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    SubjectRe: [PATCH 2/4] virtio-mem: Fix probe failed when modprobe virtio_mem
    On 28.11.22 03:10, Li Zetao wrote:
    > When doing the following test steps, an error was found:
    > step 1: modprobe virtio_mem succeeded
    > # modprobe virtio_mem <-- OK
    >
    > step 2: fault injection in virtio_mem_init()
    > # modprobe -r virtio_mem <-- OK
    > # ...
    > CPU: 0 PID: 1837 Comm: modprobe Not tainted
    > 6.1.0-rc6-00285-g6a1e40c4b995-dirty
    > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
    > Call Trace:
    > <TASK>
    > should_fail.cold+0x5/0x1f
    > ...
    > virtio_mem_init_hotplug+0x9ae/0xe57 [virtio_mem]
    > virtio_mem_init.cold+0x327/0x339 [virtio_mem]
    > virtio_mem_probe+0x48e/0x910 [virtio_mem]
    > virtio_dev_probe+0x608/0xae0
    > ...
    > </TASK>
    > virtio_mem virtio4: could not reserve device region
    > virtio_mem: probe of virtio4 failed with error -16
    >
    > step 3: modprobe virtio_net failed

    virtio_net ?

    > # modprobe virtio_mem <-- failed
    > virtio_mem: probe of virtio4 failed with error -16
    >
    > The root cause of the problem is that the virtqueues are not
    > stopped on the error handling path when virtio_mem_init()
    > fails in virtio_mem_probe(), resulting in an error "-ENOENT"
    > returned in the next modprobe call in setup_vq().
    >
    > virtio_pci_modern_device uses virtqueues to send or
    > receive message, and "queue_enable" records whether the
    > queues are available. In vp_modern_find_vqs(), all queues
    > will be selected and activated, but once queues are enabled
    > there is no way to go back except reset.
    >
    > Fix it by reset virtio device on error handling path. After
    > virtio_mem_init_vq() succeeded, all virtqueues should be
    > stopped on error handling path.
    >
    > Fixes: 1fcf0512c9c8 ("virtio_pci: modern driver")

    That commit is from 2014. virtio-mem was merged in 2020

    Fixes: 5f1f79bbc9e2 ("virtio-mem: Paravirtualized memory hotplug")

    > Signed-off-by: Li Zetao <lizetao1@huawei.com>
    > ---
    > drivers/virtio/virtio_mem.c | 1 +
    > 1 file changed, 1 insertion(+)
    >
    > diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
    > index 0c2892ec6817..c7f09c2ce982 100644
    > --- a/drivers/virtio/virtio_mem.c
    > +++ b/drivers/virtio/virtio_mem.c
    > @@ -2793,6 +2793,7 @@ static int virtio_mem_probe(struct virtio_device *vdev)
    >
    > return 0;
    > out_del_vq:
    > + virtio_reset_device(vdev);
    > vdev->config->del_vqs(vdev);
    > out_free_vm:
    > kfree(vm);


    Apart from that

    Reviewed-by: David Hildenbrand <david@redhat.com>

    --
    Thanks,

    David / dhildenb

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