The rest of the NUMA code expects an OF associativity property with
the first cell containing the length. Without this fix all topology changes
cause us to misparse the property and put the cpu into node 0.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The hypervisor uses unsigned 1 byte counters to signal topology changes to
the OS. Since they can wrap we need to check for any difference, not just if
the hypervisor count is greater than the previous count.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

VPHN supports up to 8 distance fields but the number of entries in
ibm,associativity-reference-points signifies how many are in use.
Don't look at all the VPHN counts, only distance_ref_points_depth
worth.

Since we already cap our distance metrics at MAX_DISTANCE_REF_POINTS,
use that to size the VPHN arrays and add a BUILD_BUG_ON to avoid it growing
larger than the VPHN maximum of 8.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Remove unnecessary variable initializations in VPHN functions.
Signed-off-by: NJesse Larrew <jlarrew@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Fix brace placement in VPHN code.
Signed-off-by: NJesse Larrew <jlarrew@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Correct a spelling error in VPHN comments in numa.c.
Signed-off-by: NJesse Larrew <jlarrew@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The header asm/hvcall.h was previously included indirectly via
smp.h. On non-SMP systems, however, these declarations are excluded
and the build breaks. This is easily fixed by including asm/hvcall.h
directly.

The VPHN feature is only meaningful on NUMA systems that implement
the SPLPAR option, so exclude the VPHN code on systems without
SPLPAR enabled.

Also, expose unmap_cpu_from_node() on systems with SPLPAR enabled,
even if CONFIG_HOTPLUG_CPU is disabled.

Lastly, map_cpu_to_node() is now needed by VPHN to manipulate the
node masks after boot time, so remove the __cpuinit annotation to
fix a section mismatch.
Signed-off-by: NJesse Larrew <jlarrew@linux.vnet.ibm.com>

This patch sets a timer during boot that will periodically poll the
associativity change counters in the VPA. When a change in
associativity is detected, it retrieves the new associativity domain
information via the H_HOME_NODE_ASSOCIATIVITY hcall and updates the
NUMA node maps and sysfs entries accordingly. Note that since the
ibm,associativity device tree property does not exist on configurations
with both NUMA and SPLPAR enabled, no device tree updates are necessary.
Signed-off-by: NJesse Larrew <jlarrew@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Add a function to get the maximum address that can be hotplug added.
This is needed to calculate the size of the tce table needed to cover
all memory in 1:1 mode.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We need to round memory regions correctly -- specifically, we need to
round reserved region in the more expansive direction (lower limit
down, upper limit up) whereas usable memory regions need to be rounded
in the more restrictive direction (lower limit up, upper limit down).

This introduces two set of inlines:

	memblock_region_memory_base_pfn()
	memblock_region_memory_end_pfn()
	memblock_region_reserved_base_pfn()
	memblock_region_reserved_end_pfn()

Although they are antisymmetric (and therefore are technically
duplicates) the use of the different inlines explicitly documents the
programmer's intention.

The lack of proper rounding caused a bug on ARM, which was then found
to also affect other architectures.
Reported-by: NRussell King <rmk@arm.linux.org.uk>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
LKML-Reference: <4CB4CDFD.4020105@kernel.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Oooops... we missed these. We incorrectly converted strings
used when parsing the device-tree on pseries, thus breaking
access to drconf memory and hotplug memory.

While at it, also revert some variable names that represent
something the FW calls "lmb" and thus don't need to be converted
to "memblock".
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
---

via following scripts

      FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

      sed -i \
        -e 's/lmb/memblock/g' \
        -e 's/LMB/MEMBLOCK/g' \
        $FILES

      for N in $(find . -name lmb.[ch]); do
        M=$(echo $N | sed 's/lmb/memblock/g')
        mv $N $M
      done

and remove some wrong change like lmbench and dlmb etc.

also move memblock.c from lib/ to mm/
Suggested-by: NIngo Molnar <mingo@elte.hu>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Form 1 affinity allows multiple entries in ibm,associativity-reference-points
which represent affinity domains in decreasing order of importance. The
Linux concept of a node is always the first entry, but using the other
values as an input to node_distance() allows the memory allocator to make
better decisions on which node to go first when local memory has been
exhausted.

We keep things simple and create an array indexed by NUMA node, capped at
4 entries. Each time we lookup an associativity property we initialise
the array which is overkill, but since we should only hit this path during
boot it didn't seem worth adding a per node valid bit.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

I've been told that the architected way to determine we are in form 1
affinity mode is by reading the ibm,architecture-vec-5 property which
mirrors the layout of the fifth vector of the ibm,client-architecture
structure.

