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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B139CC282C8 for ; Mon, 28 Jan 2019 17:35:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 802EB2147A for ; Mon, 28 Jan 2019 17:35:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548696909; bh=OlsiW8zHmCCN5goS58S0YW87RtfjyOChk7jWdaj6rfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZCQcodfxh95whMlf/4VWIam2yCQF8cgMJBn8G5ABoNuYVW9FpbMsappwJk6WNHUm+ afdvt9AU2e8WuFHs9UefuWLTn83YwjoQeM5p/C9mdh8MiT2uScunm0GDv7xLsDKjTS Vwa0Wi/Wps07BG7aXdmWXtSF9MmYCzPLd3bOaFa4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729914AbfA1Pzb (ORCPT ); Mon, 28 Jan 2019 10:55:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:41406 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729909AbfA1Pzb (ORCPT ); Mon, 28 Jan 2019 10:55:31 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B4C1620855; Mon, 28 Jan 2019 15:55:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548690930; bh=OlsiW8zHmCCN5goS58S0YW87RtfjyOChk7jWdaj6rfI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cSB6swBpiKCpKDw37DYfe4cZbgOm+VHovYJfPiIjx+Lest13RcK3ZpVxpIKsD0qbX ySBlD7t/8sgb11iF8zywWb7OavU4dhiAP7AQHF0aB22j2h806gxJEnVXHVVZwl3/D5 hpToealI0ZwWQ/JSkeGddbq2/c0V+g1ABeyN1BNw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Roland Kammerer , Jens Axboe , Sasha Levin , drbd-dev@lists.linbit.com, linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 4.20 237/304] drbd: narrow rcu_read_lock in drbd_sync_handshake Date: Mon, 28 Jan 2019 10:42:34 -0500 Message-Id: <20190128154341.47195-237-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128154341.47195-1-sashal@kernel.org> References: <20190128154341.47195-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Roland Kammerer [ 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 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 -- 2.19.1