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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45653C282D7 for ; Mon, 11 Feb 2019 15:15:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 160B4222A7 for ; Mon, 11 Feb 2019 15:15:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549898146; bh=S1LFC4WpHIC7BmPAQt+y5rz84ctxLOudUejV+1NJ1WY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FKWkT8zifHuzikaCIeKXiMfaDELV4j1CgwRMi0z5vNe50azUZFojp6LKI+BBirpQJ Uc1b1GT3FSty5Q/aDqDbMxVLrMg4jDfrPQFpfobxEMk7RFPsK8BV2CH+wESvtjM25h c3mm9LQEkKchyrJj4X9oggzaaoZ7+IskchVk8H90= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391364AbfBKPHc (ORCPT ); Mon, 11 Feb 2019 10:07:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:57324 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731524AbfBKPHb (ORCPT ); Mon, 11 Feb 2019 10:07:31 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 02C46217D9; Mon, 11 Feb 2019 15:07:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549897650; bh=S1LFC4WpHIC7BmPAQt+y5rz84ctxLOudUejV+1NJ1WY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rtzo8cMv1d3UBDEkR8jiXZ4dzjM/0mCxg+6D1WYUZi3wvDZgmATrhbkleCxb78Qkr /J9BrCkWlFcS/n329MAbt/Moy8R/MxRwcAi8Dzg2cj9JQeqEPO8cq/PJKECzO2EKgl 6SVreOI3oZkDrv7AiYqIx4COA+pQs8Qlfijr3xVs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jia-Ju Bai , Lars Ellenberg , Roland Kammerer , Jens Axboe , Sasha Levin Subject: [PATCH 4.9 068/137] drbd: narrow rcu_read_lock in drbd_sync_handshake Date: Mon, 11 Feb 2019 15:19:09 +0100 Message-Id: <20190211141818.294979856@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141811.964925535@linuxfoundation.org> References: <20190211141811.964925535@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit d29e89e34952a9ad02c77109c71a80043544296e ] 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 Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- 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 942384f34e22..77d0f80f62f9 100644 --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -3421,7 +3421,7 @@ 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) @@ -3472,8 +3472,12 @@ 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); @@ -3512,9 +3516,6 @@ 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 -- 2.19.1