#7747: debug_p RTS is buggy (debugging and profiled)
-----------------------------+----------------------------------------------
Reporter: ezyang | Owner: ezyang
Type: bug | Status: new
Priority: normal | Component: Profiling
Version: 7.7 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Runtime crash | Blockedby:
Blocking: | Related:
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I think some of the sanity assertions that debugging enables are not being
adjusted adequately when profiling is turned on. We probably never caught
this because we don't build debug_p by default. I see some worse problems
under some more complicated test-cases but lets go with the simple case
first!
{{{
fib :: Integer -> Integer
fib 0 = 1
fib 1 = 1
fib n = fib (n-1) + fib (n-2)
main = print (fib 25)
}}}
built as
{{{
/srv/code/ghc-build-tick/inplace/bin/ghc-stage2 -fforce-recomp -fprof-drop
-prof -debug --make dp.hs -O -rtsopts
}}}
run as
{{{
ezyang@javelin:~/Dev/haskell$ ./dp +RTS -DS
cap 0: initialised
dp: internal error: checkClosure: found EVACUATED closure 0
(GHC version 7.7 for x86_64_unknown_linux)
Please report this as a GHC bug:
http://www.haskell.org/ghc/reportabug
Aborted (core dumped)
}}}
Here is the GDB backtrace:
{{{
Program received signal SIGABRT, Aborted.
0x00007ffff6ec4425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0 0x00007ffff6ec4425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007ffff6ec7b8b in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x0000000000a552b7 in rtsFatalInternalErrorFn (s=0xba5038
"checkClosure: found EVACUATED closure %d", ap=0x7fffffffd4d8) at
rts/RtsMessages.c:170
#3 0x0000000000a54eef in barf (s=0xba5038 "checkClosure: found EVACUATED
closure %d") at rts/RtsMessages.c:42
#4 0x0000000000a6a368 in checkClosure (p=0x7ffff64fe988) at
rts/sm/Sanity.c:237
#5 0x0000000000a6aa54 in checkHeapChain (bd=0x7ffff6403f80) at
rts/sm/Sanity.c:450
#6 0x0000000000a6b2f1 in checkGeneration (gen=0xe7a0e0,
after_major_gc=rtsFalse) at rts/sm/Sanity.c:706
#7 0x0000000000a6b3bc in checkFullHeap (after_major_gc=rtsFalse) at
rts/sm/Sanity.c:724
#8 0x0000000000a6b42b in checkSanity (after_gc=rtsFalse,
major_gc=rtsFalse) at rts/sm/Sanity.c:733
#9 0x0000000000a662bb in GarbageCollect (collect_gen=0,
do_heap_census=rtsFalse, gc_type=0, cap=0xe6b680 <MainCapability>) at
rts/sm/GC.c:298
#10 0x0000000000a579dd in scheduleDoGC (pcap=0x7fffffffd860,
task=0xe8ccf0, force_major=rtsFalse) at rts/Schedule.c:1651
#11 0x0000000000a56f92 in schedule (initialCapability=0xe6b680
<MainCapability>, task=0xe8ccf0) at rts/Schedule.c:553
#12 0x0000000000a582b6 in scheduleWaitThread (tso=0x7ffff6405378, ret=0x0,
pcap=0x7fffffffd930) at rts/Schedule.c:2359
#13 0x0000000000a98156 in rts_evalLazyIO (cap=0x7fffffffd930, p=0xdc2840,
ret=0x0) at rts/RtsAPI.c:497
#14 0x0000000000a54d5b in real_main () at rts/RtsMain.c:63
#15 0x0000000000a54e4a in hs_main (argc=3, argv=0x7fffffffda98,
main_closure=0xdc2840, rts_config=...) at rts/RtsMain.c:114
#16 0x0000000000404bb3 in main ()
}}}
and here is the heap in the vicinity of the problem:
{{{
(gdb) pmem (0x7ffff64fe988-16) 16
0x7ffff64fe9f0: 0x9d51c0