Hello, syzbot found the following issue on: HEAD commit: 27151f177827 Merge tag 'perf-tools-for-v5.15-2021-09-04' o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=104612b3300000 kernel config: https://syzkaller.appspot.com/x/.config?x=ac2f9cc43f6b17e4 dashboard link: https://syzkaller.appspot.com/bug?extid=f5608de5d89cc0d998c7 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f5608de5d89cc0d998c7@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 5.14.0-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/10219 is trying to acquire lock: ffff8880288d5918 (&disk->open_mutex){+.+.}-{3:3}, at: bd_register_pending_holders+0x2c/0x470 block/holder.c:160 but task is already holding lock: ffff8880996a0230 (&mddev->open_mutex){+.+.}-{3:3}, at: md_alloc+0x911/0x1150 drivers/md/md.c:5706 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 (&mddev->open_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 md_alloc+0x911/0x1150 drivers/md/md.c:5706 md_probe+0x69/0x70 drivers/md/md.c:5738 blk_request_module+0x111/0x1d0 block/genhd.c:632 blkdev_get_no_open+0x178/0x1e0 fs/block_dev.c:1150 blkdev_get_by_dev.part.0+0x22/0xb60 fs/block_dev.c:1214 blkdev_get_by_dev fs/block_dev.c:1323 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1329 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #7 (disks_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 md_alloc+0x37/0x1150 drivers/md/md.c:5644 md_probe+0x69/0x70 drivers/md/md.c:5738 blk_request_module+0x111/0x1d0 block/genhd.c:632 blkdev_get_no_open+0x178/0x1e0 fs/block_dev.c:1150 blkdev_get_by_dev.part.0+0x22/0xb60 fs/block_dev.c:1214 blkdev_get_by_dev fs/block_dev.c:1323 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1329 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #6 (major_names_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 blkdev_show+0x27/0x160 block/genhd.c:198 devinfo_show+0xc1/0xf0 fs/proc/devices.c:22 seq_read_iter+0xbb0/0x1240 fs/seq_file.c:272 proc_reg_read_iter+0x1fb/0x2d0 fs/proc/inode.c:300 call_read_iter include/linux/fs.h:2157 [inline] new_sync_read+0x421/0x6e0 fs/read_write.c:404 vfs_read+0x35c/0x600 fs/read_write.c:485 ksys_read+0x12d/0x250 fs/read_write.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #5 (&p->lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 seq_read_iter+0xdf/0x1240 fs/seq_file.c:182 call_read_iter include/linux/fs.h:2157 [inline] generic_file_splice_read+0x453/0x6d0 fs/splice.c:311 do_splice_to+0x1bf/0x250 fs/splice.c:796 splice_direct_to_actor+0x2c2/0x8c0 fs/splice.c:870 do_splice_direct+0x1b3/0x280 fs/splice.c:979 do_sendfile+0xae9/0x1240 fs/read_write.c:1249 __do_sys_sendfile64 fs/read_write.c:1314 [inline] __se_sys_sendfile64 fs/read_write.c:1300 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1300 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #4 (sb_writers#3){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1812 [inline] sb_start_write include/linux/fs.h:1882 [inline] file_start_write include/linux/fs.h:3008 [inline] lo_write_bvec+0x3b6/0x6d0 drivers/block/loop.c:327 lo_write_simple drivers/block/loop.c:350 [inline] do_req_filebacked drivers/block/loop.c:668 [inline] loop_handle_cmd drivers/block/loop.c:2202 [inline] loop_process_work+0xc60/0x24e0 drivers/block/loop.c:2242 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #3 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}: process_one_work+0x92e/0x16b0 kernel/workqueue.c:2273 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 -> #2 ((wq_completion)loop5){+.+.