====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc4-syzkaller-00051-g7a13c14ee59d #0 Not tainted ------------------------------------------------------ syz.3.402/7500 is trying to acquire lock: ffff88801c68e1e0 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x9c/0xf0 fs/kernfs/inode.c:191 but task is already holding lock: ffff88810706b168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:215 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}: blk_alloc_queue+0x619/0x760 block/blk-core.c:461 blk_mq_alloc_queue+0x179/0x290 block/blk-mq.c:4348 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4395 loop_add+0x496/0xb70 drivers/block/loop.c:1990 loop_init+0x164/0x270 drivers/block/loop.c:2225 do_one_initcall+0x120/0x6e0 init/main.c:1257 do_initcall_level init/main.c:1319 [inline] do_initcalls init/main.c:1335 [inline] do_basic_setup init/main.c:1354 [inline] kernel_init_freeable+0x5c2/0x900 init/main.c:1567 kernel_init+0x1c/0x2b0 init/main.c:1457 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4064 [inline] fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4078 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4112 [inline] slab_alloc_node mm/slub.c:4190 [inline] kmem_cache_alloc_noprof+0x53/0x3b0 mm/slub.c:4217 __kernfs_iattrs+0xbc/0x3f0 fs/kernfs/inode.c:37 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x4d/0x3c0 fs/kernfs/inode.c:73 kernfs_iop_setattr+0xda/0x120 fs/kernfs/inode.c:127 notify_change+0x6a6/0x1230 fs/attr.c:552 do_truncate+0x15b/0x220 fs/open.c:65 handle_truncate fs/namei.c:3501 [inline] do_open fs/namei.c:3884 [inline] path_openat+0x2761/0x2d40 fs/namei.c:4039 do_filp_open+0x20b/0x470 fs/namei.c:4066 do_sys_openat2+0x11b/0x1d0 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+0x174/0x210 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 ( iattr_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 __kernfs_iattrs+0x2b/0x3f0 fs/kernfs/inode.c:32 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x4d/0x3c0 fs/kernfs/inode.c:73 kernfs_iop_setattr+0xda/0x120 fs/kernfs/inode.c:127 notify_change+0x6a6/0x1230 fs/attr.c:552 do_truncate+0x15b/0x220 fs/open.c:65 handle_truncate fs/namei.c:3501 [inline] do_open fs/namei.c:3884 [inline] path_openat+0x2761/0x2d40 fs/namei.c:4039 do_filp_open+0x20b/0x470 fs/namei.c:4066 do_sys_openat2+0x11b/0x1d0 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+0x174/0x210 fs/open.c:1455 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 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 kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read+0x9b/0x480 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0x9c/0xf0 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x2a9/0x430 fs/stat.c:210 vfs_getattr+0x4a/0x60 fs/stat.c:259 loop_query_min_dio_size.isra.0+0x120/0x260 drivers/block/loop.c:452 loop_assign_backing_file drivers/block/loop.c:505 [inline] loop_change_fd drivers/block/loop.c:568 [inline] lo_ioctl+0x1d33/0x27e0 drivers/block/loop.c:1493 blkdev_ioctl+0x274/0x6d0 block/ioctl.c:704 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 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.3.402/7500: #0: ffff888025c76b68 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:118 [inline] #0: ffff888025c76b68 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_change_fd drivers/block/loop.c:533 [inline] #0: ffff888025c76b68 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_ioctl+0x2a9/0x27e0 drivers/block/loop.c:1493 #1: ffff88810706b168 (&q->q_usage_counter(io)#19){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:215 #2: ffff88810706b1a0 (&q->q_usage_counter(queue)#20){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x15/0x20 block/blk-mq.c:215 stack backtrace: CPU: 3 UID: 0 PID: 7500 Comm: syz.3.402 Not tainted 6.15.0-rc4-syzkaller-00051-g7a13c14ee59d #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2079 check_noncircular+0x14c/0x170 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 kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read+0x9b/0x480 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0x9c/0xf0 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x2a9/0x430 fs/stat.c:210 vfs_getattr+0x4a/0x60 fs/stat.c:259 loop_query_min_dio_size.isra.0+0x120/0x260 drivers/block/loop.c:452 loop_assign_backing_file drivers/block/loop.c:505 [inline] loop_change_fd drivers/block/loop.c:568 [inline] lo_ioctl+0x1d33/0x27e0 drivers/block/loop.c:1493 blkdev_ioctl+0x274/0x6d0 block/ioctl.c:704 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f30ab98e969 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:00007f30ac757038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f30abbb5fa0 RCX: 00007f30ab98e969 RDX: 0000000000000004 RSI: 0000000000004c06 RDI: 0000000000000003 RBP: 00007f30aba10ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f30abbb5fa0 R15: 00007ffcdcb30248