====================================================== WARNING: possible circular locking dependency detected 4.19.0-rc6+ #42 Not tainted ------------------------------------------------------ kswapd0/1375 is trying to acquire lock: 0000000090e0cdd3 (jbd2_handle){++++}, at: start_this_handle+0x581/0x1250 fs/jbd2/transaction.c:383 but task is already holding lock: 00000000f22b8da2 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:4539 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (fs_reclaim){+.+.}: __fs_reclaim_acquire mm/page_alloc.c:3728 [inline] fs_reclaim_acquire.part.97+0x24/0x30 mm/page_alloc.c:3739 fs_reclaim_acquire+0x14/0x20 mm/page_alloc.c:3740 slab_pre_alloc_hook mm/slab.h:418 [inline] slab_alloc mm/slab.c:3378 [inline] kmem_cache_alloc_trace+0x2d/0x750 mm/slab.c:3618 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] smk_fetch.part.24+0x5a/0xf0 security/smack/smack_lsm.c:273 smk_fetch security/smack/smack_lsm.c:3548 [inline] smack_d_instantiate+0x94e/0xea0 security/smack/smack_lsm.c:3502 security_d_instantiate+0x5c/0xf0 security/security.c:1287 d_instantiate+0x5e/0xa0 fs/dcache.c:1870 shmem_mknod+0x189/0x1f0 mm/shmem.c:2814 vfs_mknod+0x445/0x800 fs/namei.c:3719 handle_create+0x1ff/0x730 drivers/base/devtmpfs.c:211 handle drivers/base/devtmpfs.c:374 [inline] devtmpfsd+0x27f/0x4c0 drivers/base/devtmpfs.c:400 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 -> #1 (&isp->smk_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0x166/0x1700 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 smack_d_instantiate+0x136/0xea0 security/smack/smack_lsm.c:3369 security_d_instantiate+0x5c/0xf0 security/security.c:1287 d_instantiate_new+0x70/0x160 fs/dcache.c:1889 ext4_add_nondir+0x81/0x90 fs/ext4/namei.c:2415 ext4_symlink+0x752/0x1130 fs/ext4/namei.c:3162 vfs_symlink+0x37a/0x5d0 fs/namei.c:4127 do_symlinkat+0x242/0x2d0 fs/namei.c:4154 __do_sys_symlink fs/namei.c:4173 [inline] __se_sys_symlink fs/namei.c:4171 [inline] __x64_sys_symlink+0x59/0x80 fs/namei.c:4171 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (jbd2_handle){++++}: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 start_this_handle+0x5b8/0x1250 fs/jbd2/transaction.c:385 jbd2__journal_start+0x3c9/0xa90 fs/jbd2/transaction.c:439 __ext4_journal_start_sb+0x1a5/0x5f0 fs/ext4/ext4_jbd2.c:81 __ext4_journal_start fs/ext4/ext4_jbd2.h:311 [inline] ext4_dirty_inode+0x62/0xc0 fs/ext4/inode.c:6023 __mark_inode_dirty+0x7c3/0x1510 fs/fs-writeback.c:2129 mark_inode_dirty_sync include/linux/fs.h:2073 [inline] iput+0x131/0xa90 fs/inode.c:1570 dentry_unlink_inode+0x461/0x5e0 fs/dcache.c:374 __dentry_kill+0x44c/0x7a0 fs/dcache.c:566 shrink_dentry_list+0x32f/0x800 fs/dcache.c:1079 prune_dcache_sb+0x12f/0x1c0 fs/dcache.c:1171 super_cache_scan+0x270/0x480 fs/super.c:102 do_shrink_slab+0x4e7/0xd20 mm/vmscan.c:547 shrink_slab+0x389/0x8c0 mm/vmscan.c:697 shrink_node+0x431/0x16b0 mm/vmscan.c:2746 kswapd_shrink_node mm/vmscan.c:3468 [inline] balance_pgdat+0x7ca/0x1000 mm/vmscan.c:3578 kswapd+0x857/0x12d0 mm/vmscan.c:3800 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 other info that might help us debug this: Chain exists of: jbd2_handle --> &isp->smk_lock --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&isp->smk_lock); lock(fs_reclaim); lock(jbd2_handle); *** DEADLOCK *** 3 locks held by kswapd0/1375: #0: 00000000f22b8da2 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:4539 #1: 00000000f5da7355 (shrinker_rwsem){++++}, at: shrink_slab+0x207/0x8c0 mm/vmscan.c:687 #2: 000000009d2c78fa (&type->s_umount_key#29){++++}, at: trylock_super+0x22/0x110 fs/super.c:412 stack backtrace: CPU: 0 PID: 1375 Comm: kswapd0 Not tainted 4.19.0-rc6+ #42 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 print_circular_bug.isra.33.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1861 [inline] check_prevs_add kernel/locking/lockdep.c:1974 [inline] validate_chain kernel/locking/lockdep.c:2415 [inline] __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900 start_this_handle+0x5b8/0x1250 fs/jbd2/transaction.c:385 jbd2__journal_start+0x3c9/0xa90 fs/jbd2/transaction.c:439 __ext4_journal_start_sb+0x1a5/0x5f0 fs/ext4/ext4_jbd2.c:81 __ext4_journal_start fs/ext4/ext4_jbd2.h:311 [inline] ext4_dirty_inode+0x62/0xc0 fs/ext4/inode.c:6023 __mark_inode_dirty+0x7c3/0x1510 fs/fs-writeback.c:2129 mark_inode_dirty_sync include/linux/fs.h:2073 [inline] iput+0x131/0xa90 fs/inode.c:1570 dentry_unlink_inode+0x461/0x5e0 fs/dcache.c:374 __dentry_kill+0x44c/0x7a0 fs/dcache.c:566 shrink_dentry_list+0x32f/0x800 fs/dcache.c:1079 prune_dcache_sb+0x12f/0x1c0 fs/dcache.c:1171 super_cache_scan+0x270/0x480 fs/super.c:102 do_shrink_slab+0x4e7/0xd20 mm/vmscan.c:547 shrink_slab+0x389/0x8c0 mm/vmscan.c:697 shrink_node+0x431/0x16b0 mm/vmscan.c:2746 kswapd_shrink_node mm/vmscan.c:3468 [inline] balance_pgdat+0x7ca/0x1000 mm/vmscan.c:3578 kswapd+0x857/0x12d0 mm/vmscan.c:3800 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 kobject: 'nullb0' (00000000b9f0be29): kobject_uevent_env kobject: 'nullb0' (00000000b9f0be29): fill_kobj_path: path = '/devices/virtual/block/nullb0'