Test dlopen fails since c7d57227

[bernhardu]

Did a test run with current git with a regular x86_64 build and found test dlopen failing in replaying step.
A bisect leads to c7d5722 as first broken commit.
When recording with -n the replay succeeds.
This happens with a "AMD Ryzen 7 1700", no VM, zen kernel module workaround.

(rr) reverse-continue
Continuing.
[FATAL src/ReplaySession.cc:1315:[dlopen_apply_mprotect_records.txt](https://github.com/rr-debugger/rr/files/13809186/dlopen_apply_mprotect_records.txt)()] 
 (task 3086426 (rec:3086392) at time 227)
 -> Assertion `r.start == recorded_r.start && r.size == recorded_r.size && r.prot == recorded_r.prot' failed to hold. Trace mprotect records don't match the mprotect records generated by execution

dlopen_apply_mprotect_records.txt

[rocallahan]

Can you rerun with 12398d3 ?
I assume this doesn't happen with rr replay -a?

[bernhardu]

Thanks for having a look, rr replay -a works without issue.
The issue just shows up in reverse execution:

[FATAL src/ReplaySession.cc:1322:apply_mprotect_records()] 
 (task 3320325 (rec:3320256) at time 227)
 -> Assertion `r.start == recorded_r.start && r.size == recorded_r.size && r.prot == recorded_r.prot' failed to hold. Mismatched mprotect record 5: recorded 0x7ff1413d0000,0x1000,r--, got 0,0,---

Attached file shows the steps of the test done manually, with 12398d3.
dlopen_apply_mprotect_records_5.7.0-124-g12398d35.txt

[rocallahan]

Seems like a problem that mprotect_record_count_completed is 6 but the last record in the syscallbuf has not been written.

[rocallahan]

OK I found a way to reproduce this or something like it.

[bernhardu]

Thanks, with this I cannot see the issue with the dlopen test any longer.