====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.3953/17757 is trying to acquire lock: ffff888054b43b38 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:884 [inline] ffff888054b43b38 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_slow fs/namei.c:1824 [inline] ffff888054b43b38 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: walk_component+0x345/0x5b0 fs/namei.c:2129 but task is already holding lock: ffff8880420a4088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 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:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 kernfs_seq_start+0x4d/0x240 fs/kernfs/file.c:154 seq_read_iter+0x2be/0x12c0 fs/seq_file.c:225 kernfs_fop_read_iter+0x40f/0x5a0 fs/kernfs/file.c:279 do_iter_readv_writev+0x740/0x9e0 fs/read_write.c:825 vfs_readv+0x4cb/0x8b0 fs/read_write.c:1018 do_readv+0x132/0x340 fs/read_write.c:1080 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&p->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 seq_read_iter+0xe1/0x12c0 fs/seq_file.c:182 kernfs_fop_read_iter+0x40f/0x5a0 fs/kernfs/file.c:279 copy_splice_read+0x615/0xc20 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+0x109/0x120 fs/splice.c:1292 do_sendfile+0x400/0xe50 fs/read_write.c:1376 __do_sys_sendfile64 fs/read_write.c:1431 [inline] __se_sys_sendfile64 fs/read_write.c:1417 [inline] __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 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:598 [inline] __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 pipe_lock fs/pipe.c:91 [inline] pipe_lock+0x64/0x80 fs/pipe.c:88 iter_file_splice_write+0x1ea/0x12e0 fs/splice.c:683 do_splice_from fs/splice.c:938 [inline] do_splice+0x1478/0x1fc0 fs/splice.c:1351 __do_splice+0x32a/0x360 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+0xcd/0x4c0 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.h:1798 [inline] sb_start_write include/linux/fs.h:1934 [inline] mnt_want_write+0x6f/0x450 fs/namespace.c:557 ovl_create_object+0x12c/0x300 fs/overlayfs/dir.c:651 lookup_open.isra.0+0x11d0/0x1580 fs/namei.c:3708 open_last_lookups fs/namei.c:3807 [inline] path_openat+0x893/0x2cb0 fs/namei.c:4043 do_filp_open+0x20b/0x470 fs/namei.c:4073 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 do_sys_open fs/open.c:1450 [inline] __do_sys_openat fs/open.c:1466 [inline] __se_sys_openat fs/open.c:1461 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1461 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:884 [inline] lookup_slow fs/namei.c:1824 [inline] walk_component+0x345/0x5b0 fs/namei.c:2129 lookup_last fs/namei.c:2630 [inline] path_lookupat+0x142/0x6d0 fs/namei.c:2654 filename_lookup+0x224/0x5f0 fs/namei.c:2683 kern_path+0x35/0x50 fs/namei.c:2816 lookup_bdev+0xd8/0x280 block/bdev.c:1205 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1295 kobj_attr_store+0x55/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7d0/0x11d0 fs/read_write.c:686 ksys_write+0x12a/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 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.1.3953/17757: #0: ffff88803aa05438 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1232 #1: ffff88802d46c428 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:738 #2: ffff8880420a4088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 #3: ffff88801c39ab48 (kn->active#82){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2b2/0x510 fs/kernfs/file.c:326 stack backtrace: CPU: 3 UID: 0 PID: 17757 Comm: syz.1.3953 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 lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043 check_noncircular+0x14c/0x170 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:884 [inline] lookup_slow fs/namei.c:1824 [inline] walk_component+0x345/0x5b0 fs/namei.c:2129 lookup_last fs/namei.c:2630 [inline] path_lookupat+0x142/0x6d0 fs/namei.c:2654 filename_lookup+0x224/0x5f0 fs/namei.c:2683 kern_path+0x35/0x50 fs/namei.c:2816 lookup_bdev+0xd8/0x280 block/bdev.c:1205 resume_store+0x1d6/0x460 kernel/power/hibernate.c:1295 kobj_attr_store+0x55/0x80 lib/kobject.c:840 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x354/0x510 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7d0/0x11d0 fs/read_write.c:686 ksys_write+0x12a/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f89b938ebe9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f89ba133038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f89b95b5fa0 RCX: 00007f89b938ebe9 RDX: 0000000000000012 RSI: 0000200000000040 RDI: 0000000000000003 RBP: 00007f89b9411e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f89b95b6038 R14: 00007f89b95b5fa0 R15: 00007ffc2e9f0308 PM: Image not found (code -5)