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Date: Tue, 12 Apr 2016 17:06:59 -0500
From: Andy Gross <andy.gross@linaro.org>
To: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
        Vinod Koul <vinod.koul@intel.com>, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        devicetree@vger.kernel.org, dmaengine@vger.kernel.org,
        Archit Taneja <architt@codeaurora.org>,
        Sinan Kaya <okaya@codeaurora.org>,
        Pramod Gurav <gpramod@codeaurora.org>
Subject: Re: [PATCH v3 1/6] dmaengine: qcom: bam_dma: fix dma free memory on
 remove
Message-ID: <20160412220659.GB24737@hector.attlocal.net>
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On Mon, Apr 11, 2016 at 11:38:38AM +0300, Stanimir Varbanov wrote:
> Building the driver as a module and when removing the already
> inserted module gives below:
> 
> [ 1389.392788] Unable to handle kernel paging request at virtual address ffffffbdc000001c
> [ 1389.421321] pgd = ffffffc02fa87000
> [ 1389.447899] [ffffffbdc000001c] *pgd=0000000000000000, *pud=0000000000000000
> [ 1389.460142] Internal error: Oops: 96000006 [#1] PREEMPT SMP
> [ 1389.466963] Modules linked in: qcom_bam_dma(-)
> [ 1389.486608] CPU: 2 PID: 2442 Comm: rmmod Not tainted 4.2.0+ #407
> [ 1389.493885] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
> [ 1389.501196] task: ffffffc035bae2c0 ti: ffffffc0368a8000 task.ti: ffffffc0368a8000
> [ 1389.508566] PC is at __free_pages+0xc/0x40
> [ 1389.515893] LR is at free_pages.part.93+0x30/0x38
> [ 1389.523141] pc : [<ffffffc00016180c>] lr : [<ffffffc00016197c>] pstate: 80000145
> [ 1389.530602] sp : ffffffc0368abc20
> [ 1389.537931] x29: ffffffc0368abc20 x28: ffffffc0368a8000
> [ 1389.549153] x27: 0000000000000000 x26: 0000000000000000
> [ 1389.560412] x25: ffffffc000cb2000 x24: 0000000000000170
> [ 1389.571530] x23: 0000000000000004 x22: ffffffc036bc5010
> [ 1389.582721] x21: ffffffc036bc5010 x20: 0000000000000000
> [ 1389.593981] x19: 0000000000000002 x18: 0000007fcbc8e8b0
> [ 1389.605301] x17: 0000007f9b8226ec x16: ffffffc0002089e8
> [ 1389.616647] x15: 0000007f9b8a0588 x14: 0ffffffffffffffc
> [ 1389.628039] x13: 0000000000000030 x12: 0000000000000000
> [ 1389.639436] x11: 0000000000000008 x10: ffffffc000ecc000
> [ 1389.650872] x9 : ffffffc035bae2c0 x8 : ffffffc035bae9a8
> [ 1389.662367] x7 : ffffffc035bae9a0 x6 : 0000000000000000
> [ 1389.673906] x5 : ffffffbdc000001c x4 : 0000000080000000
> [ 1389.685475] x3 : ffffffbdc0000000 x2 : 0000004080000000
> [ 1389.697049] x1 : 0000000000000003 x0 : ffffffbdc0000000
> 
> The memory has been already freed by bam_free_chan() so fix this
> by skiping already freed memory.
> 
> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>

Reviewed-by: Andy Gross <andy.gross@linaro.org>