STR: - On Linux, build using m-c cset ad16863d1d45 (tip as of right now) - Run |xvfb-run ./mach talos-test --e10s -a tart --spsProfile| to profile a tart run with e10s Expected: - tart runs and gets profiled Actual: - firefox crashes, see attached backtrace So far I'm able to reproduce this pretty consistently

Note that if I run this without --spsProfile it runs just fine, which is why I'm filing it under the profiler component. The backtrace also seems to implicate the profiler.

It looks like aSample->context is 0x0 in doNativeBacktrace, so the |mc| pointer is 0x28 and dereferencing it crashes.

This gets me past the crash

I just saw this bug. We probably want something similar to your work around but in doNativeBacktrace. It would be nice to know why we can't retrieve a context but the work around will still give us pseudostack data so it's perfectly acceptable if it's placed in doNativeBacktrace.