[PATCH 6.18 02/49] io_uring: allow io-wq workers to exit when unused

Greg Kroah-Hartman
2026-02-13T13:52:17Z

From: Li Chen <me@linux.beauty>

commit 91214661489467f8452d34edbf257488d85176e4 upstream.

io_uring keeps a per-task io-wq around, even when the task no longer has
any io_uring instances.

If the task previously used io_uring for file I/O, this can leave an
unrelated iou-wrk-* worker thread behind after the last io_uring
instance is gone.

When the last io_uring ctx is removed from the task context, mark the
io-wq exit-on-idle so workers can go away. Clear the flag on subsequent
io_uring usage.

Signed-off-by: Li Chen <me@linux.beauty>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
io_uring/tctx.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/io_uring/tctx.c
+++ b/io_uring/tctx.c
@@ -122,6 +122,14 @@ int __io_uring_add_tctx_node(struct io_r
return ret;
}
}
+
+ /*
+ * Re-activate io-wq keepalive on any new io_uring usage. The wq may have
+ * been marked for idle-exit when the task temporarily had no active
+ * io_uring instances.
+ */
+ if (tctx->io_wq)
+ io_wq_set_exit_on_idle(tctx->io_wq, false);
if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
node = kmalloc(sizeof(*node), GFP_KERNEL);
if (!node)
@@ -183,6 +191,9 @@ __cold void io_uring_del_tctx_node(unsig
if (tctx->last == node->ctx)
tctx->last = NULL;
kfree(node);
+
+ if (xa_empty(&tctx->xa) && tctx->io_wq)
+ io_wq_set_exit_on_idle(tctx->io_wq, true);
}

__cold void io_uring_clean_tctx(struct io_uring_task *tctx)