Heap allocation doesn't properly detect out of memory error

[robert-w-gries]

This problem comes up while testing scheduling.

On x86_64, we can create around 50 processes. If we then start a process cycle where each process creates the other, we hit a page fault and sometimes a double fault.

Error code: (empty)
ExceptionStack {
    instruction_pointer: 0x1116b6,
    code_segment: 0x8,
    cpu_flags: 0x6,
    stack_pointer: 0x40017940,
    stack_segment: 0x10
}
InterruptDescription {
    vector: 14,
    mnemonic: "#PF",
    description: "Page Fault",
    irqtype: "Fault",
    source: "Any memory reference."
}

Page fault while accessing 0x3fffffff

The instruction pointer points to a BTreeMap related function:

000000000013f130 <_ZN219_$LT$alloc..btree..node..Handle$LT$alloc..btree..node..NodeRef$LT$alloc..btree..node..marker..Mut$LT$$u27$a$GT$$C$$u20$K$C$$u20$V$C$$u20$alloc..btree..node..marker..Leaf$GT$$C$$u20$alloc..btree..node..marker..KV$GT$$GT$5split17h962bd6a453e19508E>:
  13f130:   55                      push   %rbp
  13f131:   48 89 e5                mov    %rsp,%rbp
  13f134:   48 81 ec a0 0f 00 00    sub    $0xfa0,%rsp
  13f13b:   48 89 f8                mov    %rdi,%rax
  13f13e:   48 8d 8d 60 f1 ff ff    lea    -0xea0(%rbp),%rcx
  13f145:   c6 85 56 f9 ff ff 00    movb   $0x0,-0x6aa(%rbp)
  13f14c:   c6 85 55 f9 ff ff 00    movb   $0x0,-0x6ab(%rbp)
  13f153:   c6 85 57 f9 ff ff 00    movb   $0x0,-0x6a9(%rbp)
  13f15a:   c6 85 54 f9 ff ff 00    movb   $0x0,-0x6ac(%rbp)
  13f161:   c6 85 53 f9 ff ff 00    movb   $0x0,-0x6ad(%rbp)
  13f168:   48 89 bd 50 f1 ff ff    mov    %rdi,-0xeb0(%rbp)
  13f16f:   48 89 cf                mov    %rcx,%rdi
  13f172:   48 89 85 48 f1 ff ff    mov    %rax,-0xeb8(%rbp)
  13f179:   48 89 b5 40 f1 ff ff    mov    %rsi,-0xec0(%rbp)
  13f180:   e8 1b 25 00 00          callq  1416a0 <_ZN55_$LT$alloc..btree..node..LeafNode$LT$K$C$$u20$V$GT$$GT$3new17h54747f5e44c2a0b4E>
  13f185:   eb 0e                   jmp    13f195 <_ZN219_$LT$alloc..btree..node..Handle$LT$alloc..btree..node..NodeRef$LT$alloc..btree..node..marker..Mut$LT$$u27$a$GT$$C$$u20$K$C$$u20$V$C$$u20$alloc..btree..node..marker..Leaf$GT$$C$$u20$alloc..btree..node..marker..KV$GT$$GT$5split17h962bd6a453e19508E+0x65>