====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.576/8202 is trying to acquire lock: ffff88807d2a00e0 (&type->s_umount_key#31){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline] ffff88807d2a00e0 (&type->s_umount_key#31){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117 but task is already holding lock: ffff88801fe6c608 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: bdev_mark_dead+0x31/0x1a0 block/bdev.c:1011 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&bdev->bd_holder_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747 bd_finish_claiming+0x22f/0x3f0 block/bdev.c:568 blkdev_get_by_dev+0x45c/0x600 block/bdev.c:801 bdev_open_by_dev+0x77/0x100 block/bdev.c:842 setup_bdev_super+0x59/0x660 fs/super.c:1496 mount_bdev+0x1dd/0x2d0 fs/super.c:1640 legacy_get_tree+0xea/0x180 fs/fs_context.c:662 vfs_get_tree+0x8c/0x280 fs/super.c:1764 do_new_mount+0x24b/0xa40 fs/namespace.c:3377 init_mount+0xd2/0x120 fs/init.c:25 do_mount_root+0x97/0x230 init/do_mounts.c:166 mount_root_generic+0x195/0x3c0 init/do_mounts.c:205 prepare_namespace+0xc2/0x100 init/do_mounts.c:489 kernel_init_freeable+0x413/0x570 init/main.c:1566 kernel_init+0x1d/0x1c0 init/main.c:1443 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 -> #3 (bdev_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747 bd_prepare_to_claim+0x1ba/0x480 block/bdev.c:510 truncate_bdev_range+0x4e/0x260 block/bdev.c:105 blk_ioctl_discard block/ioctl.c:118 [inline] blkdev_common_ioctl+0x1efe/0x23d0 block/ioctl.c:509 blkdev_ioctl+0x4eb/0x6f0 block/ioctl.c:627 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #2 (mapping.invalidate_lock#2){++++}-{3:3}: down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520 filemap_invalidate_lock_shared include/linux/fs.h:859 [inline] page_cache_ra_unbounded+0xdc/0x770 mm/readahead.c:225 page_cache_sync_readahead include/linux/pagemap.h:1325 [inline] ext4_readdir+0xb71/0x39d0 fs/ext4/dir.c:197 iterate_dir+0x1c2/0x580 fs/readdir.c:106 __do_sys_getdents64 fs/readdir.c:405 [inline] __se_sys_getdents64+0xe9/0x260 fs/readdir.c:390 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (&type->i_mutex_dir_key#3){++++}-{3:3}: down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573 inode_lock include/linux/fs.h:804 [inline] ext4_process_orphan+0x187/0x300 fs/ext4/orphan.c:337 ext4_orphan_cleanup+0xbd4/0x1400 fs/ext4/orphan.c:474 __ext4_fill_super fs/ext4/super.c:5608 [inline] ext4_fill_super+0x5de7/0x66c0 fs/ext4/super.c:5731 get_tree_bdev+0x3e4/0x510 fs/super.c:1591 vfs_get_tree+0x8c/0x280 fs/super.c:1764 do_new_mount+0x24b/0xa40 fs/namespace.c:3377 do_mount fs/namespace.c:3717 [inline] __do_sys_mount fs/namespace.c:3926 [inline] __se_sys_mount+0x2da/0x3c0 fs/namespace.c:3903 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&type->s_umount_key#31){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520 __super_lock fs/super.c:58 [inline] super_lock+0x167/0x360 fs/super.c:117 super_lock_shared fs/super.c:146 [inline] super_lock_shared_active fs/super.c:1442 [inline] fs_bdev_mark_dead+0xad/0x1f0 fs/super.c:1458 bdev_mark_dead+0x83/0x1a0 block/bdev.c:1013 disk_force_media_change+0x132/0x1b0 block/disk-events.c:302 __loop_clr_fd+0x396/0x660 drivers/block/loop.c:1170 loop_clr_fd drivers/block/loop.c:1253 [inline] lo_ioctl+0x11e8/0x19f0 drivers/block/loop.c:1578 blkdev_ioctl+0x58b/0x6f0 block/ioctl.c:633 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: &type->s_umount_key#31 --> bdev_lock --> &bdev->bd_holder_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&bdev->bd_holder_lock); lock(bdev_lock); lock(&bdev->bd_holder_lock); rlock(&type->s_umount_key#31); *** DEADLOCK *** 1 lock held by syz.2.576/8202: #0: ffff88801fe6c608 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: bdev_mark_dead+0x31/0x1a0 block/bdev.c:1011 stack backtrace: CPU: 0 PID: 8202 Comm: syz.2.576 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520 __super_lock fs/super.c:58 [inline] super_lock+0x167/0x360 fs/super.c:117 super_lock_shared fs/super.c:146 [inline] super_lock_shared_active fs/super.c:1442 [inline] fs_bdev_mark_dead+0xad/0x1f0 fs/super.c:1458 bdev_mark_dead+0x83/0x1a0 block/bdev.c:1013 disk_force_media_change+0x132/0x1b0 block/disk-events.c:302 __loop_clr_fd+0x396/0x660 drivers/block/loop.c:1170 loop_clr_fd drivers/block/loop.c:1253 [inline] lo_ioctl+0x11e8/0x19f0 drivers/block/loop.c:1578 blkdev_ioctl+0x58b/0x6f0 block/ioctl.c:633 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb87d98e7ab Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00 RSP: 002b:00007fb87e829dc0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007fb87d98e7ab RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000006 RBP: 0000000000000010 R08: 0000000000000000 R09: 000000000000056b R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005 R13: 00007fb87e829ef0 R14: 00007fb87e82a668 R15: 00007fb8737f7000 loop2: detected capacity change from 0 to 512 EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback. ext4 filesystem being mounted at /168/bus supports timestamps until 2038-01-19 (0x7fffffff)