Commit 87019cb6 authored Apr 19, 2026 by Tejun Heo

sched_ext: Mark scx_sched_hash insecure_elasticity



scx_sched_hash is inserted into under scx_sched_lock (raw_spinlock_irq)
in scx_link_sched(). rhashtable's sync grow path calls get_random_u32()
and does a GFP_ATOMIC allocation; both acquire regular spinlocks, which
is unsafe under raw_spinlock_t. Set insecure_elasticity to skip the
sync grow.

v2:
- Dropped dsq_hash changes. Insertion is not under raw_spin_lock.

- Switched from no_sync_grow flag to insecure_elasticity.

Fixes: 25037af7 ("sched_ext: Add rhashtable lookup for sub-schedulers")
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 73bd1227

kernel/sched/ext.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -32,6 +32,7 @@ static const struct rhashtable_params scx_sched_hash_params = {
		.key_len = sizeof_field(struct scx_sched, ops.sub_cgroup_id),
		.key_offset = offsetof(struct scx_sched, ops.sub_cgroup_id),
		.head_offset = offsetof(struct scx_sched, hash_node),
		.insecure_elasticity = true, /* inserted under scx_sched_lock */
		};

		static struct rhashtable scx_sched_hash;