====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kswapd0/78 is trying to acquire lock: ffff888042458610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279 but task is already holding lock: ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6973 [inline] ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x92a/0x2820 mm/vmscan.c:7352 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4301 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4315 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4904 [inline] slab_alloc_node mm/slub.c:5239 [inline] __kmalloc_cache_noprof+0x40/0x700 mm/slub.c:5771 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] btrfs_sysfs_add_qgroups+0xcd/0x2b0 fs/btrfs/sysfs.c:2693 btrfs_quota_enable+0x25b/0x2900 fs/btrfs/qgroup.c:1002 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776 btrfs_quota_enable+0x29d/0x2900 fs/btrfs/qgroup.c:1031 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1a4/0xd60 fs/btrfs/transaction.c:323 start_transaction+0x6b7/0x15f0 fs/btrfs/transaction.c:707 btrfs_rebuild_free_space_tree+0xad/0x6c0 fs/btrfs/free-space-tree.c:1330 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3052 open_ctree+0x2b11/0x3d20 fs/btrfs/disk-io.c:3603 btrfs_fill_super fs/btrfs/super.c:983 [inline] btrfs_get_tree_super fs/btrfs/super.c:1946 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline] btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123 vfs_get_tree+0x92/0x2a0 fs/super.c:1751 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3636 [inline] do_new_mount+0x302/0xa10 fs/namespace.c:3712 do_mount fs/namespace.c:4035 [inline] __do_sys_mount fs/namespace.c:4224 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4201 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: join_transaction+0x182/0xd60 fs/btrfs/transaction.c:322 start_transaction+0x6b7/0x15f0 fs/btrfs/transaction.c:707 btrfs_rebuild_free_space_tree+0xad/0x6c0 fs/btrfs/free-space-tree.c:1330 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3052 open_ctree+0x2b11/0x3d20 fs/btrfs/disk-io.c:3603 btrfs_fill_super fs/btrfs/super.c:983 [inline] btrfs_get_tree_super fs/btrfs/super.c:1946 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline] btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123 vfs_get_tree+0x92/0x2a0 fs/super.c:1751 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3636 [inline] do_new_mount+0x302/0xa10 fs/namespace.c:3712 do_mount fs/namespace.c:4035 [inline] __do_sys_mount fs/namespace.c:4224 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4201 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#2){.+.+}-{0:0}: 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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_intwrite include/linux/fs/super.h:177 [inline] start_transaction+0x56f/0x15f0 fs/btrfs/transaction.c:701 btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279 btrfs_evict_inode+0x94c/0x1050 fs/btrfs/inode.c:5564 evict+0x5f4/0xae0 fs/inode.c:837 __dentry_kill+0x209/0x660 fs/dcache.c:670 finish_dput+0xc9/0x480 fs/dcache.c:879 ovl_stack_put+0x6a/0xa0 fs/overlayfs/util.c:133 ovl_destroy_inode+0xaa/0x150 fs/overlayfs/super.c:218 destroy_inode fs/inode.c:396 [inline] evict+0x8aa/0xae0 fs/inode.c:861 __dentry_kill+0x209/0x660 fs/dcache.c:670 shrink_kill+0xa9/0x2c0 fs/dcache.c:1137 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1164 prune_dcache_sb+0x10e/0x180 fs/dcache.c:1246 super_cache_scan+0x369/0x4b0 fs/super.c:222 do_shrink_slab+0x6df/0x10d0 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628 shrink_one+0x2d9/0x720 mm/vmscan.c:4919 shrink_many mm/vmscan.c:4980 [inline] lru_gen_shrink_node mm/vmscan.c:5058 [inline] shrink_node+0x2f7d/0x35b0 mm/vmscan.c:6045 kswapd_shrink_node mm/vmscan.c:6899 [inline] balance_pgdat mm/vmscan.c:7082 [inline] kswapd+0x145a/0x2820 mm/vmscan.c:7352 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 other info that might help us debug this: Chain exists of: sb_internal#2 --> &fs_info->qgroup_ioctl_lock --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&fs_info->qgroup_ioctl_lock); lock(fs_reclaim); rlock(sb_internal#2); *** DEADLOCK *** 2 locks held by kswapd0/78: #0: ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6973 [inline] #0: ffffffff8e251780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x92a/0x2820 mm/vmscan.c:7352 #1: ffff88801236e0e0 (&type->s_umount_key#53){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:563 [inline] #1: ffff88801236e0e0 (&type->s_umount_key#53){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197 stack backtrace: CPU: 0 UID: 0 PID: 78 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_intwrite include/linux/fs/super.h:177 [inline] start_transaction+0x56f/0x15f0 fs/btrfs/transaction.c:701 btrfs_commit_inode_delayed_inode+0x117/0x2b0 fs/btrfs/delayed-inode.c:1279 btrfs_evict_inode+0x94c/0x1050 fs/btrfs/inode.c:5564 evict+0x5f4/0xae0 fs/inode.c:837 __dentry_kill+0x209/0x660 fs/dcache.c:670 finish_dput+0xc9/0x480 fs/dcache.c:879 ovl_stack_put+0x6a/0xa0 fs/overlayfs/util.c:133 ovl_destroy_inode+0xaa/0x150 fs/overlayfs/super.c:218 destroy_inode fs/inode.c:396 [inline] evict+0x8aa/0xae0 fs/inode.c:861 __dentry_kill+0x209/0x660 fs/dcache.c:670 shrink_kill+0xa9/0x2c0 fs/dcache.c:1137 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1164 prune_dcache_sb+0x10e/0x180 fs/dcache.c:1246 super_cache_scan+0x369/0x4b0 fs/super.c:222 do_shrink_slab+0x6df/0x10d0 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628 shrink_one+0x2d9/0x720 mm/vmscan.c:4919 shrink_many mm/vmscan.c:4980 [inline] lru_gen_shrink_node mm/vmscan.c:5058 [inline] shrink_node+0x2f7d/0x35b0 mm/vmscan.c:6045 kswapd_shrink_node mm/vmscan.c:6899 [inline] balance_pgdat mm/vmscan.c:7082 [inline] kswapd+0x145a/0x2820 mm/vmscan.c:7352 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246