From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1768234AbcHRObA (ORCPT ); Thu, 18 Aug 2016 10:31:00 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37432 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1950327AbcHROPj (ORCPT ); Thu, 18 Aug 2016 10:15:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yi Zhang , Dan Williams , Jens Axboe Subject: [PATCH 4.7 145/186] block: fix bdi vs gendisk lifetime mismatch Date: Thu, 18 Aug 2016 15:59:22 +0200 Message-Id: <20160818135938.444245096@linuxfoundation.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160818135932.219369981@linuxfoundation.org> References: <20160818135932.219369981@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit df08c32ce3be5be138c1dbfcba203314a3a7cd6f upstream. The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [] dump_stack+0x63/0x87 [] __warn+0xd1/0xf0 [] warn_slowpath_fmt+0x5f/0x80 [] sysfs_warn_dup+0x64/0x80 [] sysfs_create_dir_ns+0x7e/0x90 [] kobject_add_internal+0xaa/0x320 [] ? vsnprintf+0x34e/0x4d0 [] kobject_add+0x75/0xd0 [] ? mutex_lock+0x12/0x2f [] device_add+0x125/0x610 [] device_create_groups_vargs+0xd8/0x100 [] device_create_vargs+0x1c/0x20 [] bdi_register+0x8c/0x180 [] bdi_register_dev+0x27/0x30 [] add_disk+0x175/0x4a0 Reported-by: Yi Zhang Tested-by: Yi Zhang Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman Fixed up missing 0 return in bdi_register_owner(). Signed-off-by: Jens Axboe --- block/genhd.c | 2 +- include/linux/backing-dev-defs.h | 1 + include/linux/backing-dev.h | 1 + mm/backing-dev.c | 19 +++++++++++++++++++ 4 files changed, 22 insertions(+), 1 deletion(-) --- a/block/genhd.c +++ b/block/genhd.c @@ -613,7 +613,7 @@ void add_disk(struct gendisk *disk) /* Register BDI before referencing it from bdev */ bdi = &disk->queue->backing_dev_info; - bdi_register_dev(bdi, disk_devt(disk)); + bdi_register_owner(bdi, disk_to_dev(disk)); blk_register_region(disk_devt(disk), disk->minors, NULL, exact_match, exact_lock, disk); --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -163,6 +163,7 @@ struct backing_dev_info { wait_queue_head_t wb_waitq; struct device *dev; + struct device *owner; struct timer_list laptop_mode_wb_timer; --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -24,6 +24,7 @@ __printf(3, 4) int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...); int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner); void bdi_unregister(struct backing_dev_info *bdi); int __must_check bdi_setup_and_register(struct backing_dev_info *, char *); --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -825,6 +825,20 @@ int bdi_register_dev(struct backing_dev_ } EXPORT_SYMBOL(bdi_register_dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) +{ + int rc; + + rc = bdi_register(bdi, NULL, "%u:%u", MAJOR(owner->devt), + MINOR(owner->devt)); + if (rc) + return rc; + bdi->owner = owner; + get_device(owner); + return 0; +} +EXPORT_SYMBOL(bdi_register_owner); + /* * Remove bdi from bdi_list, and ensure that it is no longer visible */ @@ -849,6 +863,11 @@ void bdi_unregister(struct backing_dev_i device_unregister(bdi->dev); bdi->dev = NULL; } + + if (bdi->owner) { + put_device(bdi->owner); + bdi->owner = NULL; + } } void bdi_exit(struct backing_dev_info *bdi)