diff options
| author | Tao Cui <cuitao@kylinos.cn> | 2026-08-15 10:20:17 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-08-14 23:50:47 -1000 |
| commit | 8d8dd8ae89eaa78b37fc85528e926029f5facbdf (patch) | |
| tree | 1f02e419b17216e8e0d08c8e91eb6da7eb441bac | |
| parent | 56bbc91219c0711f1580a8ba7cd60471b6e1684e (diff) | |
sched_ext: Don't BUG_ON a destroyed DSQ in process_deferred_reenq_users
scx_bpf_dsq_reenq() queues a deferred reenq (dru) that runs from
run_deferred(), not ops.dispatch(). If the DSQ is destroyed before the dru
runs, process_deferred_reenq_users() sees dsq->id == SCX_DSQ_INVALID and
hits the BUG_ON. destroy_dsq() doesn't flush pending drus, so just skip.
tj: Read dsq->id once with READ_ONCE(). Reading it separately in the INVALID
check and the BUG_ON would leave a window where destroy_dsq() can
invalidate the id between the two reads and still trigger the BUG_ON.
Fixes: 84b1a0ea0b7c ("sched_ext: Implement scx_bpf_dsq_reenq() for user DSQs")
Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | kernel/sched/ext/ext.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 0b31a9976e97..950d98508463 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4613,7 +4613,7 @@ static void process_deferred_reenq_users(struct rq *rq) while (true) { struct scx_dispatch_q *dsq; - u64 reenq_flags; + u64 dsq_id, reenq_flags; scoped_guard (raw_spinlock, &rq->scx.deferred_reenq_lock) { struct scx_deferred_reenq_user *dru = @@ -4636,7 +4636,12 @@ static void process_deferred_reenq_users(struct rq *rq) /* see schedule_dsq_reenq() */ smp_mb(); - BUG_ON(dsq->id & SCX_DSQ_FLAG_BUILTIN); + /* destroy_dsq() may have raced and invalidated @dsq, nothing to reenq */ + dsq_id = READ_ONCE(dsq->id); + if (unlikely(dsq_id == SCX_DSQ_INVALID)) + continue; + + BUG_ON(dsq_id & SCX_DSQ_FLAG_BUILTIN); reenq_user(rq, dsq, reenq_flags); } } |