====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.4.4161/20386 is trying to acquire lock: ffff88801aeaf2c0 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 but task is already holding lock: ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:609 [inline] ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: lo_ioctl+0x1a7d/0x1fe0 drivers/block/loop.c:1560 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#22){++++}-{0:0}: blk_alloc_queue+0x54c/0x690 block/blk-core.c:504 blk_mq_alloc_queue block/blk-mq.c:4420 [inline] __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4467 loop_add+0x480/0xb50 drivers/block/loop.c:2128 loop_init+0xd7/0x160 drivers/block/loop.c:2367 do_one_initcall+0x250/0x870 init/main.c:1353 do_initcall_level+0x10a/0x1a0 init/main.c:1415 do_initcalls+0x59/0xa0 init/main.c:1431 kernel_init_freeable+0x29d/0x3e0 init/main.c:1666 kernel_init+0x22/0x1d0 init/main.c:1556 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4329 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4559 [inline] slab_alloc_node mm/slub.c:4897 [inline] kmem_cache_alloc_noprof+0x5c/0x680 mm/slub.c:4933 __kernfs_iattrs+0xdd/0x380 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr fs/kernfs/inode.c:73 [inline] kernfs_iop_setattr+0xe6/0x3f0 fs/kernfs/inode.c:127 notify_change+0xbb8/0xec0 fs/attr.c:556 do_truncate+0x1c2/0x250 fs/open.c:68 handle_truncate fs/namei.c:4300 [inline] do_open fs/namei.c:4698 [inline] path_openat+0x300d/0x3850 fs/namei.c:4857 do_file_open+0x23e/0x4a0 fs/namei.c:4886 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 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:3167 [inline] check_prevs_add kernel/locking/lockdep.c:3286 [inline] validate_chain kernel/locking/lockdep.c:3910 [inline] __lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5240 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5892 down_read+0x97/0x200 kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 vfs_getattr_nosec+0x2e1/0x430 fs/stat.c:213 loop_query_min_dio_size drivers/block/loop.c:478 [inline] loop_assign_backing_file+0x286/0x4c0 drivers/block/loop.c:531 loop_change_fd drivers/block/loop.c:611 [inline] lo_ioctl+0x1af1/0x1fe0 drivers/block/loop.c:1560 blkdev_ioctl+0x5e6/0x750 block/ioctl.c:797 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 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)#22 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#22); lock(fs_reclaim); lock(&q->q_usage_counter(io)#22); rlock(&root->kernfs_iattr_rwsem); *** DEADLOCK *** 3 locks held by syz.4.4161/20386: #0: ffff888027605498 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:137 [inline] #0: ffff888027605498 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_change_fd drivers/block/loop.c:576 [inline] #0: ffff888027605498 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_ioctl+0x14d8/0x1fe0 drivers/block/loop.c:1560 #1: ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] #1: ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:609 [inline] #1: ffff88802749a8c0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: lo_ioctl+0x1a7d/0x1fe0 drivers/block/loop.c:1560 #2: ffff88802749a8f8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] #2: ffff88802749a8f8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: loop_change_fd drivers/block/loop.c:609 [inline] #2: ffff88802749a8f8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: lo_ioctl+0x1a7d/0x1fe0 drivers/block/loop.c:1560 stack backtrace: CPU: 1 UID: 0 PID: 20386 Comm: syz.4.4161 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2045 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2177 check_prev_add kernel/locking/lockdep.c:3167 [inline] check_prevs_add kernel/locking/lockdep.c:3286 [inline] validate_chain kernel/locking/lockdep.c:3910 [inline] __lock_acquire+0x15ff/0x2e40 kernel/locking/lockdep.c:5240 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5892 down_read+0x97/0x200 kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 vfs_getattr_nosec+0x2e1/0x430 fs/stat.c:213 loop_query_min_dio_size drivers/block/loop.c:478 [inline] loop_assign_backing_file+0x286/0x4c0 drivers/block/loop.c:531 loop_change_fd drivers/block/loop.c:611 [inline] lo_ioctl+0x1af1/0x1fe0 drivers/block/loop.c:1560 blkdev_ioctl+0x5e6/0x750 block/ioctl.c:797 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f569befde59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f569a114028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f569c186180 RCX: 00007f569befde59 RDX: 000000000000000e RSI: 0000000000004c06 RDI: 0000000000000003 RBP: 00007f569bf93e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f569c186218 R14: 00007f569c186180 R15: 00007ffdfe00dfc8 Dev loop5: unable to read RDB block 7 loop5: unable to read partition table loop5: partition table beyond EOD, truncated loop_reread_partitions: partition scan of loop5 (Wk݊5) failed (rc=-5)