From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@lst.de>
Cc: Sebastian Ott <sebott@linux.ibm.com>,
Sagi Grimberg <sagi@grimberg.me>,
Max Gurtovoy <maxg@mellanox.com>,
Bart Van Assche <bvanassche@acm.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Alan Stern <stern@rowland.harvard.edu>,
Oliver Neukum <oneukum@suse.com>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-mmc@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-scsi@vger.kernel.org, megaraidlinux.pdl@broadcom.com,
MPT-FusionLinux.pdl@broadcom.com, linux-hyperv@vger.kernel.org,
linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net,
linux-kernel@vger.kernel.org
Subject: Re: properly communicate queue limits to the DMA layer
Date: Wed, 5 Jun 2019 13:17:15 -0600 [thread overview]
Message-ID: <591cfa1e-fecb-7d00-c855-3b9eb8eb8a2a@kernel.dk> (raw)
In-Reply-To: <20190605190836.32354-1-hch@lst.de>
On 6/5/19 1:08 PM, Christoph Hellwig wrote:
> Hi Jens,
>
> we've always had a bit of a problem communicating the block layer
> queue limits to the DMA layer, which needs to respect them when
> an IOMMU that could merge segments is used. Unfortunately most
> drivers don't get this right. Oddly enough we've been mostly
> getting away with it, although lately dma-debug has been catching
> a few of those issues.
>
> The segment merging fix for devices with PRP-like structures seems
> to have escalated this a bit. The first patch fixes the actual
> report from Sebastian, while the rest fix every drivers that appears
> to have the problem based on a code audit looking for drivers using
> blk_queue_max_segment_size, blk_queue_segment_boundary or
> blk_queue_virt_boundary and calling dma_map_sg eventually. Note
> that for SCSI drivers I've taken the blk_queue_virt_boundary setting
> to the SCSI core, similar to how we did it for the other two settings
> a while ago. This also deals with the fact that the DMA layer
> settings are on a per-device granularity, so the per-device settings
> in a few SCSI drivers can't actually work in an IOMMU environment.
>
> It would be nice to eventually pass these limits as arguments to
> dma_map_sg, but that is a far too big series for the 5.2 merge
> window.
Since I'm heading out shortly and since I think this should make
the next -rc, I'll tentatively queue this up.
--
Jens Axboe
next prev parent reply other threads:[~2019-06-05 19:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 19:08 properly communicate queue limits to the DMA layer Christoph Hellwig
2019-06-05 19:08 ` [PATCH 01/13] nvme-pci: don't limit DMA segement size Christoph Hellwig
2019-06-05 19:08 ` [PATCH 02/13] rsxx: don't call dma_set_max_seg_size Christoph Hellwig
2019-06-05 19:08 ` [PATCH 03/13] mtip32xx: also set max_segment_size in the device Christoph Hellwig
2019-06-05 19:08 ` [PATCH 04/13] mmc: " Christoph Hellwig
2019-06-05 19:08 ` [PATCH 05/13] scsi: add a host / host template field for the virt boundary Christoph Hellwig
2019-06-05 19:08 ` [PATCH 06/13] ufshcd: set max_segment_size in the scsi host template Christoph Hellwig
2019-06-05 19:08 ` [PATCH 07/13] storvsc: set virt_boundary_mask " Christoph Hellwig
2019-06-05 19:08 ` [PATCH 08/13] IB/iser: set virt_boundary_mask in the scsi host Christoph Hellwig
2019-06-05 20:22 ` Jason Gunthorpe
2019-06-05 23:35 ` Sagi Grimberg
2019-06-06 6:24 ` Christoph Hellwig
2019-06-06 12:59 ` Jason Gunthorpe
2019-06-06 14:19 ` Christoph Hellwig
2019-06-05 19:08 ` [PATCH 09/13] IB/srp: " Christoph Hellwig
2019-06-05 19:08 ` [PATCH 10/13] megaraid_sas: " Christoph Hellwig
2019-06-06 6:02 ` Hannes Reinecke
2019-06-06 6:41 ` Christoph Hellwig
2019-06-06 15:37 ` Kashyap Desai
2019-06-08 8:14 ` Christoph Hellwig
2019-06-13 19:58 ` Kashyap Desai
2019-06-17 8:44 ` Christoph Hellwig
2019-06-17 9:10 ` Kashyap Desai
2019-06-13 8:44 ` Christoph Hellwig
2019-06-13 20:04 ` Kashyap Desai
2019-06-05 19:08 ` [PATCH 11/13] mpt3sas: " Christoph Hellwig
2019-06-05 19:08 ` [PATCH 12/13] usb-storage: " Christoph Hellwig
2019-06-05 19:08 ` [PATCH 13/13] uas: " Christoph Hellwig
2019-06-05 19:17 ` Jens Axboe [this message]
2019-06-05 19:24 ` properly communicate queue limits to the DMA layer Christoph Hellwig
2019-06-07 5:52 ` Jens Axboe
2019-06-07 17:30 ` Martin K. Petersen
2019-06-08 8:10 ` Jens Axboe
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