commit f5252e009d5b87071a919221e4f6624184005368 upstream

The /proc/vmallocinfo shows information about vmalloc allocations in vmlist
that is a linklist of vm_struct. It, however, may access pages field of
vm_struct where a page was not allocated. This results in a null pointer
access and leads to a kernel panic.

Why this happen:
In __vmalloc_node() called from vmalloc(), newly allocated vm_struct
is added to vmlist at __get_vm_area_node() and then, some fields of
vm_struct such as nr_pages and pages are set at __vmalloc_area_node(). In
other words, it is added to vmlist before it is fully initialized. At the
same time, when the /proc/vmallocinfo is read, it accesses the pages field
of vm_struct according to the nr_pages field at show_numa_info(). Thus, a
null pointer access happens.

Patch:
This patch adds newly allocated vm_struct to the vmlist *after* it is fully
initialized. So, it can avoid accessing the pages field with unallocated
page when show_numa_info() is called.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

No matching upstream commit as it was resolved differently there.


pcpu_get_vm_areas() is used only when dynamic percpu allocator is used
by the architecture.  In 2.6.32, ia64 doesn't use dynamic percpu
allocator and has a macro which makes pcpu_get_vm_areas() buggy via
local/global variable aliasing and triggers compile warning.

The problem is fixed in upstream and ia64 uses dynamic percpu
allocators, so the only left issue is inclusion of unnecessary code
and compile warning on ia64 on 2.6.32.

Don't build pcpu_get_vm_areas() if legacy percpu allocator is in use.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

To directly use spread NUMA memories for percpu units, percpu
allocator will be updated to allow sparsely mapping units in a chunk.
As the distances between units can be very large, this makes
allocating single vmap area for each chunk undesirable.  This patch
implements pcpu_get_vm_areas() and pcpu_free_vm_areas() which
allocates and frees sparse congruent vmap areas.

pcpu_get_vm_areas() take @offsets and @sizes array which define
distances and sizes of vmap areas.  It scans down from the top of
vmalloc area looking for the top-most address which can accomodate all
the areas.  The top-down scan is to avoid interacting with regular
vmallocs which can push up these congruent areas up little by little
ending up wasting address space and page table.

To speed up top-down scan, the highest possible address hint is
maintained.  Although the scan is linear from the hint, given the
usual large holes between memory addresses between NUMA nodes, the
scanning is highly likely to finish after finding the first hole for
the last unit which is scanned first.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <npiggin@suse.de>

Conflicts:
	arch/x86/include/asm/pgtable.h

Impact: allow larger alignment for early vmalloc area allocation

Some early vmalloc users might want larger alignment, for example, for
custom large page mapping.  Add @align to vm_area_register_early().
While at it, drop docbook comment on non-existent @size.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>

Impact: two more public map/unmap functions

Implement map_kernel_range_noflush() and unmap_kernel_range_noflush().
These functions respectively map and unmap address range in kernel VM
area but doesn't do any vcache or tlb flushing.  These will be used by
new percpu allocator.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>

Impact: allow multiple early vm areas

There are places where kernel VM area needs to be allocated before
vmalloc is initialized.  This is done by allocating static vm_struct,
initializing several fields and linking it to vmlist and later vmalloc
initialization picking up these from vmlist.  This is currently done
manually and if there's more than one such areas, there's no defined
way to arbitrate who gets which address.

This patch implements vm_area_register_early(), which takes vm_area
struct with flags and size initialized, assigns address to it and puts
it on the vmlist.  This way, multiple early vm areas can determine
which addresses they should use.  The only current user - alpha mm
init - is converted to use it.

Signed-off-by: Tejun Heo <tj@kernel.org>

We have get_vm_area_caller() and __get_vm_area() but not
__get_vm_area_caller()

On powerpc, I use __get_vm_area() to separate the ranges of addresses
given to vmalloc vs.  ioremap (various good reasons for that) so in order
to be able to implement the new caller tracking in /proc/vmallocinfo, I
need a "_caller" variant of it.

(akpm: needed for ongoing powerpc development, so merge it early)

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Sparse output following warnings.

mm/vmalloc.c:1436:6: warning: symbol 'vread' was not declared. Should it be static?
mm/vmalloc.c:1474:6: warning: symbol 'vwrite' was not declared. Should it be static?

However, it is used by /dev/kmem. fixed here.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>