Via bug 1560024 we're backporting the new system call MEMBARRIER(2), and as such its availability must be documented accordingly in the man pages.
# man 2 membarrier
MEMBARRIER(2) Linux Programmer's Manual MEMBARRIER(2)
membarrier - issue memory barriers on a set of threads
int membarrier(int cmd, int flags);
The membarrier() system call helps reducing the overhead of the memory barrier instructions required to order memory accesses on multi-core systems. However, this system call
is heavier than a memory barrier, so using it effectively is not as simple as replacing memory barriers with this system call, but requires understanding of the details below.
man-pages-overrides-7.5.2-1.el7 -- on RHEL-7.5-released
No output on man 2 membarrier present.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.