As noted in 83d349f35e1ae72268c5104dbf9ab2ae635425d4 ("x86: don't send
an IPI to the empty set of CPU's"), some APIC's will be very unhappy
with an empty destination mask.  That commit added a WARN_ON() for that
case, and avoided the resulting problem, but didn't fix the underlying
reason for why those empty mask cases happened.

This fixes that, by checking the result of 'cpumask_andnot()' of the
current CPU actually has any other CPU's left in the set of CPU's to be
sent a TLB flush, and not calling down to the IPI code if the mask is
empty.

The reason this started happening at all is that we started passing just
the CPU mask pointers around in commit 4595f9620 ("x86: change
flush_tlb_others to take a const struct cpumask"), and when we did that,
the cpumask was no longer thread-local.

Before that commit, flush_tlb_mm() used to create it's own copy of
'mm->cpu_vm_mask' and pass that copy down to the low-level flush
routines after having tested that it was not empty.  But after changing
it to just pass down the CPU mask pointer, the lower level TLB flush
routines would now get a pointer to that 'mm->cpu_vm_mask', and that
could still change - and become empty - after the test due to other
CPU's having flushed their own TLB's.

See

	http://bugzilla.kernel.org/show_bug.cgi?id=13933

for details.

Tested-by: Thomas Björnell <thomas.bjornell@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The default_send_IPI_mask_logical() function uses the "flat" APIC mode
to send an IPI to a set of CPU's at once, but if that set happens to be
empty, some older local APIC's will apparently be rather unhappy.  So
just warn if a caller gives us an empty mask, and ignore it.

This fixes a regression in 2.6.30.x, due to commit 4595f9620 ("x86:
change flush_tlb_others to take a const struct cpumask"), documented
here:

	http://bugzilla.kernel.org/show_bug.cgi?id=13933

which causes a silent lock-up.  It only seems to happen on PPro, P2, P3
and Athlon XP cores.  Most developers sadly (or not so sadly, if you're
a developer..) have more modern CPU's.  Also, on x86-64 we don't use the
flat APIC mode, so it would never trigger there even if the APIC didn't
like sending an empty IPI mask.

Reported-by: Pavel Vilim <wylda@volny.cz>
Reported-and-tested-by: Thomas Björnell <thomas.bjornell@gmail.com>
Reported-and-tested-by: Martin Rogge <marogge@onlinehome.de>
Cc: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'next' of git://git.monstr.eu/linux-2.6-microblaze:
  microblaze: Update Microblaze defconfigs
  microblaze: Use klimit instead of _end for memory init
  microblaze: Enable ppoll syscall
  microblaze: Sane handling of missing timer/intc in device tree
  microblaze: use the generic ack_bad_irq implementation

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu: use the right flag for get_vm_area()
  percpu, sparc64: fix sparse possible cpu map handling
  init: set nr_cpu_ids before setup_per_cpu_areas()

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, mce: Don't initialize MCEs on unknown CPUs
  x86, mce: don't log boot MCEs on Pentium M (model == 13) CPUs
  x86: Annotate section mismatch warnings in kernel/apic/x2apic_uv_x.c
  x86, mce: therm_throt: Don't log redundant normality
  x86: Fix UV BAU destination subnode id

* 'sh/for-2.6.31' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6:
  sh: sh7724 ddr self-refresh changes
  sh: use in-soc KEYSC on se7724
  sh: CMT suspend/resume
  sh: skip disabled LCDC channels

Signed-off-by: Michal Simek <monstr@monstr.eu>

For noMMU system when you use larger rootfs image
there is problem with using _end label because
we increase klimit but in memory initialization
we use still _end which is wrong. Larger mtd rootfs
was rewritten by init_bootmem_node.

MMU kernel use static initialization where klimit
is setup to _end. There is no any other hanling
with klimit.

Signed-off-by: Michal Simek <monstr@monstr.eu>

Signed-off-by: Michal Simek <monstr@monstr.eu>

This code path doesn't test any returned pointers for NULL, leading to a bad
kernel page fault if there's no timer/intc found.

Slightly better is to BUG(), but even better still would be a printk beforehand.

Signed-off-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>