GHC 8.2.1 segfaults while bootstrapping master

Earlier this week the Linux/amd64 Harbormaster started failing somewhat reliably during validation. It seems the stage0 compiler (GHC 8.2.1) often fails with a segmentation fault. This seems to have started with ef26182e although I suspect this isn't causal. I was able to capture a core dump of the crashing stage0 compiler which implicates the allocator,

Reading symbols from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/ghc...(no debugging symbols found)...done.
[New LWP 25151]
[New LWP 25160]
[New LWP 25156]
[New LWP 25158]
[New LWP 25157]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/opt/ghc/8.2.1/lib/ghc-8.2.1/bin/ghc -B/opt/ghc/8.2.1/lib/ghc-8.2.1 -hisuf hi -'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007f836aaa2c90 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
[Current thread is 1 (Thread 0x7f83711b5340 (LWP 25151))]
(gdb) bt
#0  0x00007f836aaa2c90 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#1  0x00007f836aaa3211 in allocGroupOnNode () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#2  0x00007f836aa9dd41 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#3  0x00007f836aa9deb9 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#4  0x00007f836aa82a39 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#5  0x00007f836aa7fc06 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#6  0x00007f836aa9d461 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#7  0x00007f836aaa423a in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#8  0x00007f836aaa4b3c in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#9  0x00007f836aa8bbc8 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#10 0x00007f836aa8c912 in ?? () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#11 0x00007f836aa8da01 in scheduleWaitThread () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#12 0x00007f836aa99fae in hs_main () from /opt/ghc/8.2.1/lib/ghc-8.2.1/bin/../rts/libHSrts_thr-ghc8.2.1.so
#13 0x0000000000427038 in ?? ()
#14 0x00007f83694fd2b1 in __libc_start_main (main=0x426fd0, argc=119, argv=0x7fffcfee8078, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffcfee8068) at ../csu/libc-start.c:291
#15 0x0000000000427069 in ?? ()

Trac metadata

Trac field	Value
Version	8.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	highest
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture