From 14572de82e5022899e5856008bc9cac97004a88c Mon Sep 17 00:00:00 2001 From: Hui Su Date: Tue, 18 Aug 2026 18:33:36 +0800 Subject: [PATCH] io_uring/waitid: honor task_work cancellation io_waitid_cb() may run through the fallback task_work path when task_work_add() can no longer queue work to the originating task. The fallback runs from a kworker and io_uring marks such task work as canceled through tw.cancel. io_waitid_cb() currently ignores tw.cancel and calls __do_wait(). waitid is task-context dependent: __do_wait() performs child lookup relative to current, and the retry path also uses current->signal->wait_chldexit. If the callback runs from the fallback kworker, current is therefore not the task that submitted the request. Honor tw.cancel before entering __do_wait(). Complete the request with -ECANCELED and skip the siginfo copy, since canceled task work may run without the submitting task's userspace execution context. Keep the existing siginfo handling for normal waitid completion and explicit cancellation. Fixes: f31ecf671ddc ("io_uring: add IORING_OP_WAITID support") Cc: stable@vger.kernel.org Signed-off-by: Hui Su Link: https://patch.msgid.link/20260818103336.1922818-2-sh_def@163.com Signed-off-by: Jens Axboe --- io_uring/waitid.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/io_uring/waitid.c b/io_uring/waitid.c index 76af129ba8ca..596f2da40260 100644 --- a/io_uring/waitid.c +++ b/io_uring/waitid.c @@ -125,7 +125,7 @@ static void io_waitid_remove_wq(struct io_kiocb *req) } } -static void io_waitid_complete(struct io_kiocb *req, int ret) +static void io_waitid_complete(struct io_kiocb *req, int ret, bool copy_si) { struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); @@ -137,7 +137,10 @@ static void io_waitid_complete(struct io_kiocb *req, int ret) hlist_del_init(&req->hash_node); io_waitid_remove_wq(req); - ret = io_waitid_finish(req, ret); + if (copy_si) + ret = io_waitid_finish(req, ret); + else + io_waitid_free(req); if (ret < 0) req_set_fail(req); io_req_set_res(req, ret, 0); @@ -159,7 +162,7 @@ static bool __io_waitid_cancel(struct io_kiocb *req) if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK) return false; - io_waitid_complete(req, -ECANCELED); + io_waitid_complete(req, -ECANCELED, true); io_req_queue_tw_complete(req, -ECANCELED); return true; } @@ -202,6 +205,11 @@ static void io_waitid_cb(struct io_tw_req tw_req, io_tw_token_t tw) int ret; io_tw_lock(ctx, tw); + if (unlikely(tw.cancel)) { + io_waitid_complete(req, -ECANCELED, false); + io_req_task_complete(tw_req, tw); + return; + } ret = __do_wait(&iwa->wo); @@ -229,7 +237,7 @@ static void io_waitid_cb(struct io_tw_req tw_req, io_tw_token_t tw) } } - io_waitid_complete(req, ret); + io_waitid_complete(req, ret, true); io_req_task_complete(tw_req, tw); }