====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.9.455/7380 is trying to acquire lock: ffff0000c1928a10 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x98/0xe0 fs/kernfs/inode.c:190 but task is already holding lock: ffff0000c83989a8 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206 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+0x488/0x590 block/blk-core.c:504 blk_mq_alloc_queue+0x148/0x284 block/blk-mq.c:4431 __blk_mq_alloc_disk+0x38/0x10c block/blk-mq.c:4478 loop_add+0x358/0x8e4 drivers/block/loop.c:2073 loop_init+0xe8/0x10c drivers/block/loop.c:2312 do_one_initcall+0x274/0x9f8 init/main.c:1362 do_initcall_level+0x12c/0x1c4 init/main.c:1424 do_initcalls+0x70/0xd0 init/main.c:1440 do_basic_setup+0x7c/0x90 init/main.c:1460 kernel_init_freeable+0x258/0x398 init/main.c:1675 kernel_init+0x28/0x1e0 init/main.c:1565 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:854 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4375 [inline] fs_reclaim_acquire+0x90/0x110 mm/page_alloc.c:4389 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4636 [inline] slab_alloc_node mm/slub.c:4974 [inline] kmem_cache_alloc_noprof+0x60/0x5d4 mm/slub.c:5010 __kernfs_iattrs+0xd8/0x310 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x48/0x2ac fs/kernfs/inode.c:73 kernfs_iop_setattr+0xc4/0x11c fs/kernfs/inode.c:127 notify_change+0x928/0xb7c fs/attr.c:556 do_truncate+0x1a8/0x22c fs/open.c:68 handle_truncate fs/namei.c:4329 [inline] do_open fs/namei.c:4870 [inline] path_openat+0x1200/0x18f0 fs/namei.c:5029 do_file_open+0x1c8/0x2e8 fs/namei.c:5058 do_sys_openat2+0x114/0x1e8 fs/open.c:1417 do_sys_open+0xb0/0xe0 fs/open.c:1423 __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __arm64_sys_openat+0xa8/0xc4 fs/open.c:1434 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606 -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1660/0x2b08 kernel/locking/lockdep.c:5288 lock_acquire+0x13c/0x320 kernel/locking/lockdep.c:5942 down_read+0x58/0x2bc kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x98/0xe0 fs/kernfs/inode.c:190 vfs_getattr_nosec+0x250/0x388 fs/stat.c:213 vfs_getattr+0x60/0x88 fs/stat.c:262 loop_update_dio_alignment drivers/block/loop.c:465 [inline] loop_assign_backing_file+0x200/0x4b8 drivers/block/loop.c:526 loop_change_fd drivers/block/loop.c:606 [inline] lo_ioctl+0x1204/0x1740 drivers/block/loop.c:1569 blkdev_ioctl+0x574/0x904 block/ioctl.c:798 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x154/0x1cc fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606 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 *** locks held by syz.9.455/7380: 3, last CPU#0: #0: ffff0000c8581430 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable+0x64/0xbc drivers/block/loop.c:119 #1: ffff0000c83989a8 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206 #2: ffff0000c83989e0 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206 stack backtrace: CPU: 0 UID: 0 PID: 7380 Comm: syz.9.455 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x328/0x330 kernel/locking/lockdep.c:2087 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2219 check_prev_add kernel/locking/lockdep.c:3209 [inline] check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1660/0x2b08 kernel/locking/lockdep.c:5288 lock_acquire+0x13c/0x320 kernel/locking/lockdep.c:5942 down_read+0x58/0x2bc kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x98/0xe0 fs/kernfs/inode.c:190 vfs_getattr_nosec+0x250/0x388 fs/stat.c:213 vfs_getattr+0x60/0x88 fs/stat.c:262 loop_update_dio_alignment drivers/block/loop.c:465 [inline] loop_assign_backing_file+0x200/0x4b8 drivers/block/loop.c:526 loop_change_fd drivers/block/loop.c:606 [inline] lo_ioctl+0x1204/0x1740 drivers/block/loop.c:1569 blkdev_ioctl+0x574/0x904 block/ioctl.c:798 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x154/0x1cc fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606