====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 Not tainted ------------------------------------------------------ syz.0.2143/8649 is trying to acquire lock: ffff00000e163a20 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:191 but task is already holding lock: ffff0000144f6be8 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&q->q_usage_counter(io)#24){++++}-{0:0}: blk_alloc_queue+0x534/0x640 block/blk-core.c:461 blk_mq_alloc_queue+0x14c/0x22c block/blk-mq.c:4396 __blk_mq_alloc_disk+0x20/0x1a4 block/blk-mq.c:4443 loop_add+0x3bc/0x944 drivers/block/loop.c:2013 loop_init+0xd0/0x138 drivers/block/loop.c:2248 do_one_initcall+0x130/0x7f0 init/main.c:1274 do_initcall_level init/main.c:1336 [inline] do_initcalls init/main.c:1352 [inline] do_basic_setup init/main.c:1371 [inline] kernel_init_freeable+0x48c/0x6f4 init/main.c:1584 kernel_init+0x24/0x1dc init/main.c:1474 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 -> #2 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4045 [inline] fs_reclaim_acquire+0x138/0x160 mm/page_alloc.c:4059 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4099 [inline] slab_alloc_node mm/slub.c:4177 [inline] kmem_cache_alloc_noprof+0x5c/0x3b8 mm/slub.c:4204 __kernfs_iattrs+0xb4/0x30c fs/kernfs/inode.c:37 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x4c/0x2a0 fs/kernfs/inode.c:73 kernfs_iop_setattr+0xc0/0xf4 fs/kernfs/inode.c:127 notify_change+0x3cc/0xba8 fs/attr.c:552 do_truncate+0x174/0x1bc fs/open.c:68 handle_truncate fs/namei.c:3517 [inline] do_open fs/namei.c:3900 [inline] path_openat+0x17c4/0x24b0 fs/namei.c:4055 do_filp_open+0x184/0x360 fs/namei.c:4082 do_sys_openat2+0xe0/0x160 fs/open.c:1437 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __arm64_sys_openat+0x12c/0x1bc fs/open.c:1463 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #1 (iattr_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x144/0x9d8 kernel/locking/mutex.c:747 mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799 __kernfs_iattrs+0x38/0x30c fs/kernfs/inode.c:32 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr+0x4c/0x2a0 fs/kernfs/inode.c:73 kernfs_iop_setattr+0xc0/0xf4 fs/kernfs/inode.c:127 notify_change+0x3cc/0xba8 fs/attr.c:552 do_truncate+0x174/0x1bc fs/open.c:68 handle_truncate fs/namei.c:3517 [inline] do_open fs/namei.c:3900 [inline] path_openat+0x17c4/0x24b0 fs/namei.c:4055 do_filp_open+0x184/0x360 fs/namei.c:4082 do_sys_openat2+0xe0/0x160 fs/open.c:1437 do_sys_open fs/open.c:1452 [inline] __do_sys_openat fs/open.c:1468 [inline] __se_sys_openat fs/open.c:1463 [inline] __arm64_sys_openat+0x12c/0x1bc fs/open.c:1463 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x50/0x198 arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x10c/0x138 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 down_read+0xb4/0x314 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x1fc/0x374 fs/stat.c:213 vfs_getattr+0x40/0x54 fs/stat.c:262 loop_query_min_dio_size.isra.0+0xf8/0x1d0 drivers/block/loop.c:456 loop_assign_backing_file drivers/block/loop.c:509 [inline] loop_change_fd drivers/block/loop.c:587 [inline] lo_ioctl+0x13d0/0x1de8 drivers/block/loop.c:1516 lo_compat_ioctl+0x8c/0x1b4 drivers/block/loop.c:1673 compat_blkdev_ioctl+0x1f8/0x860 block/ioctl.c:760 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __arm64_compat_sys_ioctl+0x1d0/0x238 fs/ioctl.c:948 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc_compat+0x40/0x68 arch/arm64/kernel/syscall.c:157 el0_svc_compat+0x4c/0x17c arch/arm64/kernel/entry-common.c:911 el0t_32_sync_handler+0x98/0x13c arch/arm64/kernel/entry-common.c:921 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:605 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.0.2143/8649: #0: ffff000014743400 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable+0x2c/0xbc drivers/block/loop.c:118 #1: ffff0000144f6be8 (&q->q_usage_counter(io)#24){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 #2: ffff0000144f6c20 (&q->q_usage_counter(queue)#20){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:205 stack backtrace: CPU: 0 UID: 0 PID: 8649 Comm: syz.0.2143 Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xa4/0xf4 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x28c/0x370 kernel/locking/lockdep.c:2046 check_noncircular+0x168/0x17c kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1638/0x2380 kernel/locking/lockdep.c:5240 lock_acquire kernel/locking/lockdep.c:5871 [inline] lock_acquire+0x310/0x38c kernel/locking/lockdep.c:5828 down_read+0xb4/0x314 kernel/locking/rwsem.c:1524 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:191 vfs_getattr_nosec+0x1fc/0x374 fs/stat.c:213 vfs_getattr+0x40/0x54 fs/stat.c:262 loop_query_min_dio_size.isra.0+0xf8/0x1d0 drivers/block/loop.c:456 loop_assign_backing_file drivers/block/loop.c:509 [inline] loop_change_fd drivers/block/loop.c:587 [inline] lo_ioctl+0x13d0/0x1de8 drivers/block/loop.c:1516 lo_compat_ioctl+0x8c/0x1b4 drivers/block/loop.c:1673 compat_blkdev_ioctl+0x1f8/0x860 block/ioctl.c:760 __do_compat_sys_ioctl fs/ioctl.c:1005 [inline] __se_compat_sys_ioctl fs/ioctl.c:948 [inline] __arm64_compat_sys_ioctl+0x1d0/0x238 fs/ioctl.c:948 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:132 do_el0_svc_compat+0x40/0x68 arch/arm64/kernel/syscall.c:157 el0_svc_compat+0x4c/0x17c arch/arm64/kernel/entry-common.c:911 el0t_32_sync_handler+0x98/0x13c arch/arm64/kernel/entry-common.c:921 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:605