[PATCH v2 1/2] nvme-pci: release iomap and prp_pools in nvme_pci_free_ctrl

[keith.busch@linux.intel.com (Keith Busch)]

On Wed, Jul 11, 2018@09:38:34PM +0800, Weiping Zhang wrote:
> Keith Busch <keith.busch at linux.intel.com> ?2018?7?10??? ??10:46???
> >
> > I'm getting the following warning with this patch:
> >
> Hi Keith,
> 
> How to reproduce this problem, I cann't reproduce it (apply these two
> patch on 4.18.0-rc4) as following steps:
> 1. rmmod nvme
> 2. git am these 2 patchs
> 3. make modules SUBDIRS=drivers/nvme
> 4. insmod drivers/nvme/host/nvme.ko
> 5. fdisk /dev/nvme0n1 and create a partition
> 6. mkfs.ext4 /dev/nvme0n1p1
> 7. mount /dev/nvme0n1p1 /mnt
> 8. echo aaaaaa > /mnt/b.log

8.1: Hot remove /dev/nvme0

The reference counting is to ensure that resources needed to close a
a holder (the mount point, in your example) aren't released during
the 'remove'. We have to release the prp pools and the io memory before
returning from the driver's 'remove' because the pci driver is going
to release their dependencies.

Anyway, I think the right thing to do is reorder the allocations to
something more appropriate:

---
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index ba943f211687..ddd441b1516a 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2556,11 +2556,6 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	quirks |= check_vendor_combination_bug(pdev);
 
-	result = nvme_init_ctrl(&dev->ctrl, &pdev->dev, &nvme_pci_ctrl_ops,
-			quirks);
-	if (result)
-		goto release_pools;
-
 	/*
 	 * Double check that our mempool alloc size will cover the biggest
 	 * command we support.
@@ -2578,6 +2573,11 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto release_pools;
 	}
 
+	result = nvme_init_ctrl(&dev->ctrl, &pdev->dev, &nvme_pci_ctrl_ops,
+			quirks);
+	if (result)
+		goto release_mempool;
+
 	dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
 
 	nvme_get_ctrl(&dev->ctrl);
@@ -2585,6 +2585,8 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	return 0;
 
+ release_mempool:
+	mempool_destroy(dev->iod_mempool);
  release_pools:
 	nvme_release_prp_pools(dev);
  unmap:
--

> 9. umount /mnt