====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc5-syzkaller-00032-g0d8d44db295c #0 Not tainted ------------------------------------------------------ syz.5.2151/15075 is trying to acquire lock: ffff88801aef79e0 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0xb3/0x500 fs/kernfs/inode.c:191 but task is already holding lock: ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:928 [inline] ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:566 [inline] ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: lo_ioctl+0x1c22/0x22e0 drivers/block/loop.c:1493 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&q->q_usage_counter(io)#19){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 blk_alloc_queue+0x538/0x620 block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4348 [inline] __blk_mq_alloc_disk+0x164/0x350 block/blk-mq.c:4395 loop_add+0x41d/0xae0 drivers/block/loop.c:1990 loop_init+0x173/0x230 drivers/block/loop.c:2225 do_one_initcall+0x233/0x820 init/main.c:1257 do_initcall_level+0x137/0x1f0 init/main.c:1319 do_initcalls+0x69/0xd0 init/main.c:1335 kernel_init_freeable+0x3d9/0x570 init/main.c:1567 kernel_init+0x1d/0x1d0 init/main.c:1457 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __fs_reclaim_acquire mm/page_alloc.c:4064 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4078 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4098 [inline] slab_alloc_node mm/slub.c:4176 [inline] kmem_cache_alloc_noprof+0x44/0x3c0 mm/slub.c:4203 __kernfs_iattrs+0x93/0x280 fs/kernfs/inode.c:37 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr fs/kernfs/inode.c:73 [inline] kernfs_iop_setattr+0xea/0x3f0 fs/kernfs/inode.c:127 notify_change+0xb33/0xe40 fs/attr.c:552 do_truncate+0x19a/0x220 fs/open.c:65 handle_truncate fs/namei.c:3501 [inline] do_open fs/namei.c:3884 [inline] path_openat+0x306c/0x3830 fs/namei.c:4039 do_filp_open+0x1fa/0x410 fs/namei.c:4066 do_sys_openat2+0x121/0x1c0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (iattr_mutex){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746 __kernfs_iattrs+0x2a/0x280 fs/kernfs/inode.c:32 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr fs/kernfs/inode.c:73 [inline] kernfs_iop_setattr+0xea/0x3f0 fs/kernfs/inode.c:127 notify_change+0xb33/0xe40 fs/attr.c:552 do_truncate+0x19a/0x220 fs/open.c:65 handle_truncate fs/namei.c:3501 [inline] do_open fs/namei.c:3884 [inline] path_openat+0x306c/0x3830 fs/namei.c:4039 do_filp_open+0x1fa/0x410 fs/namei.c:4066 do_sys_openat2+0x121/0x1c0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_openat fs/open.c:1460 [inline] __se_sys_openat fs/open.c:1455 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0xb3/0x500 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x2de/0x430 fs/stat.c:210 loop_query_min_dio_size drivers/block/loop.c:452 [inline] loop_assign_backing_file+0x227/0x410 drivers/block/loop.c:505 loop_change_fd drivers/block/loop.c:568 [inline] lo_ioctl+0x1c94/0x22e0 drivers/block/loop.c:1493 blkdev_ioctl+0x5a5/0x6d0 block/ioctl.c:704 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &root->kernfs_iattr_rwsem --> fs_reclaim --> &q->q_usage_counter(io)#19 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#19); lock(fs_reclaim); lock(&q->q_usage_counter(io)#19); rlock(&root->kernfs_iattr_rwsem); *** DEADLOCK *** 3 locks held by syz.5.2151/15075: #0: ffff888024b16b68 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:118 [inline] #0: ffff888024b16b68 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_change_fd drivers/block/loop.c:533 [inline] #0: ffff888024b16b68 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_ioctl+0xef0/0x22e0 drivers/block/loop.c:1493 #1: ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:928 [inline] #1: ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:566 [inline] #1: ffff888024b03168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: lo_ioctl+0x1c22/0x22e0 drivers/block/loop.c:1493 #2: ffff888024b031a0 (&q->q_usage_counter(queue)#19){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:928 [inline] #2: ffff888024b031a0 (&q->q_usage_counter(queue)#19){+.+.}-{0:0}, at: loop_change_fd drivers/block/loop.c:566 [inline] #2: ffff888024b031a0 (&q->q_usage_counter(queue)#19){+.+.}-{0:0}, at: lo_ioctl+0x1c22/0x22e0 drivers/block/loop.c:1493 stack backtrace: CPU: 0 UID: 0 PID: 15075 Comm: syz.5.2151 Not tainted 6.15.0-rc5-syzkaller-00032-g0d8d44db295c #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0xb3/0x500 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x2de/0x430 fs/stat.c:210 loop_query_min_dio_size drivers/block/loop.c:452 [inline] loop_assign_backing_file+0x227/0x410 drivers/block/loop.c:505 loop_change_fd drivers/block/loop.c:568 [inline] lo_ioctl+0x1c94/0x22e0 drivers/block/loop.c:1493 blkdev_ioctl+0x5a5/0x6d0 block/ioctl.c:704 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3c0178e969 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3c0257b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3c019b6080 RCX: 00007f3c0178e969 RDX: 0000000000000007 RSI: 0000000000004c06 RDI: 0000000000000003 RBP: 00007f3c01810ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3c019b6080 R15: 00007f3c01adfa28