arm64: kdump: no need to mark crashkernel pages manually PG_reserved

The crashkernel is reserved via memblock_reserve().  memblock_free_all()
will call free_low_memory_core_early(), which will go over all reserved
memblocks, marking the pages as PG_reserved.

So manually marking pages as PG_reserved is not necessary, they are
already in the desired state (otherwise they would have been handed over
to the buddy as free pages and bad things would happen).

Link: http://lkml.kernel.org/r/20190114125903.24845-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Greg Hackmann <ghackmann@android.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: CHANDAN VN <chandan.vn@samsung.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/kernel/machine_kexec.c

@@ -321,7 +321,7 @@ void crash_post_resume(void)
  * but does not hold any data of loaded kernel image.
  *
  * Note that all the pages in crash dump kernel memory have been initially
- * marked as Reserved in kexec_reserve_crashkres_pages().
+ * marked as Reserved as memory was allocated via memblock_reserve().
  *
  * In hibernation, the pages which are Reserved and yet "nosave" are excluded
  * from the hibernation iamge. crash_is_nosave() does thich check for crash