[PATCH 0/4 v6] max_threadx handling

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

In fork_init a division by zero may occur.

In the first patch the calculation of max_threads is moved from fork_init
to a new separate function.

The incorrect calculation of max threads is addressed in the 
second patch.

Furthermore max_threads is checked against FUTEX_TID_MASK.

The third patch addresses max_threads being set by writing to
/proc/sys/kernel/threads-max. The same limits are applied as
in fork_init.

The fourth patch adds a description of threads-max to
Documentation/sysctl/kernel.txt.

New in version 6:
  Check against overflow of totalram_pages * PAGE_SIZE.
  Introduce argument of set_max_threads in 3rd patch where it is needed,
  not before.
  Update Documentation/sysctl/kernel.txt concerning threads-max.

New in version 5:
  Do not update limits of the init process
  Do not update max_threads on memory hotplug events
  Corrections to commit messages

New in version 4:
  Separation of refactoring and correction into separate patches
  (as requested by Ingo Molnar)
  Remove redundant argument of fork_init

New in version 3:
  Determination of max_threads moved to separate function.
  Handling of /proc/sys/kernel/threads-max
  Handling of memory hotplugging.

New in version 2:
  Use div64_u64 for 64-bit division.

Thank you for your helpful feedback:
  Andrew Morton <akpm@linux-foundation.org>
  David Rientjes <rientjes@google.com>
  Guenter Roeck <linux@roeck-us.net>
  Ingo Molnar <mingo@kernel.org>
  Oleg Nesterov <oleg@redhat.com>
  Peter Zijlstra <peterz@infradead.org>
  Vladimir Davydov <vdavydov@parallels.com>

Heinrich Schuchardt (4):
  kernel/fork.c: new function for max_threads
  kernel/fork.c: avoid division by zero
  kernel/sysctl.c: threads-max observe limits
  Doc/sysctl/kernel.txt: document threads-max

 Documentation/sysctl/kernel.txt | 21 +++++++++++
 include/linux/sysctl.h          |  3 ++
 init/main.c                     |  4 +--
 kernel/fork.c                   | 78 ++++++++++++++++++++++++++++++++++-------
 kernel/sysctl.c                 |  6 ++--
 5 files changed, 93 insertions(+), 19 deletions(-)

-- 
2.1.4