[DTrace-devel] [PATCH v2] dtprobed: use /proc/$pid/map_files, not the filename of the mapping

[Nick Alcock]

On 12 Feb 2026, Eugene Loh outgrape:

> I do not know what went wrong here.  I would have bet big money that I
> tested this, but here is what I find now with this patch:

So did I!

> test/unittest/usdt/tst.enabled.sh: Running timeout --signal=TERM 41 test/unittest/usdt/tst.enabled.sh /home/.../build/dtrace
> FAIL: expected results differ.
> 400000-401000:main:go
>
> Diff against expected:
> --- test/unittest/usdt/tst.enabled.r    2026-02-12 05:31:24.000000000 +0000
> +++ /tmp/runtest.6196/test.out  2026-02-12 18:09:58.980466976 +0000
> @@ -1,2 +1,2 @@
> -test:main:go
> +400000-401000:main:go

This suggests that symbol lookup is failing, which it shouldn't be,
because that *too* uses /proc/$pid/map_files, or should.

I clearly need to debug this. Got a system on which it goes wrong?