tree: https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git 20211011-for-axboe-add-disk-error-handling head: 53099761729ca16d3bb36db8a8cc526f4eb08f28 commit: 53099761729ca16d3bb36db8a8cc526f4eb08f28 [24/24] block: add __must_check for *add_disk*() callers config: hexagon-randconfig-r041-20211019 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project d245f2e8597bfb52c34810a328d42b990e4af1a4) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git/com... git remote add mcgrof-next https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git git fetch --no-tags mcgrof-next 20211011-for-axboe-add-disk-error-handling git checkout 53099761729ca16d3bb36db8a8cc526f4eb08f28 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): add_disk(disk); ^~~~~~~~ ~~~~ 1 warning generated. vim +/warn_unused_result +5705 drivers/md/md.c a415c0f1062791 NeilBrown 2017-06-05 5620 efeb53c0e57213 NeilBrown 2009-01-09 5621 static int md_alloc(dev_t dev, char *name) ^1da177e4c3f41 Linus Torvalds 2005-04-16 5622 { 039b7225e6e987 NeilBrown 2017-04-12 5623 /* 039b7225e6e987 NeilBrown 2017-04-12 5624 * If dev is zero, name is the name of a device to allocate with 039b7225e6e987 NeilBrown 2017-04-12 5625 * an arbitrary minor number. It will be "md_???" 039b7225e6e987 NeilBrown 2017-04-12 5626 * If dev is non-zero it must be a device number with a MAJOR of 039b7225e6e987 NeilBrown 2017-04-12 5627 * MD_MAJOR or mdp_major. In this case, if "name" is NULL, then 039b7225e6e987 NeilBrown 2017-04-12 5628 * the device is being created by opening a node in /dev. 039b7225e6e987 NeilBrown 2017-04-12 5629 * If "name" is not NULL, the device is being created by 039b7225e6e987 NeilBrown 2017-04-12 5630 * writing to /sys/module/md_mod/parameters/new_array. 039b7225e6e987 NeilBrown 2017-04-12 5631 */ 48c9c27b8bcd2a Arjan van de Ven 2006-03-27 5632 static DEFINE_MUTEX(disks_mutex); 0d809b3837a0be Christoph Hellwig 2021-04-12 5633 struct mddev *mddev; ^1da177e4c3f41 Linus Torvalds 2005-04-16 5634 struct gendisk *disk; efeb53c0e57213 NeilBrown 2009-01-09 5635 int partitioned; efeb53c0e57213 NeilBrown 2009-01-09 5636 int shift; efeb53c0e57213 NeilBrown 2009-01-09 5637 int unit; 3830c62fef49f8 Greg Kroah-Hartman 2007-12-17 5638 int error ; ^1da177e4c3f41 Linus Torvalds 2005-04-16 5639 0d809b3837a0be Christoph Hellwig 2021-04-12 5640 /* 0d809b3837a0be Christoph Hellwig 2021-04-12 5641 * Wait for any previous instance of this device to be completely 0d809b3837a0be Christoph Hellwig 2021-04-12 5642 * removed (mddev_delayed_delete). d3374825ce57ba NeilBrown 2009-01-09 5643 */ e804ac780e2f01 Tejun Heo 2010-10-15 5644 flush_workqueue(md_misc_wq); d3374825ce57ba NeilBrown 2009-01-09 5645 48c9c27b8bcd2a Arjan van de Ven 2006-03-27 5646 mutex_lock(&disks_mutex); 0d809b3837a0be Christoph Hellwig 2021-04-12 5647 mddev = mddev_alloc(dev); 0d809b3837a0be Christoph Hellwig 2021-04-12 5648 if (IS_ERR(mddev)) { 0d809b3837a0be