UPSTREAM: sched/eas: Don't update misfit status if the task is pinned

If the task is pinned to a cpu, setting the misfit status means that
we'll unnecessarily continuously attempt to migrate the task but fail.

This continuous failure will cause the balance_interval to increase to
a high value, and eventually cause unnecessary significant delays in
balancing the system when real imbalance happens.

Caught while testing uclamp where rt-app calibration loop was pinned to
cpu 0, shortly after which we spawn another task with high util_clamp
value. The task was failing to migrate after over 40ms of runtime due to
balance_interval unnecessary expanded to a very high value from the
calibration loop.

Not done here, but it could be useful to extend the check for pinning to
verify that the affinity of the task has a cpu that fits. We could end
up in a similar situation otherwise.

Fixes: 3b1baa6496e6 ("sched/fair: Add 'group_misfit_task' load-balance type")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Acked-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210119120755.2425264-1-qais.yousef@arm.com


(cherry picked from commit 0ae78eec8aa64e645866e75005162603a77a0f49)

BUG=None (see commit c0d53bb091bb)
TEST=None

Signed-off-by: Linux Patches Robot <linux-patches-robot@chromeos-missing-patches.google.com.iam.gserviceaccount.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Change-Id: Ia6b8f829ce801df1b9caf4275b8ffba60c65ffc0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2719125


Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: minaripenguin <minaripenguin@users.noreply.github.com>