From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754116AbeDWCcJ (ORCPT ); Sun, 22 Apr 2018 22:32:09 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52464 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753967AbeDWCbX (ORCPT ); Sun, 22 Apr 2018 22:31:23 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com, Nitzan Carmi , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 12/22] nvme: Avoid flush dependency in delete controller flow Date: Sun, 22 Apr 2018 19:32:17 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20180423023150.GA21533@linux.vnet.ibm.com> References: <20180423023150.GA21533@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18042302-0036-0000-0000-000002E8AF7D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008903; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000257; SDB=6.01021888; UDB=6.00521536; IPR=6.00801123; MB=3.00020719; MTD=3.00000008; XFM=3.00000015; UTC=2018-04-23 02:31:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042302-0037-0000-0000-00004414FD96 Message-Id: <1524450747-22778-12-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-23_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804230025 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nitzan Carmi The nvme_delete_ctrl() function queues a work item on a MEM_RECLAIM queue (nvme_delete_wq), which eventually calls cleanup_srcu_struct(), which in turn flushes a delayed work from an !MEM_RECLAIM queue. This is unsafe as we might trigger deadlocks under severe memory pressure. Since we don't ever invoke call_srcu(), it is safe to use the shiny new _quiesced() version of srcu cleanup, thus avoiding that flush dependency. This commit makes that change. Signed-off-by: Nitzan Carmi Signed-off-by: Paul E. McKenney Reviewed-by: Max Gurtovoy --- drivers/nvme/host/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 9df4f71e58ca..c3cea8a29843 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -349,7 +349,7 @@ static void nvme_free_ns_head(struct kref *ref) nvme_mpath_remove_disk(head); ida_simple_remove(&head->subsys->ns_ida, head->instance); list_del_init(&head->entry); - cleanup_srcu_struct(&head->srcu); + cleanup_srcu_struct_quiesced(&head->srcu); kfree(head); } -- 2.5.2