Christoph Hellwig 2021-04-12 5649 mutex_unlock(&disks_mutex); 0d809b3837a0be Christoph Hellwig 2021-04-12 5650 return PTR_ERR(mddev); 0d809b3837a0be Christoph Hellwig 2021-04-12 5651 } 0d809b3837a0be Christoph Hellwig 2021-04-12 5652 0d809b3837a0be Christoph Hellwig 2021-04-12 5653 partitioned = (MAJOR(mddev->unit) != MD_MAJOR); 0d809b3837a0be Christoph Hellwig 2021-04-12 5654 shift = partitioned ? MdpMinorShift : 0; 0d809b3837a0be Christoph Hellwig 2021-04-12 5655 unit = MINOR(mddev->unit) >> shift; efeb53c0e57213 NeilBrown 2009-01-09 5656 039b7225e6e987 NeilBrown 2017-04-12 5657 if (name && !dev) { efeb53c0e57213 NeilBrown 2009-01-09 5658 /* Need to ensure that 'name' is not a duplicate. efeb53c0e57213 NeilBrown 2009-01-09 5659 */ fd01b88c75a718 NeilBrown 2011-10-11 5660 struct mddev *mddev2; efeb53c0e57213 NeilBrown 2009-01-09 5661 spin_lock(&all_mddevs_lock); efeb53c0e57213 NeilBrown 2009-01-09 5662 efeb53c0e57213 NeilBrown 2009-01-09 5663 list_for_each_entry(mddev2, &all_mddevs, all_mddevs) efeb53c0e57213 NeilBrown 2009-01-09 5664 if (mddev2->gendisk && efeb53c0e57213 NeilBrown 2009-01-09 5665 strcmp(mddev2->gendisk->disk_name, name) == 0) { efeb53c0e57213 NeilBrown 2009-01-09 5666 spin_unlock(&all_mddevs_lock); 0d809b3837a0be Christoph Hellwig 2021-04-12 5667 error = -EEXIST; 0909dc448c98ed NeilBrown 2009-07-01 5668 goto abort; efeb53c0e57213 NeilBrown 2009-01-09 5669 } efeb53c0e57213 NeilBrown 2009-01-09 5670 spin_unlock(&all_mddevs_lock); ^1da177e4c3f41 Linus Torvalds 2005-04-16 5671 } 039b7225e6e987 NeilBrown 2017-04-12 5672 if (name && dev) 039b7225e6e987 NeilBrown 2017-04-12 5673 /* 039b7225e6e987 NeilBrown 2017-04-12 5674 * Creating /dev/mdNNN via "newarray", so adjust hold_active. 039b7225e6e987 NeilBrown 2017-04-12 5675 */ 039b7225e6e987 NeilBrown 2017-04-12 5676 mddev->hold_active = UNTIL_STOP; 8b76539823d715 NeilBrown 2009-01-09 5677 0909dc448c98ed NeilBrown 2009-07-01 5678 error = -ENOMEM; 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5679 disk = blk_alloc_disk(NUMA_NO_NODE); 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5680 if (!disk) 0909dc448c98ed NeilBrown 2009-07-01 5681 goto abort; 409c57f3801701 NeilBrown 2009-03-31 5682 efeb53c0e57213 NeilBrown 2009-01-09 5683 disk->major = MAJOR(mddev->unit); ^1da177e4c3f41 Linus Torvalds 2005-04-16 5684 disk->first_minor = unit << shift; 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5685 disk->minors = 1 << shift; efeb53c0e57213 NeilBrown 2009-01-09 5686 if (name) efeb53c0e57213 NeilBrown 2009-01-09 5687 strcpy(disk->disk_name, name); efeb53c0e57213 NeilBrown 2009-01-09 5688 else if (partitioned) ^1da177e4c3f41 Linus Torvalds 2005-04-16 5689 sprintf(disk->disk_name, "md_d%d", unit); ce7b0f46bbf4bf Greg Kroah-Hartman 2005-06-20 5690 else ^1da177e4c3f41 Linus Torvalds 2005-04-16 5691 sprintf(disk->disk_name, "md%d", unit); ^1da177e4c3f41 Linus Torvalds 2005-04-16 5692 disk->fops = &md_fops; ^1da177e4c3f41 Linus Torvalds 2005-04-16 5693 disk->private_data = mddev; 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5694 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5695 mddev->queue = disk->queue; 0f1d2e0643c544 Christoph Hellwig 2021-05-21 5696 blk_set_stacking_limits(&mddev->queue->limits); 56883a7ec85f5b Jens Axboe 2016-03-30 5697 blk_queue_write_cache(mddev->queue, true, true); 92850bbd712287 NeilBrown 2008-10-21 5698 /* Allow extended partitions. This makes the d3374825ce57ba NeilBrown 2009-01-09 5699 * 'mdp' device redundant, but we can't really 92850bbd712287 NeilBrown 2008-10-21 5700 * remove it now. 92850bbd712287 NeilBrown 2008-10-21 5701 */ 92850bbd712287 NeilBrown 2008-10-21 5702 disk->flags |= GENHD_FL_EXT_DEVT; a564e23f0f9975 Christoph Hellwig 2020-07-08 5703 disk->events |= DISK_EVENT_MEDIA_CHANGE; ^1da177e4c3f41 Linus Torvalds 2005-04-16 5704 mddev->gendisk = disk; b0140891a8cea3 NeilBrown 2011-05-10 @5705 add_disk(disk); b0140891a8cea3 NeilBrown 2011-05-10 5706 28dec870aaf704 Kent Overstreet 2018-06-07 5707 error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md"); 0909dc448c98ed NeilBrown 2009-07-01 5708 if (error) { 0909dc448c98ed NeilBrown 2009-07-01 5709 /* This isn't possible, but as kobject_init_and_add is marked 0909dc448c98ed NeilBrown 2009-07-01 5710 * __must_check, we must do something with the result 0909dc448c98ed NeilBrown 2009-07-01 5711 */ 9d48739ef19aa8 NeilBrown 2016-11-02 5712 pr_debug("md: cannot register %s/md - name in use\n", 5e55e2f5fc95b3 NeilBrown 2007-03-26 5713 disk->disk_name); 0909dc448c98ed NeilBrown 2009-07-01 5714 error = 0; 0909dc448c98ed NeilBrown 2009-07-01 5715 } 00bcb4ac7ee7e5 NeilBrown 2010-06-01 5716 if (mddev->kobj.sd && 00bcb4ac7ee7e5 NeilBrown 2010-06-01 5717 sysfs_create_group(&mddev->kobj, &md_bitmap_group)) 9d48739ef19aa8 NeilBrown 2016-11-02 5718 pr_debug("pointless warning\n"); 0909dc448c98ed NeilBrown 2009-07-01 5719 abort: 0909dc448c98ed NeilBrown 2009-07-01 5720 mutex_unlock(&disks_mutex); 00bcb4ac7ee7e5 NeilBrown 2010-06-01 5721 if (!error && mddev->kobj.sd) { 3830c62fef49f8 Greg Kroah-Hartman 2007-12-17 5722 kobject_uevent(&mddev->kobj, KOBJ_ADD); 00bcb4ac7ee7e5 NeilBrown 2010-06-01 5723 mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state"); e1a86dbbbd6a77 Junxiao Bi 2020-07-14 5724 mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level"); b62b75905d571c NeilBrown 2008-10-21 5725 } d3374825ce57ba NeilBrown 2009-01-09 5726 mddev_put(mddev); 0909dc448c98ed NeilBrown 2009-07-01 5727 return error; efeb53c0e57213 NeilBrown 2009-01-09 5728 } efeb53c0e57213 NeilBrown 2009-01-09 5729 :::::: The code at line 5705 was first introduced by commit :::::: b0140891a8cea36469f58d23859e599b1122bd37 md: Fix race when creating a new md device. :::::: TO: NeilBrown <neilb(a)suse.de&gt; :::::: CC: NeilBrown <neilb(a)suse.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org