====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.3083/12595 is trying to acquire lock: ffff00000e651220 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:193 but task is already holding lock: ffff000014b8cc60 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 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}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x3f0/0x46c kernel/locking/lockdep.c:5825 blk_alloc_queue+0x4e0/0x640 block/blk-core.c:461 blk_mq_alloc_queue+0x148/0x224 block/blk-mq.c:4429 __blk_mq_alloc_disk+0x20/0x120 block/blk-mq.c:4476 loop_add+0x3ac/0x96c drivers/block/loop.c:2049 loop_init+0x108/0x12c drivers/block/loop.c:2288 do_one_initcall+0x134/0xb40 init/main.c:1382 do_initcall_level init/main.c:1444 [inline] do_initcalls init/main.c:1460 [inline] do_basic_setup init/main.c:1479 [inline] kernel_init_freeable+0x5e8/0x66c init/main.c:1692 kernel_init+0x24/0x150 init/main.c:1582 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x3f0/0x46c kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0x138/0x160 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4489 [inline] slab_alloc_node mm/slub.c:4843 [inline] kmem_cache_alloc_noprof+0x64/0x664 mm/slub.c:4873 __kernfs_iattrs+0x114/0x340 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:61 [inline] __kernfs_setattr+0x4c/0x2a0 fs/kernfs/inode.c:74 kernfs_iop_setattr+0xc0/0x100 fs/kernfs/inode.c:128 notify_change+0x6e8/0xbe8 fs/attr.c:556 do_truncate+0x188/0x1dc fs/open.c:68 handle_truncate fs/namei.c:4285 [inline] do_open fs/namei.c:4681 [inline] path_openat+0x1a18/0x2654 fs/namei.c:4836 do_file_open+0x18c/0x37c fs/namei.c:4865 do_sys_openat2+0xdc/0x184 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __arm64_sys_openat+0x130/0x1d0 fs/open.c:1383 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x70/0x260 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+0x54/0x29c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add+0x114/0xca0 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x13f4/0x1a5c kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x3f0/0x46c kernel/locking/lockdep.c:5825 down_read+0xb8/0x320 kernel/locking/rwsem.c:1537 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:193 vfs_getattr_nosec+0x220/0x380 fs/stat.c:213 vfs_getattr+0x40/0x60 fs/stat.c:262 loop_query_min_dio_size.isra.0+0xfc/0x1d8 drivers/block/loop.c:463 loop_assign_backing_file drivers/block/loop.c:516 [inline] loop_change_fd drivers/block/loop.c:596 [inline] lo_ioctl+0xe5c/0x1760 drivers/block/loop.c:1545 blkdev_ioctl+0x3bc/0x7f0 block/ioctl.c:804 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+0x124/0x1a4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x70/0x260 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+0x54/0x29c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743 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)#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.3.3083/12595: #0: ffff000014c36448 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable+0x28/0xb8 drivers/block/loop.c:118 #1: ffff000014b8cc60 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:206 #2: ffff000014b8cc98 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:206 stack backtrace: CPU: 0 UID: 0 PID: 12595 Comm: syz.3.3083 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x7c/0xb0 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x23c/0x284 kernel/locking/lockdep.c:2043 check_noncircular+0x174/0x194 kernel/locking/lockdep.c:2175 check_prev_add+0x114/0xca0 kernel/locking/lockdep.c:3165 check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x13f4/0x1a5c kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x3f0/0x46c kernel/locking/lockdep.c:5825 down_read+0xb8/0x320 kernel/locking/rwsem.c:1537 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:193 vfs_getattr_nosec+0x220/0x380 fs/stat.c:213 vfs_getattr+0x40/0x60 fs/stat.c:262 loop_query_min_dio_size.isra.0+0xfc/0x1d8 drivers/block/loop.c:463 loop_assign_backing_file drivers/block/loop.c:516 [inline] loop_change_fd drivers/block/loop.c:596 [inline] lo_ioctl+0xe5c/0x1760 drivers/block/loop.c:1545 blkdev_ioctl+0x3bc/0x7f0 block/ioctl.c:804 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+0x124/0x1a4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x70/0x260 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+0x54/0x29c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596