From fdfce905a58edea053ee7b68b5bd4348dd1b36e0 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 15 Oct 2026 14:18:22 -0600 Subject: [PATCH] io_uring/timeout: don't put a sequence target behind the last flush io_timeout_fn() and io_kill_timeout() bump ->cq_timeouts when a timeout fires, but its CQE is only posted later from task_work. Until then the sequence io_timeout() computes is one below the last flush per fired timeout. Now that ->cq_last_tm_flush is kept while sequence timeouts are pending, a timeout armed in that window with a small offset gets a target behind the base. Its distance from the base wraps, and it's never completed by events, only by its timer. With DEFER_TASKRUN that window is as wide as the application makes it, as submission runs before the local task_work. Nothing but those in flight CQEs separates the two, so use the last flush as the base for the target when the sequence is behind it. Fixes: c6c0b3eba88c ("io_uring/timeout: don't skip over reached sequences") Signed-off-by: Jens Axboe --- io_uring/timeout.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/io_uring/timeout.c b/io_uring/timeout.c index b219dfdf7af5..e52ba4ad53cb 100644 --- a/io_uring/timeout.c +++ b/io_uring/timeout.c @@ -690,7 +690,6 @@ int io_timeout(struct io_kiocb *req, unsigned int issue_flags) } tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts); - timeout->target_seq = tail + off; /* * Update the last seq here in case io_flush_timeouts() hasn't, it only @@ -704,6 +703,15 @@ int io_timeout(struct io_kiocb *req, unsigned int issue_flags) ctx->cq_last_tm_flush = tail; base = ctx->cq_last_tm_flush; + /* + * A fired timeout bumps ->cq_timeouts before its CQE is posted, which + * leaves the sequence behind the last flush until it is. Nothing else + * separates the two then, so count from the flush. + */ + if ((s32)(tail - base) < 0) + tail = base; + timeout->target_seq = tail + off; + /* * Insertion sort, ensuring the first entry in the list is always * the one we need first.