Eventually we may want to parse the ibm,architecture-vec-5 and create
FW_FEATURE_* bits.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Convert NUMA code to new cpumask API. We shift the node to cpumask
setup code until after we complete bootmem allocation so we can
dynamically allocate the cpumasks.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Firmware changed the way it represents memory and cpu affinity on POWER7.
Unfortunately the old method now caps the topology to work around issues
with legacy operating systems. For Linux to get the correct topology we
need to use the new form 1 affinity information.

We set the form 1 field in the client architecture, and if we see "1" in the
ibm,associativity-form property firmware supports form 1 affinity and
we should look at the first field in the ibm,associativity-reference-points
array. If not we use the second field as we always have.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The macro any_online_node() is prone to producing sparse warnings due to
the local symbol 'node'.  Since all the in-tree users are really
requesting the first online node (the mask argument is either
NODE_MASK_ALL or node_online_map) just use the first_online_node macro and
remove the any_online_node macro since there are no users.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Milton Miller <miltonm@bga.com>
Cc: Nathan Fontenot <nfont@austin.ibm.com>
Cc: Geoff Levand <geoffrey.levand@am.sony.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Benny Halevy <bhalevy@panasas.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For some obscure reason, we only set init_bootmem_done after initializing
bootmem when NUMA isn't enabled. We even document this next to the declaration
of that global in system.h which of course I didn't read before I had to
debug why some WIP code wasn't working properly...

This patch changes it so that we always set it after bootmem is initialized
which should have always been the case... go figure !
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This patch reworks the hot_add_scn_to_nid and its supporting functions
to make them easier to understand.  There are no functional changes in
this patch and has been tested on machine with memory represented in the
device tree as memory nodes and in the ibm,dynamic-memory property.

My previous patch that introduced support for hotplug memory add on
systems whose memory was represented by the ibm,dynamic-memory property
of the device tree only left the code more unintelligible.  This
will hopefully makes things easier to understand.
Signed-off-by: NNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Fix the powerpc NUMA reserve bootmem page selection logic.

commit 8f64e1f2 (powerpc: Reserve
in bootmem lmb reserved regions that cross NUMA nodes) changed
the logic for how the powerpc LMB reserved regions were converted
to bootmen reserved regions.  As the folowing discussion reports,
the new logic was not correct.

mark_reserved_regions_for_nid() goes through each LMB on the
system that specifies a reserved area.  It searches for
active regions that intersect with that LMB and are on the
specified node.  It attempts to bootmem-reserve only the area
where the active region and the reserved LMB intersect.  We
can not reserve things on other nodes as they may not have
bootmem structures allocated, yet.

We base the size of the bootmem reservation on two possible
things.  Normally, we just make the reservation start and
stop exactly at the start and end of the LMB.

However, the LMB reservations are not aware of NUMA nodes and
on occasion a single LMB may cross into several adjacent
active regions.  Those may even be on different NUMA nodes
and will require separate calls to the bootmem reserve
functions.  So, the bootmem reservation must be trimmed to
fit inside the current active region.

That's all fine and dandy, but we trim the reservation
in a page-aligned fashion.  That's bad because we start the
reservation at a non-page-aligned address: physbase.

The reservation may only span 2 bytes, but that those bytes
may span two pfns and cause a reserve_size of 2*PAGE_SIZE.

Take the case where you reserve 0x2 bytes at 0x0fff and
where the active region ends at 0x1000.  You'll jump into
that if() statment, but node_ar.end_pfn=0x1 and
start_pfn=0x0.  You'll end up with a reserve_size=0x1000,
and then call

  reserve_bootmem_node(node, physbase=0xfff, size=0x1000);

0x1000 may not be on the same node as 0xfff.  Oops.

In almost all the vm code, end_<anything> is not inclusive.
If you have an end_pfn of 0x1234, page 0x1234 is not
included in the range.  Using PFN_UP instead of the
(>> >> PAGE_SHIFT) will make this consistent with the other VM
code.

We also need to do math for the reserved size with physbase
instead of start_pfn.  node_ar.end_pfn << PAGE_SHIFT is
*precisely* the end of the node.  However,
(start_pfn << PAGE_SHIFT) is *NOT* precisely the beginning
of the reserved area.  That is, of course, physbase.
If we don't use physbase here, the reserve_size can be
made too large.

