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Date:   Wed, 12 Dec 2018 15:18:55 +0100
From:   haver <haver@linux.vnet.ibm.com>
To:     Christian Borntraeger <borntraeger@de.ibm.com>
Cc:     "Guilherme G . Piccoli" <gpiccoli@linux.vnet.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] genwqe: Fix size check
In-Reply-To: <20181212134518.4587-1-borntraeger@de.ibm.com>
References: <20181212134518.4587-1-borntraeger@de.ibm.com>
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Hi Christian,

On 2018-12-12 14:45, Christian Borntraeger wrote:
> 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>
> ---
>  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,

Thanks for sending a fix for this ugly message.
Regards

Frank

Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>