From patchwork Fri Feb 9 18:44:04 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 10209801 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 67E6E60245 for ; Fri, 9 Feb 2018 18:44:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 582D329831 for ; Fri, 9 Feb 2018 18:44:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4D0B629864; Fri, 9 Feb 2018 18:44:10 +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=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AE36C29831 for ; Fri, 9 Feb 2018 18:44:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752392AbeBISoI (ORCPT ); Fri, 9 Feb 2018 13:44:08 -0500 Received: from esa1.hgst.iphmx.com ([68.232.141.245]:4891 "EHLO esa1.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752384AbeBISoH (ORCPT ); Fri, 9 Feb 2018 13:44:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1518201847; x=1549737847; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=xzpMitTD5Ey0veRvXfUEq0R0X4EvCxwxcj9UgoG/vCU=; b=Qylz1ic7zJxcFJbrfNfCmRTw2z2Vy4ZhpVDIV8IZqPG5cIB2PwqDBS7F K0yMjCr0MJeS2Tx2XPx+q3upaiR2DmFmTfrPHm0inxXjhKt5Umo+6O0x0 nbA5q94Jl/eu3w5f9YlUOZwClNo15Vn6ZcwvwDPiYUs9QdqVMmdJ+PHzZ Cba6dc048si75rPB9xBsCCNb9LV4z56kT2oWH+jqsa1GDix3+DCakTyTu /krixZydKGkoS9XTkZzbv9+U7LtYtkwZPWjRFeUWdnb+kOcWynYE9V3nh ui/hL9KBAq/rMOuc4eApv7E3rkVwVVKQOtsmZJnkym3puI8m4n9LjSlPD w==; X-IronPort-AV: E=Sophos;i="5.46,483,1511798400"; d="scan'208";a="174009667" Received: from h199-255-45-15.hgst.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 10 Feb 2018 02:44:06 +0800 Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP; 09 Feb 2018 10:38:23 -0800 Received: from thinkpad-bart.sdcorp.global.sandisk.com (HELO thinkpad-bart.int.fusionio.com) ([10.11.171.236]) by uls-op-cesaip02.wdc.com with ESMTP; 09 Feb 2018 10:44:06 -0800 From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Jan Kara , Joseph Qi , Bart Van Assche , Philipp Reisner , Ulf Hansson , Kees Cook Subject: [PATCH v3 2/3] block: Fix a race between the cgroup code and request queue initialization Date: Fri, 9 Feb 2018 10:44:04 -0800 Message-Id: <20180209184405.25835-3-bart.vanassche@wdc.com> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180209184405.25835-1-bart.vanassche@wdc.com> References: <20180209184405.25835-1-bart.vanassche@wdc.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Initialize the request queue lock earlier such that the following race can no longer occur: blk_init_queue_node() blkcg_print_blkgs() blk_alloc_queue_node (1) q->queue_lock = &q->__queue_lock (2) blkcg_init_queue(q) (3) spin_lock_irq(blkg->q->queue_lock) (4) q->queue_lock = lock (5) spin_unlock_irq(blkg->q->queue_lock) (6) (1) allocate an uninitialized queue; (2) initialize queue_lock to its default internal lock; (3) initialize blkcg part of request queue, which will create blkg and then insert it to blkg_list; (4) traverse blkg_list and find the created blkg, and then take its queue lock, here it is the default *internal lock*; (5) *race window*, now queue_lock is overridden with *driver specified lock*; (6) now unlock *driver specified lock*, not the locked *internal lock*, unlock balance breaks. The changes in this patch are as follows: - Move the .queue_lock initialization from blk_init_queue_node() into blk_alloc_queue_node(). - Only override the .queue_lock pointer for legacy queues because it is not useful for blk-mq queues to override this pointer. - For all all block drivers that initialize .queue_lock explicitly, change the blk_alloc_queue() call in the driver into a blk_alloc_queue_node() call and remove the explicit .queue_lock initialization. Additionally, initialize the spin lock that will be used as queue lock earlier if necessary. Reported-by: Joseph Qi Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Joseph