====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.6.3261/16705 is trying to acquire lock: ffff888057840cd8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1043 [inline] ffff888057840cd8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_slow+0x42/0x70 fs/namei.c:1932 but task is already holding lock: ffff88805620b088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&of->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:172 traverse.part.0.constprop.0+0xaf/0x650 fs/seq_file.c:107 traverse fs/seq_file.c:99 [inline] seq_read_iter+0x93f/0x1270 fs/seq_file.c:196 kernfs_fop_read_iter+0x46c/0x610 fs/kernfs/file.c:297 lo_rw_aio.isra.0+0x7a4/0xd60 drivers/block/loop.c:405 do_req_filebacked drivers/block/loop.c:436 [inline] loop_handle_cmd drivers/block/loop.c:1926 [inline] loop_process_work+0x86c/0x11c0 drivers/block/loop.c:1961 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275 process_scheduled_works kernel/workqueue.c:3358 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3439 kthread+0x370/0x450 kernel/kthread.c:467 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #3 (&p->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 proc_reg_read_iter+0x220/0x310 fs/proc/inode.c:299 copy_splice_read+0x4ba/0xb90 fs/splice.c:363 do_splice_read fs/splice.c:982 [inline] do_splice_read+0x285/0x370 fs/splice.c:956 splice_file_to_pipe+0x82/0x120 fs/splice.c:1292 do_sendfile+0x366/0xe20 fs/read_write.c:1378 __do_sys_sendfile64 fs/read_write.c:1433 [inline] __se_sys_sendfile64 fs/read_write.c:1419 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&pipe->mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 pipe_lock fs/pipe.c:91 [inline] pipe_lock+0x69/0x80 fs/pipe.c:88 iter_file_splice_write+0x1f8/0x10a0 fs/splice.c:683 do_splice_from fs/splice.c:938 [inline] do_splice+0x109c/0x1fd0 fs/splice.c:1351 __do_splice+0x237/0x370 fs/splice.c:1433 __do_sys_splice fs/splice.c:1636 [inline] __se_sys_splice fs/splice.c:1618 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1618 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (sb_writers#6){.+.+}-{0:0}: 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_write include/linux/fs/super.h:125 [inline] mnt_want_write+0x6f/0x450 fs/namespace.c:493 ovl_xattr_set+0x137/0x5a0 fs/overlayfs/xattrs.c:61 ovl_own_xattr_set+0x86/0xd0 fs/overlayfs/xattrs.c:204 __vfs_setxattr+0x175/0x1e0 fs/xattr.c:200 __vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:234 __vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:295 vfs_setxattr+0x14a/0x390 fs/xattr.c:321 do_setxattr+0x145/0x180 fs/xattr.c:636 filename_setxattr+0x167/0x1d0 fs/xattr.c:664 path_setxattrat+0x1ff/0x3b0 fs/xattr.c:708 __do_sys_setxattr fs/xattr.c:742 [inline] __se_sys_setxattr fs/xattr.c:738 [inline] __x64_sys_setxattr+0xc6/0x140 fs/xattr.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}: 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825 down_read+0x99/0x460 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:1043 [inline] lookup_slow+0x42/0x70 fs/namei.c:1932 walk_component fs/namei.c:2279 [inline] lookup_last fs/namei.c:2780 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2804 filename_lookup+0x202/0x590 fs/namei.c:2833 kern_path+0x37/0x50 fs/namei.c:3040 lookup_bdev+0xd8/0x280 block/bdev.c:1221 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1306 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth] --> &p->lock --> &of->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&of->mutex); lock(&p->lock); lock(&of->mutex); rlock(&ovl_i_mutex_dir_key[depth]); *** DEADLOCK *** 4 locks held by syz.6.3261/16705: #0: ffff888027a0a638 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1255 #1: ffff88802c09a420 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:740 #2: ffff88805620b088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 #3: ffff88801c360f08 (kn->active#73){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #3: ffff88801c360f08 (kn->active#73){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:344 stack backtrace: CPU: 2 UID: 0 PID: 16705 Comm: syz.6.3261 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825 down_read+0x99/0x460 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:1043 [inline] lookup_slow+0x42/0x70 fs/namei.c:1932 walk_component fs/namei.c:2279 [inline] lookup_last fs/namei.c:2780 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2804 filename_lookup+0x202/0x590 fs/namei.c:2833 kern_path+0x37/0x50 fs/namei.c:3040 lookup_bdev+0xd8/0x280 block/bdev.c:1221 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1306 kobj_attr_store+0x58/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f274a19bf79 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f274b11d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f274a415fa0 RCX: 00007f274a19bf79 RDX: 0000000000000012 RSI: 0000200000000040 RDI: 0000000000000003 RBP: 00007f274a2327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f274a416038 R14: 00007f274a415fa0 R15: 00007ffc08a030c8 block device autoloading is deprecated and will be removed. PM: Image not found (code -22)