From patchwork Tue Jun 11 23:26:10 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 10988375 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 52A8613AD for ; Tue, 11 Jun 2019 23:40:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3F9F4284BD for ; Tue, 11 Jun 2019 23:40:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 32E8128565; Tue, 11 Jun 2019 23:40:30 +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=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id EA98A284BD for ; Tue, 11 Jun 2019 23:40:28 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id DECFF21290D5C; Tue, 11 Jun 2019 16:40:28 -0700 (PDT) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=134.134.136.65; helo=mga03.intel.com; envelope-from=dan.j.williams@intel.com; receiver=linux-nvdimm@lists.01.org Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 8E3F121290D20 for ; Tue, 11 Jun 2019 16:40:27 -0700 (PDT) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2019 16:40:27 -0700 X-ExtLoop1: 1 Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by fmsmga007.fm.intel.com with ESMTP; 11 Jun 2019 16:40:26 -0700 Subject: [PATCH 5/6] libnvdimm/bus: Fix wait_nvdimm_bus_probe_idle() ABBA deadlock From: Dan Williams To: linux-nvdimm@lists.01.org Date: Tue, 11 Jun 2019 16:26:10 -0700 Message-ID: <156029557026.419799.1378625476581339382.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <156029554317.419799.1324389595953183385.stgit@dwillia2-desk3.amr.corp.intel.com> References: <156029554317.419799.1324389595953183385.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP A multithreaded namespace creation/destruction stress test currently deadlocks with the following lockup signature: INFO: task ndctl:2924 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2924 1176 0x00000000 Call Trace: ? __schedule+0x27e/0x780 schedule+0x30/0xb0 wait_nvdimm_bus_probe_idle+0x8a/0xd0 [libnvdimm] ? finish_wait+0x80/0x80 uuid_store+0xe6/0x2e0 [libnvdimm] kernfs_fop_write+0xf0/0x1a0 vfs_write+0xb7/0x1b0 ksys_write+0x5c/0xd0 do_syscall_64+0x60/0x240 INFO: task ndctl:2923 blocked for more than 122 seconds. Tainted: G OE 5.2.0-rc4+ #3382 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ndctl D 0 2923 1175 0x00000000 Call Trace: ? __schedule+0x27e/0x780 ? __mutex_lock+0x489/0x910 schedule+0x30/0xb0 schedule_preempt_disabled+0x11/0x20 __mutex_lock+0x48e/0x910 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] ? __lock_acquire+0x23f/0x1710 ? nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] nvdimm_namespace_common_probe+0x95/0x4d0 [libnvdimm] __dax_pmem_probe+0x5e/0x210 [dax_pmem_core] ? nvdimm_bus_probe+0x1d0/0x2c0 [libnvdimm] dax_pmem_probe+0xc/0x20 [dax_pmem] nvdimm_bus_probe+0x90/0x2c0 [libnvdimm] really_probe+0xef/0x390 driver_probe_device+0xb4/0x100 In this sequence an 'nd_dax' device is being probed and trying to take the lock on its backing namespace to validate that the 'nd_dax' device indeed has exclusive access to the backing namespace. Meanwhile, another thread is trying to update the uuid property of that same backing namespace. So one thread is in the probe path trying to acquire the lock, and the other thread has acquired the lock and tries to flush the probe path. Fix this deadlock by not holding the namespace device_lock over the wait_nvdimm_bus_probe_idle() synchronization step. In turn this requires the device_lock to be held on entry to wait_nvdimm_bus_probe_idle() and subsequently dropped internally to wait_nvdimm_bus_probe_idle(). Cc: Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation") Cc: Vishal Verma Signed-off-by: Dan Williams --- drivers/nvdimm/bus.c | 17 +++++++++++------ drivers/nvdimm/region_devs.c | 4 ++++ 2 files changed, 15 insertions(+), 6 deletions(-) diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c index dfb93228d6a7..c1d26fca9c4c 100644 --- a/drivers/nvdimm/bus.c +++ b/drivers/nvdimm/bus.c @@ -887,10 +887,12 @@ void wait_nvdimm_bus_probe_idle(struct device *dev) do { if (nvdimm_bus->probe_active == 0) break; - nvdimm_bus_unlock(&nvdimm_bus->dev); + nvdimm_bus_unlock(dev); + device_unlock(dev); wait_event(nvdimm_bus->wait, nvdimm_bus->probe_active == 0); - nvdimm_bus_lock(&nvdimm_bus->dev); + device_lock(dev); + nvdimm_bus_lock(dev); } while (true); } @@ -1017,7 +1019,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm, case ND_CMD_ARS_START: case ND_CMD_CLEAR_ERROR: case ND_CMD_CALL: - dev_dbg(&nvdimm_bus->dev, "'%s' command while read-only.\n", + dev_dbg(dev, "'%s' command while read-only.\n", nvdimm ? nvdimm_cmd_name(cmd) : nvdimm_bus_cmd_name(cmd)); return -EPERM; @@ -1088,7 +1090,8 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm, goto out; } - nvdimm_bus_lock(&nvdimm_bus->dev); + device_lock(dev); + nvdimm_bus_lock(dev); rc = nd_cmd_clear_to_send(nvdimm_bus, nvdimm, func, buf); if (rc) goto out_unlock; @@ -1103,7 +1106,8 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm, nvdimm_account_cleared_poison(nvdimm_bus, clear_err->address, clear_err->cleared); } - nvdimm_bus_unlock(&nvdimm_bus->dev); + nvdimm_bus_unlock(dev); + device_unlock(dev); if (copy_to_user(p, buf, buf_len)) rc = -EFAULT; @@ -1112,7 +1116,8 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm, return rc; out_unlock: - nvdimm_bus_unlock(&nvdimm_bus->dev); + nvdimm_bus_unlock(dev); + device_unlock(dev); out: vfree(buf); return rc; diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 4fed9ce9c2fe..a15276cdec7d 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -422,10 +422,12 @@ static ssize_t available_size_show(struct device *dev, * memory nvdimm_bus_lock() is dropped, but that's userspace's * problem to not race itself. */ + device_lock(dev); nvdimm_bus_lock(dev); wait_nvdimm_bus_probe_idle(dev); available = nd_region_available_dpa(nd_region); nvdimm_bus_unlock(dev); + device_unlock(dev); return sprintf(buf, "%llu\n", available); } @@ -437,10 +439,12 @@ static ssize_t max_available_extent_show(struct device *dev, struct nd_region *nd_region = to_nd_region(dev); unsigned long long available = 0; + device_lock(dev); nvdimm_bus_lock(dev); wait_nvdimm_bus_probe_idle(dev); available = nd_region_allocatable_dpa(nd_region); nvdimm_bus_unlock(dev); + device_unlock(dev); return sprintf(buf, "%llu\n", available); }