From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28619C433EF for ; Mon, 31 Jan 2022 11:35:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377775AbiAaLdc (ORCPT ); Mon, 31 Jan 2022 06:33:32 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:56054 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377602AbiAaLXL (ORCPT ); Mon, 31 Jan 2022 06:23:11 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 97C8E60ED0; Mon, 31 Jan 2022 11:23:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91BC5C340E8; Mon, 31 Jan 2022 11:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643628190; bh=ZOL6rUN3wT1gBttG/d1EVyzJDAYDIoRciQx+cPr5nZE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=szAaO1r31LGCd//5g4PfT1CCAUN9c1wrX7bNXdawJDMFBIQnuQlRt/wrCkxjdt0nt KFiEsErAUykWAmyz1cMV29VYmT2OqCpmHLWr7S4244KA14O9BDE5O9R0WFog/5Y3lC HmPeov43AM8oD26JN6PeVa7lMGNWdQ6UQUkWjYFU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dylan Yudaken , Jens Axboe , Sasha Levin Subject: [PATCH 5.16 153/200] io_uring: fix bug in slow unregistering of nodes Date: Mon, 31 Jan 2022 11:56:56 +0100 Message-Id: <20220131105238.710162802@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220131105233.561926043@linuxfoundation.org> References: <20220131105233.561926043@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dylan Yudaken [ Upstream commit b36a2050040b2d839bdc044007cdd57101d7f881 ] In some cases io_rsrc_ref_quiesce will call io_rsrc_node_switch_start, and then immediately flush the delayed work queue &ctx->rsrc_put_work. However the percpu_ref_put does not immediately destroy the node, it will be called asynchronously via RCU. That ends up with io_rsrc_node_ref_zero only being called after rsrc_put_work has been flushed, and so the process ends up sleeping for 1 second unnecessarily. This patch executes the put code immediately if we are busy quiescing. Fixes: 4a38aed2a0a7 ("io_uring: batch reap of dead file registrations") Signed-off-by: Dylan Yudaken Link: https://lore.kernel.org/r/20220121123856.3557884-1-dylany@fb.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 15f303180d70c..698db7fb62e06 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7761,10 +7761,15 @@ static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref) struct io_ring_ctx *ctx = node->rsrc_data->ctx; unsigned long flags; bool first_add = false; + unsigned long delay = HZ; spin_lock_irqsave(&ctx->rsrc_ref_lock, flags); node->done = true; + /* if we are mid-quiesce then do not delay */ + if (node->rsrc_data->quiesce) + delay = 0; + while (!list_empty(&ctx->rsrc_ref_list)) { node = list_first_entry(&ctx->rsrc_ref_list, struct io_rsrc_node, node); @@ -7777,7 +7782,7 @@ static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref) spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags); if (first_add) - mod_delayed_work(system_wq, &ctx->rsrc_put_work, HZ); + mod_delayed_work(system_wq, &ctx->rsrc_put_work, delay); } static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx) -- 2.34.1