sched: fix __sched_setscheduler() vs load balancing race
__sched_setscheduler() may release rq->lock in pull_rt_task() as a task is
being changed rt -> fair class. load balancing may sneak in, move the task
behind __sched_setscheduler()'s back, which explodes in switched_to_fair()
when the passed but no longer valid rq is used. Tell can_migrate_task() to
say no if ->pi_lock is held.
@stable: Kernels that predate SCHED_DEADLINE can use this simple (and tested)
check in lieu of backport of the full 18 patch mainline treatment.
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
[bwh: Backported to 3.2:
- Adjust numbering in the comment
- Adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Willy Tarreau <w@1wt.eu>
1 file changed