ARM: Initialize ptl->lock for vector page

Without this patch, ARM can not use SPLIT_PTLOCK_CPUS if
PREEMPT_RT_FULL=y because vectors_user_mapping() creates a
VM_ALWAYSDUMP mapping of the vector page (address 0xffff0000), but no
ptl->lock has been allocated for the page.  An attempt to coredump
that page will result in a kernel NULL pointer dereference when
follow_page() attempts to lock the page.

The call tree to the NULL pointer dereference is:

   do_notify_resume()
      get_signal_to_deliver()
         do_coredump()
            elf_core_dump()
               get_dump_page()
                  __get_user_pages()
                     follow_page()
                        pte_offset_map_lock() <----- a #define
                           ...
                              rt_spin_lock()

The underlying problem is exposed by mm-shrink-the-page-frame-to-rt-size.patch.

Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Frank <Frank_Rowand@sonyusa.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/4E87C535.2030907@am.sony.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
mm: Allow only slab on RT

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
radix-tree-rt-aware.patch

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
panic-disable-random-on-rt
ipc: Make the ipc code -rt aware

RT serializes the code with the (rt)spinlock but keeps preemption
enabled. Some parts of the code need to be atomic nevertheless.

Protect it with preempt_disable/enable_rt pairts.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
ipc/mqueue: Add a critical section to avoid a deadlock

(Repost for v3.0-rt1 and changed the distination addreses)
I have tested the following patch on v3.0-rt1 with PREEMPT_RT_FULL.
In POSIX message queue, if a sender process uses SCHED_FIFO and
has a higher priority than a receiver process, the sender will
be stuck at ipc/mqueue.c:452

  452                 while (ewp->state == STATE_PENDING)
  453                         cpu_relax();

Description of the problem
 (receiver process)
   1. receiver changes sender's state to STATE_PENDING (mqueue.c:846)
   2. wake up sender process and "switch to sender" (mqueue.c:847)
      Note: This context switch only happens in PREEMPT_RT_FULL kernel.
 (sender process)
   3. sender check the own state in above loop (mqueue.c:452-453)
   *. receiver will never wake up and cannot change sender's state to
      STATE_READY because sender has higher priority

Signed-off-by: Yoshitake Kobayashi <yoshitake.kobayashi@toshiba.co.jp>
Cc: viro@zeniv.linux.org.uk
Cc: dchinner@redhat.com
Cc: npiggin@kernel.dk
Cc: hch@lst.de
Cc: arnd@arndb.de
Link: http://lkml.kernel.org/r/4E2A38A0.1090601@toshiba.co.jp
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
relay: fix timer madness

remove timer calls (!!!) from deep within the tracing infrastructure.
This was totally bogus code that can cause lockups and worse.  Poll
the buffer every 2 jiffies for now.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
net-ipv4-route-use-locks-on-up-rt.patch

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>