BugLink: https://bugs.launchpad.net/bugs/1811647

commit fdd66968 upstream.

Calling the test program genwqe_cksum with the default buffer size of
2MB triggers the following kernel warning on s390:

WARNING: CPU: 30 PID: 9311 at mm/page_alloc.c:3189 __alloc_pages_nodemask+0x45c/0xbe0
CPU: 30 PID: 9311 Comm: genwqe_cksum Kdump: loaded Not tainted 3.10.0-957.el7.s390x #1
task: 00000005e5d13980 ti: 00000005e7c6c000 task.ti: 00000005e7c6c000
Krnl PSW : 0704c00180000000 00000000002780ac (__alloc_pages_nodemask+0x45c/0xbe0)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3
Krnl GPRS: 00000000002932b8 0000000000b73d7c 0000000000000010 0000000000000009
           0000000000000041 00000005e7c6f9b8 0000000000000001 00000000000080d0
           0000000000000000 0000000000b70500 0000000000000001 0000000000000000
           0000000000b70528 00000000007682c0 0000000000277df2 00000005e7c6f9a0
Krnl Code: 000000000027809e: de7195001000	ed	1280(114,%r9),0(%r1)
	   00000000002780a4: a774fead		brc	7,277dfe
	  #00000000002780a8: a7f40001		brc	15,2780aa
	  >00000000002780ac: 92011000		mvi	0(%r1),1
	   00000000002780b0: a7f4fea7		brc	15,277dfe
	   00000000002780b4: 9101c6b6		tm	1718(%r12),1
	   00000000002780b8: a784ff3a		brc	8,277f2c
	   00000000002780bc: a7f4fe2e		brc	15,277d18
Call Trace:
([<0000000000277df2>] __alloc_pages_nodemask+0x1a2/0xbe0)
 [<000000000013afae>] s390_dma_alloc+0xfe/0x310
 [<000003ff8065f362>] __genwqe_alloc_consistent+0xfa/0x148 [genwqe_card]
 [<000003ff80658f7a>] genwqe_mmap+0xca/0x248 [genwqe_card]
 [<00000000002b2712>] mmap_region+0x4e2/0x778
 [<00000000002b2c54>] do_mmap+0x2ac/0x3e0
 [<0000000000292d7e>] vm_mmap_pgoff+0xd6/0x118
 [<00000000002b081c>] SyS_mmap_pgoff+0xdc/0x268
 [<00000000002b0a34>] SyS_old_mmap+0x8c/0xb0
 [<000000000074e518>] sysc_tracego+0x14/0x1e
 [<000003ffacf87dc6>] 0x3ffacf87dc6

turns out the check in __genwqe_alloc_consistent uses "> MAX_ORDER"
while the mm code uses ">= MAX_ORDER". Fix genwqe.

Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>