I went and tested the released and -proposed versions of systemtap along
with the GA and HWE kernels on xenial. This is what I found:

Tests 1 and 2, confirming that current package is broken:

Test 1:
Xenial 4.4.0-165-generic kernel, Systemtap 2.9-2ubuntu2
Test results: 
https://paste.ubuntu.com/p/MhVhHJHkMT/
We failed to load the trivial hello world probe. As reported.

Test 2:
Xenial 4.15.0-66-generic #75~16.04.1-Ubuntu HWE kernel, Systemtap 2.9-2ubuntu2
Test results:
https://paste.ubuntu.com/p/pZYrpHNWCV/
We failed to load the trivial hello world probe. As reported.

Tests 3 and 4, with the new package in -proposed:

Test 3:
Xenial 4.4.0-165-generic #193-Ubuntu GA kernel, Systemtap 2.9-2ubuntu2.1 from 
-proposed.
Test results:
https://paste.ubuntu.com/p/SGC8wKdS6W/
We successfully loaded the trivial hello world probe. -proposed package fixes 
issue.

Test 4:
Xenial 4.15.0-66-generic #75~16.04.1-Ubuntu HWE kernel, Systemtap 
2.9-2ubuntu2.1 from -proposed.
Test results:
https://paste.ubuntu.com/p/PnzMknQxqP/
We failed to load the trivial hello world probe. HWE kernels are still broken.

While the package in -proposed does solve the problem for the GA 4.4
kernel, this package is still incompatible with the 4.15 HWE kernel, as
per Bug 1683876.

Another thing that is critical to mention, is that the function
signature change that happened because of "mm: replace get_user_pages()
write/force parameters with gup_flags" landed in xenial 4.4.0-143 #169
earlier this year.

That means if we release the systemtap 2.9-2ubuntu2.1 from -proposed,
which requires the above commit from 4.4.0-143 #169 onward, systemtap
will then break for all users of xenial 4.4.0-142 and previous, as
systemtap 2.9-2ubuntu2.1 would contain the wrong function signature.

This would cause regressions if users are using the updated systemtap
package with older kernels, but do not wish to upgrade their kernel.

Because of this, I will not mark this bug as verified, as this needs
more discussion before we go releasing this package.

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https://bugs.launchpad.net/bugs/1830226

Title:
  systemtap currently broken in xenial

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