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Date:   Thu, 27 Jun 2019 10:25:13 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Damien Le Moal <Damien.LeMoal@wdc.com>
Cc:     Ming Lei <ming.lei@redhat.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH V4 1/3] block: Allow mapping of vmalloc-ed buffers
Message-ID: <20190627082513.GA11043@lst.de>
References: <20190627024910.23987-1-damien.lemoal@wdc.com> <20190627024910.23987-2-damien.lemoal@wdc.com> <20190627074720.GB24671@ming.t460p> <BYAPR04MB581604217983C81B2BA5BA4FE7FD0@BYAPR04MB5816.namprd04.prod.outlook.com>
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On Thu, Jun 27, 2019 at 08:17:08AM +0000, Damien Le Moal wrote:
> > Are your sure that invalidate[|flush]_kernel_vmap_range is needed for
> > bio_copy_kernel? The vmalloc buffer isn't involved in IO, and only
> > accessed by CPU.
> 
> Not sure at all. I am a little out of my league here.
> Christoph mentioned that this is necessary.
> 
> Christoph, can you confirm ?

Ming is right.  Sorry for misleading you.