====================================================== WARNING: possible circular locking dependency detected 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 Not tainted ------------------------------------------------------ syz.2.138/7030 is trying to acquire lock: ffff0000c18a3a20 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0xa0/0x410 fs/kernfs/inode.c:193 but task is already holding lock: ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:934 [inline] ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:584 [inline] ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: lo_ioctl+0x1130/0x16b0 drivers/block/loop.c:1534 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+0x48c/0x54c block/blk-core.c:461 blk_mq_alloc_queue block/blk-mq.c:4400 [inline] __blk_mq_alloc_disk+0x124/0x304 block/blk-mq.c:4447 loop_add+0x324/0x880 drivers/block/loop.c:2034 loop_init+0xe8/0x10c drivers/block/loop.c:2269 do_one_initcall+0x250/0x990 init/main.c:1269 do_initcall_level+0x128/0x1c4 init/main.c:1331 do_initcalls+0x70/0xd0 init/main.c:1347 do_basic_setup+0x78/0x8c init/main.c:1366 kernel_init_freeable+0x268/0x39c init/main.c:1579 kernel_init+0x24/0x1dc init/main.c:1469 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4234 [inline] fs_reclaim_acquire+0x8c/0x118 mm/page_alloc.c:4248 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4131 [inline] slab_alloc_node mm/slub.c:4209 [inline] kmem_cache_alloc_noprof+0x58/0x3e8 mm/slub.c:4236 __kernfs_iattrs+0xd4/0x2d8 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:61 [inline] __kernfs_setattr fs/kernfs/inode.c:74 [inline] kernfs_iop_setattr+0xdc/0x374 fs/kernfs/inode.c:128 notify_change+0x9a4/0xc50 fs/attr.c:552 do_truncate+0x198/0x210 fs/open.c:68 handle_truncate fs/namei.c:3508 [inline] do_open fs/namei.c:3891 [inline] path_openat+0x25a0/0x2c40 fs/namei.c:4046 do_filp_open+0x18c/0x36c fs/namei.c:4073 do_sys_openat2+0x11c/0x1b4 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __arm64_sys_openat+0x120/0x158 fs/open.c:1461 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #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+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 down_read+0x58/0x2f8 kernel/locking/rwsem.c:1537 kernfs_iop_getattr+0xa0/0x410 fs/kernfs/inode.c:193 vfs_getattr_nosec+0x254/0x38c fs/stat.c:213 vfs_getattr+0x60/0x84 fs/stat.c:262 loop_query_min_dio_size drivers/block/loop.c:455 [inline] loop_assign_backing_file+0x1d8/0x390 drivers/block/loop.c:508 loop_change_fd drivers/block/loop.c:586 [inline] lo_ioctl+0x1184/0x16b0 drivers/block/loop.c:1534 blkdev_ioctl+0x610/0xac0 block/ioctl.c:705 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 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.2.138/7030: #0: ffff0000c9fc9400 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:118 [inline] #0: ffff0000c9fc9400 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_change_fd drivers/block/loop.c:551 [inline] #0: ffff0000c9fc9400 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_ioctl+0xc78/0x16b0 drivers/block/loop.c:1534 #1: ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:934 [inline] #1: ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:584 [inline] #1: ffff0000c9e2e278 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: lo_ioctl+0x1130/0x16b0 drivers/block/loop.c:1534 #2: ffff0000c9e2e2b0 (&q->q_usage_counter(queue)#22){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:934 [inline] #2: ffff0000c9e2e2b0 (&q->q_usage_counter(queue)#22){+.+.}-{0:0}, at: loop_change_fd drivers/block/loop.c:584 [inline] #2: ffff0000c9e2e2b0 (&q->q_usage_counter(queue)#22){+.+.}-{0:0}, at: lo_ioctl+0x1130/0x16b0 drivers/block/loop.c:1534 stack backtrace: CPU: 1 UID: 0 PID: 7030 Comm: syz.2.138 Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 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+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 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+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 down_read+0x58/0x2f8 kernel/locking/rwsem.c:1537 kernfs_iop_getattr+0xa0/0x410 fs/kernfs/inode.c:193 vfs_getattr_nosec+0x254/0x38c fs/stat.c:213 vfs_getattr+0x60/0x84 fs/stat.c:262 loop_query_min_dio_size drivers/block/loop.c:455 [inline] loop_assign_backing_file+0x1d8/0x390 drivers/block/loop.c:508 loop_change_fd drivers/block/loop.c:586 [inline] lo_ioctl+0x1184/0x16b0 drivers/block/loop.c:1534 blkdev_ioctl+0x610/0xac0 block/ioctl.c:705 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl fs/ioctl.c:584 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:584 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596