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Alan Stern authored
usb-storage: Revert commit 747668db ("usb-storage: Set virt_boundary_mask to avoid SG overflows") Commit 747668db ("usb-storage: Set virt_boundary_mask to avoid SG overflows") attempted to solve a problem involving scatter-gather I/O and USB/IP by setting the virt_boundary_mask for mass-storage devices. However, it now turns out that this interacts badly with commit 09324d32 ("block: force an unlimited segment size on queues with a virt boundary"), which was added later. A typical error message is: ehci-pci 0000:00:13.2: swiotlb buffer is full (sz: 327680 bytes), total 32768 (slots), used 97 (slots) There is no longer any reason to keep the virt_boundary_mask setting for usb-storage. It was needed in the first place only for handling devices with a block size smaller than the maxpacket size and where the host controller was not capable of fully general scatter-gather operation (that is, able to merge two SG segments into a single USB packet). But: High-speed or slower connections never use a bulk maxpacket value larger than 512; The SCSI layer does not handle block devices with a block size smaller than 512 bytes; All the host controllers capable of SuperSpeed operation can handle fully general SG; Since commit ea44d190 ("usbip: Implement SG support to vhci-hcd and stub driver") was merged, the USB/IP driver can also handle SG. Therefore all supported device/controller combinations should be okay with no need for any special virt_boundary_mask. So in order to fix the swiotlb problem, this patch reverts commit 747668db. Reported-and-tested-by: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de> Link: https://marc.info/?l=linux-usb&m=157134199501202&w=2Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Seth Bollinger <Seth.Bollinger@digi.com> CC: <stable@vger.kernel.org> Fixes: 747668db ("usb-storage: Set virt_boundary_mask to avoid SG overflows") Acked-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1910211145520.1673-100000@iolanthe.rowland.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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