====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.6.1684/9364 is trying to acquire lock: ffff00000e660a10 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:192 but task is already holding lock: ffff000014c4c158 (&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+0x3ac/0x440 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:4450 __blk_mq_alloc_disk+0x20/0x120 block/blk-mq.c:4497 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:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x5ec/0x670 init/main.c:1703 kernel_init+0x24/0x150 init/main.c:1593 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:858 -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x3ac/0x440 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4325 [inline] fs_reclaim_acquire+0x138/0x160 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+0x64/0x6c4 mm/slub.c:4905 __kernfs_iattrs+0x114/0x330 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:59 [inline] __kernfs_setattr+0x4c/0x2a0 fs/kernfs/inode.c:72 kernfs_iop_setattr+0xc0/0x100 fs/kernfs/inode.c:126 notify_change+0x6e8/0xbe8 fs/attr.c:556 do_truncate+0x188/0x1dc fs/open.c:68 handle_truncate fs/namei.c:4307 [inline] do_open fs/namei.c:4703 [inline] path_openat+0x1a18/0x2654 fs/namei.c:4858 do_file_open+0x18c/0x37c fs/namei.c:4887 do_sys_openat2+0xdc/0x184 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __arm64_sys_openat+0x130/0x1d0 fs/open.c:1381 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x74/0x240 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:121 do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:140 el0_svc+0x58/0x2a4 arch/arm64/kernel/entry-common.c:723 el0t_64_sync_handler+0xa0/0xe4 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+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+0x3ac/0x440 kernel/locking/lockdep.c:5825 down_read+0xb8/0x318 kernel/locking/rwsem.c:1568 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:192 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 lo_compat_ioctl+0xc8/0x1c0 drivers/block/loop.c:1705 compat_blkdev_ioctl+0x5f4/0x850 block/ioctl.c:853 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __arm64_compat_sys_ioctl+0x1a8/0x21c fs/ioctl.c:638 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x74/0x240 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:121 do_el0_svc_compat+0x40/0x58 arch/arm64/kernel/syscall.c:146 el0_svc_compat+0x54/0x270 arch/arm64/kernel/entry-common.c:874 el0t_32_sync_handler+0x88/0xac arch/arm64/kernel/entry-common.c:892 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:599 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.6.1684/9364: #0: ffff000014ca1430 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable+0x28/0xb8 drivers/block/loop.c:118 #1: ffff000014c4c158 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:206 #2: ffff000014c4c190 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x18/0x30 block/blk-mq.c:206 stack backtrace: CPU: 1 UID: 0 PID: 9364 Comm: syz.6.1684 Not tainted syzkaller #0 PREEMPT 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+0x3ac/0x440 kernel/locking/lockdep.c:5825 down_read+0xb8/0x318 kernel/locking/rwsem.c:1568 kernfs_iop_getattr+0x88/0xf0 fs/kernfs/inode.c:192 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 lo_compat_ioctl+0xc8/0x1c0 drivers/block/loop.c:1705 compat_blkdev_ioctl+0x5f4/0x850 block/ioctl.c:853 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __arm64_compat_sys_ioctl+0x1a8/0x21c fs/ioctl.c:638 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x74/0x240 arch/arm64/kernel/syscall.c:49 el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:121 do_el0_svc_compat+0x40/0x58 arch/arm64/kernel/syscall.c:146 el0_svc_compat+0x54/0x270 arch/arm64/kernel/entry-common.c:874 el0t_32_sync_handler+0x88/0xac arch/arm64/kernel/entry-common.c:892 el0t_32_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:599