linux-kernel - [PATCH] genwqe: Fix size check

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Date:   Wed, 12 Dec 2018 14:45:18 +0100
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Frank Haverkamp <haver@...ux.vnet.ibm.com>
Cc:     "Guilherme G . Piccoli" <gpiccoli@...ux.vnet.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>
Subject: [PATCH] genwqe: Fix size check

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@...r.kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
---
 drivers/misc/genwqe/card_utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 3fcb9a2fe1c9..efe2fb72d54b 100644
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -215,7 +215,7 @@ u32 genwqe_crc32(u8 *buff, size_t len, u32 init)
 void *__genwqe_alloc_consistent(struct genwqe_dev *cd, size_t size,
 			       dma_addr_t *dma_handle)
 {
-	if (get_order(size) > MAX_ORDER)
+	if (get_order(size) >= MAX_ORDER)
 		return NULL;
 
 	return dma_zalloc_coherent(&cd->pci_dev->dev, size, dma_handle,
-- 
2.19.1