POSIX osDecommitMemory has nasty compatibility problems

osDecommitMemory in rts/posix/OSMem.c currently does the following,

#ifdef MADV_FREE
    // Try MADV_FREE first, FreeBSD has both and MADV_DONTNEED
    // just swaps memory out
    r = madvise(at, size, MADV_FREE);
#else
    r = madvise(at, size, MADV_DONTNEED);
#endif
    if(r < 0)
        sysErrorBelch("unable to decommit memory");

As it turns out, the Linux kernel as of 4.5 supports MADV_FREE. This means that binary distributions built in such environments will use MADV_FREE, even if running on an older kernel that does not support this advice. Ultimately this means that any attempt to decommit will fail.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	simonmar
Operating system
Architecture