The following bug related to the Haskell runtime was reported in Launchpad:

Haskell's default behaviour of using large-address-space is causing pandoc to stuck in an infinite loop on QEMU 10 Edit
https://bugs.launchpad.net/ubuntu/+source/ghc/+bug/2111581

The problem seems to relate to the following loop in osReserveHeapMemory():

https://gitlab.haskell.org/ghc/ghc/-/blob/master/rts/posix/OSMem.c?ref_type=heads#L589

According to the mmap() manpage the address passed to the kernel in only a hint there is no guarantee that the same address will be used for allocation.

As shown in the strace logs attached in Launchpad this code can lead to an endless loop when the kernel decides always to return an address below 8 GiB.

It might make sense to round up the address to 8 GiB if the returned address is below 8 GiB and reduce *len accordingly instead of retrying.

Best regards

Heinrich

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