Qi Cc: Philipp Reisner Cc: Ulf Hansson Cc: Kees Cook --- block/blk-core.c | 24 ++++++++++++++++-------- drivers/block/drbd/drbd_main.c | 3 +-- drivers/block/umem.c | 7 +++---- 3 files changed, 20 insertions(+), 14 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index e873a24bf82d..41c74b37be85 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -888,6 +888,19 @@ static void blk_rq_timed_out_timer(struct timer_list *t) kblockd_schedule_work(&q->timeout_work); } +/** + * blk_alloc_queue_node - allocate a request queue + * @gfp_mask: memory allocation flags + * @node_id: NUMA node to allocate memory from + * @lock: For legacy queues, pointer to a spinlock that will be used to e.g. + * serialize calls to the legacy .request_fn() callback. Ignored for + * blk-mq request queues. + * + * Note: pass the queue lock as the third argument to this function instead of + * setting the queue lock pointer explicitly to avoid triggering a sporadic + * crash in the blkcg code. This function namely calls blkcg_init_queue() and + * the queue lock pointer must be set before blkcg_init_queue() is called. + */ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id, spinlock_t *lock) { @@ -940,11 +953,8 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id, mutex_init(&q->sysfs_lock); spin_lock_init(&q->__queue_lock); - /* - * By default initialize queue_lock to internal lock and driver can - * override it later if need be. - */ - q->queue_lock = &q->__queue_lock; + if (!q->mq_ops) + q->queue_lock = lock ? : &q->__queue_lock; /* * A queue starts its life with bypass turned on to avoid @@ -1031,13 +1041,11 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) { struct request_queue *q; - q = blk_alloc_queue_node(GFP_KERNEL, node_id, NULL); + q = blk_alloc_queue_node(GFP_KERNEL, node_id, lock); if (!q) return NULL; q->request_fn = rfn; - if (lock) - q->queue_lock = lock; if (blk_init_allocated_queue(q) < 0) { blk_cleanup_queue(q); return NULL; diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 0a0394aa1b9c..185f1ef00a7c 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -2816,7 +2816,7 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig drbd_init_set_defaults(device); - q = blk_alloc_queue(GFP_KERNEL); + q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE, &resource->req_lock); if (!q) goto out_no_q; device->rq_queue = q; @@ -2848,7 +2848,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig /* Setting the max_hw_sectors to an odd value of 8kibyte here This triggers a max_bio_size message upon first attach or connect */ blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8); - q->queue_lock = &resource->req_lock; device->md_io.page = alloc_page(GFP_KERNEL); if (!device->md_io.page) diff --git a/drivers/block/umem.c b/drivers/block/umem.c index 8077123678ad..5c7fb8cc4149 100644 --- a/drivers/block/umem.c +++ b/drivers/block/umem.c @@ -888,13 +888,14 @@ static int mm_pci_probe(struct pci_dev *dev, const struct pci_device_id *id) card->Active = -1; /* no page is active */ card->bio = NULL; card->biotail = &card->bio; + spin_lock_init(&card->lock); - card->queue = blk_alloc_queue(GFP_KERNEL); + card->queue = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE, + &card->lock); if (!card->queue) goto failed_alloc; blk_queue_make_request(card->queue, mm_make_request); - card->queue->queue_lock = &card->lock; card->queue->queuedata = card; tasklet_init(&card->tasklet, process_page, (unsigned long)card); @@ -968,8 +969,6 @@ static int mm_pci_probe(struct pci_dev *dev, const struct pci_device_id *id) dev_printk(KERN_INFO, &card->dev->dev, "Window size %d bytes, IRQ %d\n", data, dev->irq); - spin_lock_init(&card->lock); - pci_set_drvdata(dev, card); if (pci_write_cmd != 0x0F) /* If not Memory Write & Invalidate */