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 5DC7C1DFFB; Thu, 15 Aug 2024 14:36:01 +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=1723732561; cv=none; b=QZcqKlqWOeNQCByQcOpPi8qT3mmeAZp486Y4l+2Xu//xOd+044SX7ayjpcHLqvfTpvMmrI1igW/MLu9OZ2qcf8ZiQ54mjmFgO5L7QGb3T4u9kgqEhLv0seDDdoLkdllOXUjHEu/gD9BSCKCBFDyvvhNMyqtnd6xpAgpmRGvbdtI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723732561; c=relaxed/simple; bh=G/VehMVDKo3+r3JCitmYOqtBlhi1kPj6jTk61mE7SrY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ljDiJsdAOAAX9O0GT9P62xA32yYIBwI4scZ7WVcrVIvbmLv3WkavuVBc0moVtwscaSMIib3NQzfHfPP4wvF0izEFGCJxQcGCDqzoW8sqxVS2cZWd10+aQGrr/VHWcW7mGi1rUL0++ZX9xRiaO5HqAfFkTsaDyFLVy/rGg6Vkibo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tN0QV2h0; 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="tN0QV2h0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4A83C32786; Thu, 15 Aug 2024 14:36:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723732561; bh=G/VehMVDKo3+r3JCitmYOqtBlhi1kPj6jTk61mE7SrY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tN0QV2h0vLX25z8V7/lo1609QHmfCnf59BcuraiGQS6+DXcn9tmK+Q2Svnu0mzDlY lP5qXS27zedMLYBso6IkbcqSM/+RI/0yPbYNzK/1U+s0dLSwJZOL9JyFnE3uFuMf1C bBfZ05Gd/J6nutr0bPtQyLWXmwAKggKecgTXIR1k= 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 5.10 186/352] io_uring/io-wq: limit retrying worker initialisation Date: Thu, 15 Aug 2024 15:24:12 +0200 Message-ID: <20240815131926.467774043@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131919.196120297@linuxfoundation.org> References: <20240815131919.196120297@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 5.10-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 @@ -19,6 +19,7 @@ #include "io-wq.h" #define WORKER_IDLE_TIMEOUT (5 * HZ) +#define WORKER_INIT_LIMIT 3 enum { IO_WORKER_F_UP = 1, /* up and active */ @@ -54,6 +55,7 @@ struct io_worker { unsigned long create_state; struct callback_head create_work; int create_index; + int init_retries; union { struct rcu_head rcu; @@ -732,7 +734,7 @@ 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 @@ -740,6 +742,8 @@ 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: @@ -766,7 +770,7 @@ static void create_worker_cont(struct ca io_init_new_worker(wqe, 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_wqe_acct *acct = io_wqe_get_acct(worker); atomic_dec(&acct->nr_running); @@ -831,7 +835,7 @@ fail: tsk = create_io_thread(io_wqe_worker, worker, wqe->node); if (!IS_ERR(tsk)) { io_init_new_worker(wqe, 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 {