[RFC 0/2] io_uring: disallow overlapping ranges for buffer registration

[Bijan Mottahedeh <bijan.mottahedeh@oracle.com>]

This patch set has a couple of RFCs.

The first patch aims to disallow overlapping of user buffers for
registration.  For example, right now it is possible to register the same
identical buffer many times with the same system call which doesn't really
make sense.  I'm not sure if there is a valid use case for overlapping
buffers.  I think this check by itself might not be sufficient and more
restrictions may be needed but I figured to send this out for feedback and
check whether overlapping buffers should be allowed in the first place.

The second patch aims to separate reporting and enforcing of pinned
memory usage.  Reporting the usage seems like a good idea even if no
limit is enforced and ctx->account_mem is zero.

However, I'm clear on the proper setting and usage of
	user->locked_vm
	mm->locked_vm
	mm->pinned_vm

Looking at some other pin_user_page() callers, it seem mm->pinned_vm
should be used by I'm not sure.

Bijan Mottahedeh (2):
  io_uring: disallow overlapping ranges for buffer registration
  io_uring: report pinned memory usage

 fs/io_uring.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

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1.8.3.1