Re: [PATCH AUTOSEL 4.19 28/57] nvme-pci: fix conflicting p2p resource adds

Heitke, Kenneth
2019-04-01T17:37:40Z

On 3/29/2019 7:28 PM, Sasha Levin wrote:
> From: Keith Busch <keith.busch@intel.com>
>
> [ Upstream commit 9fe5c59ff6a1e5e26a39b75489a1420e7eaaf0b1 ]
>
> The nvme pci driver had been adding its CMB resource to the P2P DMA
> subsystem everytime on on a controller reset. This results in the
> following warning:
>
> ------------[ cut here ]------------
> nvme 0000:00:03.0: Conflicting mapping in same section
> WARNING: CPU: 7 PID: 81 at kernel/memremap.c:155 devm_memremap_pages+0xa6/0x380
> ...
> Call Trace:
> pci_p2pdma_add_resource+0x153/0x370
> nvme_reset_work+0x28c/0x17b1 [nvme]
> ? add_timer+0x107/0x1e0
> ? dequeue_entity+0x81/0x660
> ? dequeue_entity+0x3b0/0x660
> ? pick_next_task_fair+0xaf/0x610
> ? __switch_to+0xbc/0x410
> process_one_work+0x1cf/0x350
> worker_thread+0x215/0x3d0
> ? process_one_work+0x350/0x350
> kthread+0x107/0x120
> ? kthread_park+0x80/0x80
> ret_from_fork+0x1f/0x30
> ---[ end trace f7ea76ac6ee72727 ]---
> nvme nvme0: failed to register the CMB
>
> This patch fixes this by registering the CMB with P2P only once.
>
> Signed-off-by: Keith Busch <keith.busch@intel.com>
> Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/nvme/host/pci.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 7b9ef8e734e7..dca87cb485e9 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1649,6 +1649,9 @@ static void nvme_map_cmb(struct nvme_dev *dev)
> struct pci_dev *pdev = to_pci_dev(dev->dev);
> int bar;
>
> + if (dev->cmb_size)
> + return;
> +
> dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
> if (!dev->cmbsz)
> return;
> @@ -2133,7 +2136,6 @@ static void nvme_pci_disable(struct nvme_dev *dev)
> {
> struct pci_dev *pdev = to_pci_dev(dev->dev);
>
> - nvme_release_cmb(dev);
> pci_free_irq_vectors(pdev);
>
> if (pci_is_enabled(pdev)) {
> @@ -2585,6 +2587,7 @@ static void nvme_remove(struct pci_dev *pdev)
> nvme_stop_ctrl(&dev->ctrl);
> nvme_remove_namespaces(&dev->ctrl);
> nvme_dev_disable(dev, true);
> + nvme_release_cmb(dev);
> nvme_free_host_mem(dev);
> nvme_dev_remove_admin(dev);
> nvme_free_queues(dev, 0);

There is no P2P support in the 4.19 kernel so I'm not sure this change
is necessary. I would also worry that it might break things if the BARs
need to be remapped after a controller reset.
>