====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.2.1563/10328 is trying to acquire lock: ffff0000c1919210 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x94/0xdc fs/kernfs/inode.c:192 but task is already holding lock: ffff0000c7d96fc0 (&q->q_usage_counter(io)#24){++++}-{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)#24){++++}-{0:0}: blk_alloc_queue+0x47c/0x57c block/blk-core.c:461 blk_mq_alloc_queue+0x148/0x294 block/blk-mq.c:4450 __blk_mq_alloc_disk+0x38/0x10c block/blk-mq.c:4497 loop_add+0x34c/0x8b8 drivers/block/loop.c:2049 loop_init+0xe8/0x10c drivers/block/loop.c:2288 do_one_initcall+0x274/0xc20 init/main.c:1392 do_initcall_level+0x128/0x1c4 init/main.c:1454 do_initcalls+0x70/0xd0 init/main.c:1470 do_basic_setup+0x7c/0x90 init/main.c:1490 kernel_init_freeable+0x268/0x3a8 init/main.c:1703 kernel_init+0x24/0x1dc init/main.c:1593 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4325 [inline] fs_reclaim_acquire+0x8c/0x118 mm/page_alloc.c:4339 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] kmem_cache_alloc_noprof+0x58/0x558 mm/slub.c:4905 __kernfs_iattrs+0xd8/0x2d8 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:59 [inline] __kernfs_setattr+0x4c/0x2c4 fs/kernfs/inode.c:72 kernfs_iop_setattr+0xc4/0x11c fs/kernfs/inode.c:126 notify_change+0x984/0xbd8 fs/attr.c:556 do_truncate+0x1a8/0x22c fs/open.c:68 handle_truncate fs/namei.c:4307 [inline] do_open fs/namei.c:4703 [inline] path_openat+0x23a4/0x2a6c fs/namei.c:4858 do_file_open+0x1c4/0x2e4 fs/namei.c:4887 do_sys_openat2+0x114/0x1e8 fs/open.c:1364 do_sys_open+0xac/0xdc fs/open.c:1370 __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __arm64_sys_openat+0x9c/0xb8 fs/open.c:1381 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x25c arch/arm64/kernel/entry-common.c:723 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:742 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 down_read+0x58/0x2bc kernel/locking/rwsem.c:1568 kernfs_iop_getattr+0x94/0xdc fs/kernfs/inode.c:192 vfs_getattr_nosec+0x254/0x38c fs/stat.c:213 vfs_getattr+0x60/0x88 fs/stat.c:262 loop_query_min_dio_size drivers/block/loop.c:463 [inline] loop_assign_backing_file+0x200/0x3cc drivers/block/loop.c:516 loop_change_fd drivers/block/loop.c:596 [inline] lo_ioctl+0x1158/0x1684 drivers/block/loop.c:1545 blkdev_ioctl+0x574/0x904 block/ioctl.c:797 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+0x14c/0x1c4 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+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x25c arch/arm64/kernel/entry-common.c:723 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:742 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 other info that might help us debug this: Chain exists of: &root->kernfs_iattr_rwsem --> fs_reclaim --> &q->q_usage_counter(io)#24 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#24); lock(fs_reclaim); lock(&q->q_usage_counter(io)#24); rlock(&root->kernfs_iattr_rwsem); *** DEADLOCK *** 3 locks held by syz.2.1563/10328: #0: ffff0000c8074430 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable+0x64/0xbc drivers/block/loop.c:118 #1: ffff0000c7d96fc0 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206 #2: ffff0000c7d96ff8 (&q->q_usage_counter(queue)#8){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x20/0x38 block/blk-mq.c:206 stack backtrace: CPU: 0 UID: 0 PID: 10328 Comm: syz.2.1563 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 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:2043 check_noncircular+0x158/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1780/0x2f44 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x368 kernel/locking/lockdep.c:5868 down_read+0x58/0x2bc kernel/locking/rwsem.c:1568 kernfs_iop_getattr+0x94/0xdc fs/kernfs/inode.c:192 vfs_getattr_nosec+0x254/0x38c fs/stat.c:213 vfs_getattr+0x60/0x88 fs/stat.c:262 loop_query_min_dio_size drivers/block/loop.c:463 [inline] loop_assign_backing_file+0x200/0x3cc drivers/block/loop.c:516 loop_change_fd drivers/block/loop.c:596 [inline] lo_ioctl+0x1158/0x1684 drivers/block/loop.c:1545 blkdev_ioctl+0x574/0x904 block/ioctl.c:797 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+0x14c/0x1c4 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+0xe8/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x25c arch/arm64/kernel/entry-common.c:723 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:742 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594