}-{0:0}: flush_workqueue+0x110/0x15b0 kernel/workqueue.c:2817 drain_workqueue+0x1a5/0x3c0 kernel/workqueue.c:2982 destroy_workqueue+0x71/0x800 kernel/workqueue.c:4419 __loop_clr_fd+0x212/0x15e0 drivers/block/loop.c:1368 lo_release+0x1ac/0x1f0 drivers/block/loop.c:2068 blkdev_put_whole fs/block_dev.c:1102 [inline] blkdev_put+0x2fb/0x9e0 fs/block_dev.c:1393 btrfs_close_bdev fs/btrfs/volumes.c:1108 [inline] btrfs_close_bdev fs/btrfs/volumes.c:1098 [inline] btrfs_close_one_device fs/btrfs/volumes.c:1127 [inline] close_fs_devices+0x26a/0xa20 fs/btrfs/volumes.c:1157 btrfs_close_devices+0x8e/0x4b0 fs/btrfs/volumes.c:1172 close_ctree+0x752/0x795 fs/btrfs/disk-io.c:4438 generic_shutdown_super+0x14c/0x370 fs/super.c:465 kill_anon_super+0x36/0x60 fs/super.c:1057 btrfs_kill_super+0x38/0x50 fs/btrfs/super.c:2348 deactivate_locked_super+0x94/0x160 fs/super.c:335 deactivate_super+0xad/0xd0 fs/super.c:366 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1137 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:209 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&lo->lo_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 lo_open+0x75/0x120 drivers/block/loop.c:2040 blkdev_get_whole+0x99/0x2a0 fs/block_dev.c:1079 blkdev_get_by_dev.part.0+0x354/0xb60 fs/block_dev.c:1234 blkdev_get_by_dev fs/block_dev.c:1323 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1329 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_open fs/open.c:1224 [inline] __se_sys_open fs/open.c:1220 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1220 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&disk->open_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 bd_register_pending_holders+0x2c/0x470 block/holder.c:160 device_add_disk+0x74c/0xfc0 block/genhd.c:470 add_disk include/linux/genhd.h:221 [inline] md_alloc+0x91d/0x1150 drivers/md/md.c:5707 md_probe+0x69/0x70 drivers/md/md.c:5738 blk_request_module+0x111/0x1d0 block/genhd.c:632 blkdev_get_no_open+0x178/0x1e0 fs/block_dev.c:1150 blkdev_get_by_dev.part.0+0x22/0xb60 fs/block_dev.c:1214 blkdev_get_by_dev fs/block_dev.c:1323 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1329 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: &disk->open_mutex --> disks_mutex --> &mddev->open_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mddev->open_mutex); lock(disks_mutex); lock(&mddev->open_mutex); lock(&disk->open_mutex); *** DEADLOCK *** 3 locks held by syz-executor.1/10219: #0: ffffffff8c204908 (major_names_lock){+.+.}-{3:3}, at: blk_request_module+0x25/0x1d0 block/genhd.c:629 #1: ffffffff8cd2fc48 (disks_mutex){+.+.}-{3:3}, at: md_alloc+0x37/0x1150 drivers/md/md.c:5644 #2: ffff8880996a0230 (&mddev->open_mutex){+.+.}-{3:3}, at: md_alloc+0x911/0x1150 drivers/md/md.c:5706 stack backtrace: CPU: 1 PID: 10219 Comm: syz-executor.1 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __mutex_lock_common kernel/locking/mutex.c:596 [inline] __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729 bd_register_pending_holders+0x2c/0x470 block/holder.c:160 device_add_disk+0x74c/0xfc0 block/genhd.c:470 add_disk include/linux/genhd.h:221 [inline] md_alloc+0x91d/0x1150 drivers/md/md.c:5707 md_probe+0x69/0x70 drivers/md/md.c:5738 blk_request_module+0x111/0x1d0 block/genhd.c:632 blkdev_get_no_open+0x178/0x1e0 fs/block_dev.c:1150 blkdev_get_by_dev.part.0+0x22/0xb60 fs/block_dev.c:1214 blkdev_get_by_dev fs/block_dev.c:1323 [inline] blkdev_open+0x295/0x300 fs/block_dev.c:1329 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3426 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3559 do_filp_open+0x1aa/0x400 fs/namei.c:3586 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f99121a3188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665f9 RDX: 0000000000000000 RSI: 00000000200020c0 RDI: ffffffffffffff9c RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 R13: 00007ffea339c34f R14: 00007f99121a3300 R15: 0000000000022000 --- This report is generated by a bot. 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