Re: [PATCH 1/1] scsi: storvsc: Fix swiotlb bounce buffer leak in confidential VM
From: Martin K. Petersen
Date: Tue Dec 13 2022 - 21:55:40 EST
Michael,
> storvsc_queuecommand() maps the scatter/gather list using scsi_dma_map(),
> which in a confidential VM allocates swiotlb bounce buffers. If the
> I/O submission fails in storvsc_do_io(), the I/O is typically retried
> by higher level code, but the bounce buffer memory is never freed.
> The mostly like cause of I/O submission failure is a full VMBus
> channel ring buffer, which is not uncommon under high I/O loads.
> Eventually enough bounce buffer memory leaks that the confidential
> VM can't do any I/O. The same problem can arise in a non-confidential
> VM with kernel boot parameter swiotlb=force.
Applied to 6.2/scsi-staging, thanks!
--
Martin K. Petersen Oracle Linux Engineering