcelo Tosatti 
Cc: Stefan Hajnoczi 
Cc: Ross Zwisler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/filesystems: Fixed typo

2016-09-16T15:51:34+00:00

Fixed a -> an typo.

Signed-off-by: Robert Foss 
Acked-by: Kees Cook 
Signed-off-by: Jonathan Corbet

thp: update Documentation/{vm/transhuge,filesystems/proc}.txt

2016-07-26T23:19:19+00:00

Add info about tmpfs/shmem with huge pages.

Link: http://lkml.kernel.org/r/1466021202-61880-38-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

irq/Documentation: Correct result of echnoing 5 to smp_affinity

2016-07-10T14:55:04+00:00

This command:

  echo 5 > /proc/irq/10/smp_affinity

means only the first and third (not fourth) CPUs can handle irqs
That is, CPU0 is the first CPU and CPU2 is the third cpu

Signed-off-by: John Kacur 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1466168715-8410-1-git-send-email-jkacur@redhat.com
Signed-off-by: Ingo Molnar

procfs: expose umask in /proc//status

2016-05-21T00:58:30+00:00

It's not possible to read the process umask without also modifying it,
which is what umask(2) does.  A library cannot read umask safely,
especially if the main program might be multithreaded.

Add a new status line ("Umask") in /proc//status.  It contains the
file mode creation mask (umask) in octal.  It is only shown for tasks
which have task->fs.

This patch is adapted from one originally written by Pierre Carrier.

The use case is that we have endless trouble with people setting weird
umask() values (usually on the grounds of "security"), and then
everything breaking.  I'm on the hook to fix these.  We'd like to add
debugging to our program so we can dump out the umask in debug reports.

Previous versions of the patch used a syscall so you could only read
your own umask.  That's all I need.  However there was quite a lot of
push-back from those, so this new version exports it in /proc.

See:
  https://lkml.org/lkml/2016/4/13/704 [umask2]
  https://lkml.org/lkml/2016/4/13/487 [getumask]

Signed-off-by: Richard W.M. Jones 
Acked-by: Konstantin Khlebnikov 
Acked-by: Jerome Marchand 
Acked-by: Kees Cook 
Cc: "Theodore Ts'o" 
Cc: Michal Hocko 
Cc: Pierre Carrier 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: add /proc//timerslack_ns interface

2016-03-17T22:09:34+00:00

This patch provides a proc/PID/timerslack_ns interface which exposes a
task's timerslack value in nanoseconds and allows it to be changed.

This allows power/performance management software to set timer slack for
other threads according to its policy for the thread (such as when the
thread is designated foreground vs.  background activity)

If the value written is non-zero, slack is set to that value.  Otherwise
sets it to the default for the thread.

This interface checks that the calling task has permissions to to use
PTRACE_MODE_ATTACH_FSCREDS on the target task, so that we can ensure
arbitrary apps do not change the timer slack for other apps.

Signed-off-by: John Stultz 
Acked-by: Kees Cook 
Cc: Arjan van de Ven 
Cc: Thomas Gleixner 
Cc: Oren Laadan 
Cc: Ruchi Kandoi 
Cc: Rom Lemarchand 
Cc: Android Kernel Team 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: polish virtual memory accounting

2016-02-03T16:28:43+00:00

* add VM_STACK as alias for VM_GROWSUP/DOWN depending on architecture
* always account VMAs with flag VM_STACK as stack (as it was before)
* cleanup classifying helpers
* update comments and documentation

Signed-off-by: Konstantin Khlebnikov 
Tested-by: Sudip Mukherjee 
Cc: Cyrill Gorcunov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: revert /proc//maps [stack:TID] annotation

2016-02-03T16:28:43+00:00

Commit b76437579d13 ("procfs: mark thread stack correctly in
proc//maps") added [stack:TID] annotation to /proc//maps.

Finding the task of a stack VMA requires walking the entire thread list,
turning this into quadratic behavior: a thousand threads means a
thousand stacks, so the rendering of /proc//maps needs to look at a
million combinations.

The cost is not in proportion to the usefulness as described in the
patch.

Drop the [stack:TID] annotation to make /proc//maps (and
/proc//numa_maps) usable again for higher thread counts.

The [stack] annotation inside /proc//task//maps is retained, as
identifying the stack VMA there is an O(1) operation.

Siddesh said:
 "The end users needed a way to identify thread stacks programmatically and
  there wasn't a way to do that.  I'm afraid I no longer remember (or have
  access to the resources that would aid my memory since I changed
  employers) the details of their requirement.  However, I did do this on my
  own time because I thought it was an interesting project for me and nobody
  really gave any feedback then as to its utility, so as far as I am
  concerned you could roll back the main thread maps information since the
  information is available in the thread-specific files"

Signed-off-by: Johannes Weiner 
Cc: "Kirill A. Shutemov" 
Cc: Siddhesh Poyarekar 
Cc: Shaohua Li 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'docs-4.5' of git://git.lwn.net/linux

2016-01-17T19:55:07+00:00

Pull documentation updates from Jon Corbet:
 "A relatively boring cycle in the docs tree.  There's a few kernel-doc
  fixes and various document tweaks.

  One patch reaches out of the documentation subtree to fix a comment in
  init/do_mounts_rd.c.  There didn't seem to be anybody more appropriate
  to take that one, so I accepted it"

* tag 'docs-4.5' of git://git.lwn.net/linux: (29 commits)
  thermal: add description for integral_cutoff unit
  Documentation: update libhugetlbfs site url
  Documentation: Explain pci=conf1,conf2 more verbosely
  DMA-API: fix confusing sentence in Documentation/DMA-API.txt
  Documentation: translations: update linux cross reference link
  Documentation: fix typo in CodingStyle
  init, Documentation: Remove ramdisk_blocksize mentions
  Documentation-getdelays: Apply a recommendation from "checkpatch.pl" in main()
  Documentation: HOWTO: update versions from 3.x to 4.x
  Documentation: remove outdated references from translations
  Doc: treewide: Fix grammar "a" to "an"
  Documentation: cpu-hotplug: Fix sysfs mount instructions
  can-doc: Add hint about getting timestamps
  Fix CFQ I/O scheduler parameter name in documentation
  Documentation: arm: remove dead links from Marvell Berlin docs
  Documentation: HOWTO: update code cross reference link
  Doc: Docbook/iio: Fix typo in iio.tmpl
  DocBook: make index.html generation less verbose by default
  DocBook: Cleanup: remove an unused $(call) line
  DocBook: Add a help message for DOCBOOKS env var
  ...