From patchwork Wed Feb 8 20:09:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Jeffery X-Patchwork-Id: 652070 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 2BA37C05027 for ; Wed, 8 Feb 2023 20:11:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232020AbjBHULq (ORCPT ); Wed, 8 Feb 2023 15:11:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232018AbjBHULp (ORCPT ); Wed, 8 Feb 2023 15:11:45 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77F1F34001 for ; Wed, 8 Feb 2023 12:11:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675887059; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=pkpGIxstJz2N9eQc0UMJE5ogLSVhp75UoejwnhOmCxs=; b=jJ44REXbjYWYlGWjAhweqQMsNxYaWiYzs9Kdi9SbHYxuay10gvHzbYGi4dKzCWMGZsvcEU FSp4uQ+jxJGdxPEMvnVUq1tsQ8VgjtKM9UJapiNI5XOEaKiNK4h1TC/nqD98FYtcaWmsnM GKXi825ml/dj5pSrg2E5dofguiM+apc= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-22-kT6d-ytvNSaIgPYixMKvMA-1; Wed, 08 Feb 2023 15:10:54 -0500 X-MC-Unique: kT6d-ytvNSaIgPYixMKvMA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F180038123A1; Wed, 8 Feb 2023 20:10:53 +0000 (UTC) Received: from fedora-work.redhat.com (unknown [10.22.10.165]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9BAC1492C3F; Wed, 8 Feb 2023 20:10:47 +0000 (UTC) From: David Jeffery To: target-devel@vger.kernel.org Cc: "Martin K . Petersen" , Mike Christie , Maurizio Lombardi , Laurence Oberman , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, David Jeffery Subject: [PATCH] scsi: target: iscsi: set memalloc_noio with loopback network connections Date: Wed, 8 Feb 2023 15:09:57 -0500 Message-Id: <20230208200957.14073-1-djeffery@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org If an admin connects an iscsi initiator to an iscsi target on the same system, the iscsi connection is vulnerable to deadlocks during memory allocations. Memory allocations in the target task accepting the I/O from the initiator can wait on the initiator's I/O when the system is under memory pressure, causing a deadlock situation between the iscsi target and initiator. When in this configuration, the deadlock scenario can be avoided by use of GFP_NOIO allocations. Rather than force all configurations to use NOIO, memalloc_noio_save/restore can be used to force GFP_NOIO allocations only when in this loopback configuration. Signed-off-by: David Jeffery Tested-by: Laurence Oberman Reviewed-by: Laurence Oberman --- drivers/target/iscsi/iscsi_target.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index baf4da7bb3b4..a68e47e2cdf9 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -4168,7 +4169,10 @@ int iscsi_target_rx_thread(void *arg) { int rc; struct iscsit_conn *conn = arg; + struct dst_entry *dst; bool conn_freed = false; + bool loopback = false; + unsigned int flags; /* * Allow ourselves to be interrupted by SIGINT so that a @@ -4186,8 +4190,25 @@ int iscsi_target_rx_thread(void *arg) if (!conn->conn_transport->iscsit_get_rx_pdu) return 0; + /* + * If the iscsi connection is over a loopback device from using + * iscsi and iscsit on the same system, we need to set memalloc_noio to + * prevent memory allocation deadlocks between target and initiator. + */ + rcu_read_lock(); + dst = rcu_dereference(conn->sock->sk->sk_dst_cache); + if (dst && dst->dev && dst->dev->flags & IFF_LOOPBACK) + loopback = true; + rcu_read_unlock(); + + if (loopback) + flags = memalloc_noio_save(); + conn->conn_transport->iscsit_get_rx_pdu(conn); + if (loopback) + memalloc_noio_restore(flags); + if (!signal_pending(current)) atomic_set(&conn->transport_failed, 1); iscsit_take_action_for_connection_exit(conn, &conn_freed);