linux-kernel - Re: [PATCH AUTOSEL 4.14 18/37] nvme-pci: fix conflicting p2p resource adds

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Date:   Wed, 3 Apr 2019 08:57:30 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     "Heitke, Kenneth" <kenneth.heitke@...el.com>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Keith Busch <keith.busch@...el.com>,
        Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
        linux-nvme@...ts.infradead.org
Subject: Re: [PATCH AUTOSEL 4.14 18/37] nvme-pci: fix conflicting p2p
 resource adds

On Mon, Apr 01, 2019 at 11:37:52AM -0600, Heitke, Kenneth wrote:
>
>On 3/29/2019 7:30 PM, Sasha Levin wrote:
>>From: Keith Busch <keith.busch@...el.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@...el.com>
>>Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
>>Signed-off-by: Christoph Hellwig <hch@....de>
>>Signed-off-by: Jens Axboe <axboe@...nel.dk>
>>Signed-off-by: Sasha Levin <sashal@...nel.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 06355ca832db..ae03a5b70324 100644
>>--- a/drivers/nvme/host/pci.c
>>+++ b/drivers/nvme/host/pci.c
>>@@ -1546,6 +1546,9 @@ static void __iomem *nvme_map_cmb(struct nvme_dev *dev)
>>  	void __iomem *cmb;
>>  	int bar;
>>+	if (dev->cmb_size)
>>+		return;
>>+
>>  	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
>>  	if (!(NVME_CMB_SZ(dev->cmbsz)))
>>  		return NULL;
>>@@ -2034,7 +2037,6 @@ 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)) {
>>@@ -2434,6 +2436,7 @@ 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 4.14 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.

I've removed it, thanks!

--
Thanks,
Sasha