[Report] annoyed dma debug warning "cacheline tracking EEXIST, overlapping mappings aren't supported"

[Ming Lei]

Hello Guys,

I got more and more reports on DMA debug warning "cacheline tracking EEXIST,
overlapping mappings aren't supported" in storage related tests:

1) liburing
- test/iopoll-overflow.t
- test/sq-poll-dup.t

Same buffer is used in more than 1 IO.

2) raid1 driver

- same buffer is used in more than 1 bio

3) some storage utilities
- dm thin provisioning utility of thin_check
- `dt`(https://github.com/RobinTMiller/dt)

I looks like same user buffer is used in more than 1 dio.

4) some self cooked test code which does same thing with 1)

In storage stack, the buffer provider is far away from the actual DMA
controller operating code, which doesn't have the knowledge if
DMA_ATTR_SKIP_CPU_SYNC should be set.

And suggestions for avoiding this noise?

Thanks,
Ming