Fix bug in call_memory tracing when calling BIFs that delay GC #9706
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garazdawi
previously approved these changes
Apr 9, 2025
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erts/emulator/beam/erl_gc.c:578
- Ensure that updating p->high_water at this new location handles all code paths, including cases where p->abandoned_heap is true, so that the memory break adjustment is consistently applied.
p->high_water = p->heap;
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The call to erts_adjust_memory_break(, orig_htop - p->high_water) must use the old value of p->high_water. Otherwise the reported call_memory value may get arbitrarily wrong, even negative number of words.
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garazdawi
approved these changes
Apr 10, 2025
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Tracing functions with
call_memorycould report arbitrarily incorrect values for consumed memory. Even negative values. This could happen if the traced process called BIFs that yielded while delaying garbage collection, likebinary_to_list/1.