From: Dave Hansen <dave@linux.vnet.ibm.com>
Tested-by: Geoff Levand <geoffrey.levand@am.sony.com>  Tested on PS3.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Use of_get_cpu_node, which is a superset of numa.c's find_cpu_node in
a less restrictive section (text vs cpuinit).
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

find_min_common_depth() was checking the property length incorrectly.
The value is in bytes not cells, and it is using the second entry.
Signed-off-By: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Both users of careful_allocation() immediately memset() the
result.  So, just do it in one place.

Also give careful_allocation() a 'z' prefix to bring it in
line with kzmalloc() and friends.
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Since we memset() the result in both of the uses here,
just make careful_alloc() return a virtual address.
Also, add a separate variable to store the physial
address that comes back from the lmb_alloc() functions.
This makes it less likely that someone will screw it up
forgetting to convert before returning since the vaddr
is always in a void* and the paddr is always in an
unsigned long.

I admit this is arbitrary since one of its users needs
a paddr and one a vaddr, but it does remove a good
number of casts.
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

If we fail a bootmem allocation, the bootmem code itself
panics.  No need to redo it here.

Also change the wording of the other panic.  We don't
strictly have to allocate memory on the specified node.
It is just a hint and that node may not even *have* any
memory on it.  In that case we can and do fall back to
other nodes.
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The behavior in careful_allocation() really confused me
at first.  Add a comment to hopefully make it easier
on the next doofus that looks at it.
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

careful_allocation() was calling into the bootmem allocator for
nodes which had not been fully initialized and caused a previous
bug:  http://patchwork.ozlabs.org/patch/10528/  So, I merged a
few broken out loops in do_init_bootmem() to fix it.  That changed
the code ordering.

I think this bug is triggered by having reserved areas for a node
which are spanned by another node's contents.  In the
mark_reserved_regions_for_nid() code, we attempt to reserve the
area for a node before we have allocated the NODE_DATA() for that
nid.  We do this since I reordered that loop.  I suck.

This is causing crashes at bootup on some systems, as reported
by Jon Tollefson.

This may only present on some systems that have 16GB pages
reserved.  But, it can probably happen on any system that is
trying to reserve large swaths of memory that happen to span other
nodes' contents.

This commit ensures that we do not touch bootmem for any node which
has not been initialized, and also removes a compile warning about
an unused variable.
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

I got a bug report about a distro kernel not booting on a particular
machine.  It would freeze during boot:

> ...
> Could not find start_pfn for node 1
> [boot]0015 Setup Done
> Built 2 zonelists in Node order, mobility grouping on.  Total pages: 123783
> Policy zone: DMA
> Kernel command line:
> [boot]0020 XICS Init
> [boot]0021 XICS Done
> PID hash table entries: 4096 (order: 12, 32768 bytes)
> clocksource: timebase mult[7d0000] shift[22] registered
> Console: colour dummy device 80x25
> console handover: boot [udbg0] -> real [hvc0]
> Dentry cache hash table entries: 1048576 (order: 7, 8388608 bytes)
> Inode-cache hash table entries: 524288 (order: 6, 4194304 bytes)
> freeing bootmem node 0

I've reproduced this on 2.6.27.7.  It is caused by commit
8f64e1f2 ("powerpc: Reserve in bootmem
lmb reserved regions that cross NUMA nodes").

The problem is that Jon took a loop which was (in pseudocode):

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
		reserve_node_bootmem(nid);

and broke it up into:

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
	for_each_node(nid)
		reserve_node_bootmem(nid);

The issue comes in when the 'careful_alloc()' is called on a node with
no memory.  It falls back to using bootmem from a previously-initialized
node.  But, bootmem has not yet been reserved when Jon's patch is
applied.  It gives back bogus memory (0xc000000000000000) and pukes
later in boot.

The following patch collapses the loop back together.  It also breaks
the mark_reserved_regions_for_nid() code out into a function and adds
some comments.  I think a huge part of introducing this bug is because
for loop was too long and hard to read.

The actual bug fix here is the:

+		if (end_pfn <= node->node_start_pfn ||
+		    start_pfn >= node_end_pfn)
+			continue;
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

numa_enforce_memory_limit tried to be smart and only call lmb_end_of_DRAM
when a memory limit was set via mem= on the command line.  However,
the early boot code will also limit memory added to the lmb system
when iommu=off is specified.  When this happens, the page allocator
is given pages not in the linear mapping and this results in a fatal
data reference to the unmapped page.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Adjust amount to reserve based on previous nodes for reserves spanning
multiple nodes. Check if the node active range is empty before attempting
to pass the reserve to bootmem.  In practice the range shouldn't be empty,
but to be sure we check.
Signed-off-by: NJon Tollefson <kniht@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

If there are multiple reserved memory blocks via lmb_reserve() that are
contiguous addresses and on different NUMA nodes we are losing track of which
address ranges to reserve in bootmem on which node.  I discovered this
when I recently got to try 16GB huge pages on a system with more then 2 nodes.

