#15571: Eager AP_STACK blackholing causes incorrect size info for sanity checks -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.6.1 Component: Runtime System | Version: 8.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #15508 | Differential Rev(s): Phab:D5165 Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): I submitted a patch. Simon, looking at this note {{{ Note [zeroing slop] In some scenarios we write zero words into "slop"; memory that is left unoccupied after we overwrite a closure in the heap with a smaller closure. Zeroing slop is required for: - full-heap sanity checks (DEBUG, and +RTS -DS) - LDV profiling (PROFILING, and +RTS -hb) Zeroing slop must be disabled for: - THREADED_RTS with +RTS -N2 and greater, because we cannot overwrite slop when another thread might be reading it. Hence, slop is zeroed when either: - PROFILING && era <= 0 (LDV is on) - !THREADED_RTS && DEBUG And additionally: - LDV profiling and +RTS -N2 are incompatible - full-heap sanity checks are disabled for THREADED_RTS }}} This says that we can't zero slops in threaded runtime and heap sanity checks are disabled in threaded runtime, but that's not true. I can see in gdb that we do full heap sanity check in threaded programs too. Do you know what changed since this comment? I'm surprised that sanity checks work at all in threaded runtime because we don't zero the slops... -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15571#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler