[4.18.7] DMAR: Allocating 2048-page iova for 0000:00:14.0 failed

[Johann Kieleich]

Hi,
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not sure if this is the place to ask.
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I'm getting a LOT of these messages:

[70679.212719] DMAR: Allocating 2048-page iova for 0000:00:14.0 failed
[70679.508107] DMAR: Allocating 2048-page iova for 0000:00:14.0 failed
[70679.779284] DMAR: Allocating 2048-page iova for 0000:00:14.0 failed

( 00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05) )
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This happens while writing random data to an USB drive (Seagate Backup Plus 6TB).
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# pv < /dev/urandom > /dev/usbdrive
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The drive is new and I like to overwrite drives as a burn-in test, also as a pre-encryption wipe.
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This runs fine for an hour or two (a hundred gigs), then speed drops by more than half,
'top' shows usb-storage process eating CPU, mouse pointer and keyboard get sluggish,
and then a while later, these console messages appear.
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So far the only thing that has helped get things back in order (for a while)
is to reboot the machine entirely.
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I've no idea where to even start tackling this problem.
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Any suggestions?
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Thank you