When scanning the device tree in early boot we call lmb_reserve() with
the addresses of the 16G pages that we find so that the memory doesn't
get used for something else.  For example the addresses for the pages
could be 4000000000, 4400000000, 4800000000, 4C00000000, etc - 8 pages,
one on each of eight nodes.  In the lmb after all the pages have been
reserved it will look something like the following:

lmb_dump_all:
    memory.cnt            = 0x2
    memory.size           = 0x3e80000000
    memory.region[0x0].base       = 0x0
                      .size     = 0x1e80000000
    memory.region[0x1].base       = 0x4000000000
                      .size     = 0x2000000000
    reserved.cnt          = 0x5
    reserved.size         = 0x3e80000000
    reserved.region[0x0].base       = 0x0
                      .size     = 0x7b5000
    reserved.region[0x1].base       = 0x2a00000
                      .size     = 0x78c000
    reserved.region[0x2].base       = 0x328c000
                      .size     = 0x43000
    reserved.region[0x3].base       = 0xf4e8000
                      .size     = 0xb18000
    reserved.region[0x4].base       = 0x4000000000
                      .size     = 0x2000000000

The reserved.region[0x4] contains the 16G pages.  In
arch/powerpc/mm/num.c: do_init_bootmem() we loop through each of the
node numbers looking for the reserved regions that belong to the
particular node.  It is not able to identify region 0x4 as being a part
of each of the 8 nodes.  It is assuming that a reserved region is only
on a single node.

This patch takes out the reserved region loop from inside
the loop that goes over each node.  It looks up the active region containing
the start of the reserved region.  If it extends past that active region then
it adjusts the size and gets the next active region containing it.
Signed-off-by: NJon Tollefson <kniht@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Kdump kernel needs to use only those memory regions that it is allowed
to use (crashkernel, rtas, tce, etc.).  Each of these regions have
their own sizes and are currently added under 'linux,usable-memory'
property under each memory@xxx node of the device tree.

The ibm,dynamic-memory property of ibm,dynamic-reconfiguration-memory
node (on POWER6) now stores in it the representation for most of the
logical memory blocks with the size of each memory block being a
constant (lmb_size).  If one or more or part of the above mentioned
regions lie under one of the lmb from ibm,dynamic-memory property,
there is a need to identify those regions within the given lmb.

This makes the kernel recognize a new 'linux,drconf-usable-memory'
property added by kexec-tools.  Each entry in this property is of the
form of a count followed by that many (base, size) pairs for the above
mentioned regions.  The number of cells in the count value is given by
the #size-cells property of the root node.
Signed-off-by: NChandru Siddalingappa <chandru@in.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

There are a lot of places that define either a single bootmem descriptor or an
array of them.  Use only one central array with MAX_NUMNODES items instead.
Signed-off-by: NJohannes Weiner <hannes@saeurebad.de>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the association of a memory section with a numa node that
occurs during hotplug add of a memory section.  This adds a check in
the hot_add_scn_to_nid() routine for the
ibm,dynamic-reconfiguration-memory node in the device tree.  If
present the new hot_add_drconf_scn_to_nid() routine is invoked, which
can properly parse the ibm,dynamic-reconfiguration-memory node of the
device tree and make the proper numa node associations.

This also introduces the valid_hot_add_scn() routine as a helper
function for code that is common to the hot_add_scn_to_nid() and
hot_add_drconf_scn_to_nid() routines.
Signed-off-by: NNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This splits off several pieces of code that parse the
ibm,dynamic-reconfiguration-memory node of the device tree into separate
helper routines.  This is in preparation for the next commit that will
use these helper routines.  There are no functional changes in this patch.
Signed-off-by: NNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

numa.c requires routines declared in linux/of.h, so should include it.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patchset adds a flags variable to reserve_bootmem() and uses the
BOOTMEM_EXCLUSIVE flag in crashkernel reservation code to detect collisions
between crashkernel area and already used memory.

This patch:

Change the reserve_bootmem() function to accept a new flag BOOTMEM_EXCLUSIVE.
If that flag is set, the function returns with -EBUSY if the memory already
has been reserved in the past.  This is to avoid conflicts.

Because that code runs before SMP initialisation, there's no race condition
inside reserve_bootmem_core().

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix powerpc build]
Signed-off-by: NBernhard Walle <bwalle@suse.de>
Cc: <linux-arch@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>