When using SCX_KICK_WAIT I noticed that it lacks any deadlock prevention and will deadlock with no chance of sched_ext even ejecting the BPF scheduler. The BPF scheduler cannot impose any reasonablesynchronisation itself, except for a strict partition of which CPUs are allowed to SCX_KICK_WAIT which other CPUs. Since SCX_KICK_WAIT seems to be used quite rarely, just synchronize all SCX_KICK_WAIT globally and don't try to be clever about cycle detection. Also add a testcase that reproduces the issue.
Christian Loehle (2): sched_ext: Prevent SCX_KICK_WAIT deadlock by serialization sched_ext/selftests: Add SCX_KICK_WAIT cycle tests kernel/sched/ext.c | 45 +++- tools/testing/selftests/sched_ext/Makefile | 1 + .../selftests/sched_ext/wait_kick_cycle.bpf.c | 70 ++++++ .../selftests/sched_ext/wait_kick_cycle.c | 223 ++++++++++++++++++ 4 files changed, 337 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/sched_ext/wait_kick_cycle.bpf.c create mode 100644 tools/testing/selftests/sched_ext/wait_kick_cycle.c -- 2.34.1
