On Tue, Aug 16, 2016 at 05:19:31PM -0400, Chris Metcalf wrote:

In do_notify_resume(), call task_isolation_ready() for
TIF_TASK_ISOLATION tasks when we are checking the thread-info flags;
and after we've handled the other work, call task_isolation_enter()
for such tasks.  To ensure we always call task_isolation_enter() when
returning to userspace, add _TIF_TASK_ISOLATION to _TIF_WORK_MASK,
while leaving the old bitmask value as _TIF_WORK_LOOP_MASK to
check while looping.

We tweak syscall_trace_enter() slightly to carry the "flags"
value from current_thread_info()->flags for each of the tests,
rather than doing a volatile read from memory for each one.  This
avoids a small overhead for each test, and in particular avoids
that overhead for TIF_NOHZ when TASK_ISOLATION is not enabled.

We instrument the smp_send_reschedule() routine so that it checks for
isolated tasks and generates a suitable warning if we are about
to disturb one of them in strict or debug mode.

Finally, report on page faults in task-isolation processes in
do_page_faults().

Signed-off-by: Chris Metcalf <redacted>
---
 arch/arm64/Kconfig                   |  1 +
 arch/arm64/include/asm/thread_info.h |  5 ++++-
 arch/arm64/kernel/ptrace.c           | 18 +++++++++++++++---
 arch/arm64/kernel/signal.c           | 10 ++++++++++
 arch/arm64/kernel/smp.c              |  2 ++
 arch/arm64/mm/fault.c                |  8 +++++++-

Not sure when/how this series will be merged (Will already picked patch
07/13 as a general clean-up) but this arm64 patch:

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>