From patchwork Thu Dec 20 16:23:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lars Ellenberg X-Patchwork-Id: 10739123 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B992D746 for ; Thu, 20 Dec 2018 16:29:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A7BB02906D for ; Thu, 20 Dec 2018 16:29:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9BDB8290BC; Thu, 20 Dec 2018 16:29:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 56AF32906D for ; Thu, 20 Dec 2018 16:29:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733065AbeLTQ3i (ORCPT ); Thu, 20 Dec 2018 11:29:38 -0500 Received: from mail09.linbit.com ([212.69.161.110]:49429 "EHLO mail09.linbit.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733010AbeLTQ3i (ORCPT ); Thu, 20 Dec 2018 11:29:38 -0500 Received: from soda.linbit (212-186-191-219.static.upcbusiness.at [212.186.191.219]) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTP id E7578103B4C3; Thu, 20 Dec 2018 17:23:44 +0100 (CET) From: Lars Ellenberg To: Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Cc: drbd-dev@lists.linbit.com Subject: [PATCH 01/17] drbd: narrow rcu_read_lock in drbd_sync_handshake Date: Thu, 20 Dec 2018 17:23:28 +0100 Message-Id: <20181220162344.8430-2-lars.ellenberg@linbit.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181220162344.8430-1-lars.ellenberg@linbit.com> References: <20181220162344.8430-1-lars.ellenberg@linbit.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Roland Kammerer So far there was the possibility that we called genlmsg_new(GFP_NOIO)/mutex_lock() while holding an rcu_read_lock(). This included cases like: drbd_sync_handshake (acquire the RCU lock) drbd_asb_recover_1p drbd_khelper drbd_bcast_event genlmsg_new(GFP_NOIO) --> may sleep drbd_sync_handshake (acquire the RCU lock) drbd_asb_recover_1p drbd_khelper notify_helper genlmsg_new(GFP_NOIO) --> may sleep drbd_sync_handshake (acquire the RCU lock) drbd_asb_recover_1p drbd_khelper notify_helper mutex_lock --> may sleep While using GFP_ATOMIC whould have been possible in the first two cases, the real fix is to narrow the rcu_read_lock. Reported-by: Jia-Ju Bai Reviewed-by: Lars Ellenberg Signed-off-by: Roland Kammerer --- drivers/block/drbd/drbd_receiver.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index 61c392752fe4..1b9822f264d2 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -3364,7 +3364,7 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device, enum drbd_conns rv = C_MASK; enum drbd_disk_state mydisk; struct net_conf *nc; - int hg, rule_nr, rr_conflict, tentative; + int hg, rule_nr, rr_conflict, tentative, always_asbp; mydisk = device->state.disk; if (mydisk == D_NEGOTIATING) @@ -3415,8 +3415,12 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device, rcu_read_lock(); nc = rcu_dereference(peer_device->connection->net_conf); + always_asbp = nc->always_asbp; + rr_conflict = nc->rr_conflict; + tentative = nc->tentative; + rcu_read_unlock(); - if (hg == 100 || (hg == -100 && nc->always_asbp)) { + if (hg == 100 || (hg == -100 && always_asbp)) { int pcount = (device->state.role == R_PRIMARY) + (peer_role == R_PRIMARY); int forced = (hg == -100); @@ -3455,9 +3459,6 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device, "Sync from %s node\n", (hg < 0) ? "peer" : "this"); } - rr_conflict = nc->rr_conflict; - tentative = nc->tentative; - rcu_read_unlock(); if (hg == -100) { /* FIXME this log message is not correct if we end up here