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Mathieu Desnoyers authored
commit 90756533 upstream. Userspace applications should be allowed to expect the membarrier system call with MEMBARRIER_CMD_SHARED command to issue memory barriers on nohz_full CPUs, but synchronize_sched() does not take those into account. Given that we do not want unrelated processes to be able to affect real-time sensitive nohz_full CPUs, simply return ENOSYS when membarrier is invoked on a kernel with enabled nohz_full CPUs. Signed-off-by:
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Josh Triplett <josh@joshtriplett.org> CC: Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Rik van Riel <riel@redhat.com> Acked-by:
Lai Jiangshan <jiangshanlai@gmail.com> Reviewed-by:
Josh Triplett <josh@joshtriplett.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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