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Date:   Fri, 9 Nov 2018 08:49:55 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     John Stultz <john.stultz@linaro.org>
Cc:     hch@lst.de, Will Deacon <will.deacon@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        robin.murphy@arm.com, konrad.wilk@oracle.com,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        iommu@lists.linux-foundation.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Valentin Schneider <valentin.schneider@arm.com>
Subject: Re: [PATCH 06/10] swiotlb: use swiotlb_map_page in
 swiotlb_map_sg_attrs
Message-ID: <20181109074955.GA27489@lst.de>
References: <20181008080246.20543-1-hch@lst.de> <20181008080246.20543-7-hch@lst.de> <CANcMJZAzrxA9LGNvP-epv2DwsUacEM_hcgA1n5gmaPuWRJG4iw@mail.gmail.com>
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On Tue, Nov 06, 2018 at 05:27:14PM -0800, John Stultz wrote:
> But at that point if I just re-apply "swiotlb: use swiotlb_map_page in
> swiotlb_map_sg_attrs", I reproduce the hangs.
> 
> Any suggestions for how to further debug what might be going wrong
> would be appreciated!

Very odd.  In the end map_sg and map_page are defined to do the same
things to start with.  The only real issue we had in this area was:

"[PATCH v2] of/device: Really only set bus DMA mask when appropriate"

so with current mainline + that you still see a problem, and if you
rever the commit we are replying to it still goes away?