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 97C8B18801A; Tue, 30 Jul 2024 16:57:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722358671; cv=none; b=YOz4Vf+wfGjIY1qEjnEx9nfRJEMU0K6RlASOKUX3Jec6wgCfGmYrYV/re/kbo17QAcVZ7/DcSpPC+/GfGdAvN/NTeh01ce5+94ELWE5sH6wabJpdlDH9TxIFJcKySvN5HhEvG42k7huJjqRmiUhoCzMxIK+a1dPHuUUUqmy89cE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722358671; c=relaxed/simple; bh=4QmBtjZH7KCbl/ErpgFeVjje1Io/pGkLXB9fQfcjO4Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BhQIva5P7GsR83KguILBj8x+sjjzEkWMe4gFje4U+hG107u21DWcZ1BWseeSmZzmGloTpvAI+k+jWHTAFgS5lY3QeiShgi7i1wFeklx3NcgMD67UHfIVwi6ZYYTX7R84BtJiyNBB12ZRJuJhK0vd6xKS/jhrfUX02H32jC/JWfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WgG82LGI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WgG82LGI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11FE7C4AF0E; Tue, 30 Jul 2024 16:57:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1722358671; bh=4QmBtjZH7KCbl/ErpgFeVjje1Io/pGkLXB9fQfcjO4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WgG82LGI4N/QjzHTxxialNG8HBGy0n/wwAR/gVVEZhZ7Eunpr1lL2UyivvYCBl6t/ gyDQnNwR8Bwq9+9ustlm4OyHD/u8pO9p857xInLMwIhlp0xx1q6ULNv+LAla5C88uK haUWSFpkFbzpsY1MbjO+EKMBA8p3/inZCQdr9q4Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Julian Orth , Pavel Begunkov , Jens Axboe Subject: [PATCH 6.6 384/568] io_uring/io-wq: limit retrying worker initialisation Date: Tue, 30 Jul 2024 17:48:11 +0200 Message-ID: <20240730151654.876108353@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240730151639.792277039@linuxfoundation.org> References: <20240730151639.792277039@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavel Begunkov commit 0453aad676ff99787124b9b3af4a5f59fbe808e2 upstream. If io-wq worker creation fails, we retry it by queueing up a task_work. tasK_work is needed because it should be done from the user process context. The problem is that retries are not limited, and if queueing a task_work is the reason for the failure, we might get into an infinite loop. It doesn't seem to happen now but it would with the following patch executing task_work in the freezer's loop. For now, arbitrarily limit the number of attempts to create a worker. Cc: stable@vger.kernel.org Fixes: 3146cba99aa28 ("io-wq: make worker creation resilient against signals") Reported-by: Julian Orth Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/8280436925db88448c7c85c6656edee1a43029ea.1720634146.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- io_uring/io-wq.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -23,6 +23,7 @@ #include "io_uring.h" #define WORKER_IDLE_TIMEOUT (5 * HZ) +#define WORKER_INIT_LIMIT 3 enum { IO_WORKER_F_UP = 0, /* up and active */ @@ -59,6 +60,7 @@ struct io_worker { unsigned long create_state; struct callback_head create_work; + int init_retries; union { struct rcu_head rcu; @@ -746,7 +748,7 @@ static bool io_wq_work_match_all(struct return true; } -static inline bool io_should_retry_thread(long err) +static inline bool io_should_retry_thread(struct io_worker *worker, long err) { /* * Prevent perpetual task_work retry, if the task (or its group) is @@ -754,6 +756,8 @@ static inline bool io_should_retry_threa */ if (fatal_signal_pending(current)) return false; + if (worker->init_retries++ >= WORKER_INIT_LIMIT) + return false; switch (err) { case -EAGAIN: @@ -780,7 +784,7 @@ static void create_worker_cont(struct ca io_init_new_worker(wq, worker, tsk); io_worker_release(worker); return; - } else if (!io_should_retry_thread(PTR_ERR(tsk))) { + } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) { struct io_wq_acct *acct = io_wq_get_acct(worker); atomic_dec(&acct->nr_running); @@ -847,7 +851,7 @@ fail: tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE); if (!IS_ERR(tsk)) { io_init_new_worker(wq, worker, tsk); - } else if (!io_should_retry_thread(PTR_ERR(tsk))) { + } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) { kfree(worker); goto fail; } else {