From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 531D27474 for ; Tue, 10 Jan 2023 18:21:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA289C433D2; Tue, 10 Jan 2023 18:21:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673374874; bh=uGACMhsOpM7hfjg2xI4r2v2groQOxRMt8vRjIuOUL1o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1GLlUL/+UnluxyeVgO7r+TwNOMSSnhYl2MompPUAOmKOpLGm+3mei3kNLoZLF3Hr8 6vEcZJPbZn0ukHeYHhJUpy9vIuoIgP1/lTcHCisLxR8N/oo5xNxZlHNxfYzWOvuZvW JF1degPcJYdBMx/94Ne1O4gfmTd6K70QbrkXw6oI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pavel Begunkov , Jens Axboe Subject: [PATCH 6.1 136/159] io_uring: pin context while queueing deferred tw Date: Tue, 10 Jan 2023 19:04:44 +0100 Message-Id: <20230110180022.727454346@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230110180018.288460217@linuxfoundation.org> References: <20230110180018.288460217@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Pavel Begunkov commit 9ffa13ff78a0a55df968a72d6f0ebffccee5c9f4 upstream. Unlike normal tw, nothing prevents deferred tw to be executed right after an tw item added to ->work_llist in io_req_local_work_add(). For instance, the waiting task may get waken up by CQ posting or a normal tw. Thus we need to pin the ring for the rest of io_req_local_work_add() Cc: stable@vger.kernel.org Fixes: c0e0d6ba25f18 ("io_uring: add IORING_SETUP_DEFER_TASKRUN") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/1a79362b9c10b8523ef70b061d96523650a23344.1672795998.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/io_uring.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1109,13 +1109,18 @@ static void io_req_local_work_add(struct { struct io_ring_ctx *ctx = req->ctx; - if (!llist_add(&req->io_task_work.node, &ctx->work_llist)) + percpu_ref_get(&ctx->refs); + + if (!llist_add(&req->io_task_work.node, &ctx->work_llist)) { + percpu_ref_put(&ctx->refs); return; + } /* need it for the following io_cqring_wake() */ smp_mb__after_atomic(); if (unlikely(atomic_read(&req->task->io_uring->in_idle))) { io_move_task_work_from_local(ctx); + percpu_ref_put(&ctx->refs); return; } @@ -1125,6 +1130,7 @@ static void io_req_local_work_add(struct if (ctx->has_evfd) io_eventfd_signal(ctx); __io_cqring_wake(ctx); + percpu_ref_put(&ctx->refs); } static inline void __io_req_task_work_add(struct io_kiocb *req, bool allow_local)