Ben Gamari authored Nov 01, 2015 and Ben Gamari committed Nov 01, 2015

Since the two-step allocator the RTS asks the kernel for a large upfront
mmap'd region of memory (on the order of terabytes). While we have no
expectation that this entire region will be backed by physical memory,
this scheme nevertheless fails on some systems with resource limits.
Here we use a back-off scheme to reduce our allocation request until we
find a size agreeable to the kernel. Fixes #10877.

This also fixes a latent bug wherein the heap reservation retry logic
would fail to free the previously reserved address space, which would
likely result in a heap allocation failure.

Test Plan:
set address space limit with `ulimit -v 67108864` and try running
a compiled program

Reviewers: simonmar, austin

Reviewed By: simonmar

Subscribers: thomie, RyanGlScott

Differential Revision: https://phabricator.haskell.org/D1405

GHC Trac Issues: #10877