====================================================== WARNING: possible circular locking dependency detected 4.14.211-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.5/13849 is trying to acquire lock: (&oi->lock){+.+.}, at: [] ovl_nlink_start+0x22f/0x460 fs/overlayfs/util.c:523 but task is already holding lock: (sb_writers#3){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] (sb_writers#3){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x64/0x260 fs/super.c:1342 sb_start_write include/linux/fs.h:1549 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 ovl_do_remove+0x67/0xb90 fs/overlayfs/dir.c:759 vfs_rmdir.part.0+0x144/0x390 fs/namei.c:3908 vfs_rmdir fs/namei.c:3893 [inline] do_rmdir+0x334/0x3c0 fs/namei.c:3968 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: down_read+0x36/0x80 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:729 [inline] lookup_slow+0x129/0x400 fs/namei.c:1674 lookup_one_len_unlocked+0x3a0/0x410 fs/namei.c:2595 ovl_lower_positive+0x184/0x345 fs/overlayfs/namei.c:783 ovl_rename+0x47c/0xf10 fs/overlayfs/dir.c:968 vfs_rename+0x560/0x1820 fs/namei.c:4496 SYSC_renameat2 fs/namei.c:4644 [inline] SyS_renameat2+0x95b/0xad0 fs/namei.c:4533 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb -> #0 (&oi->lock){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 ovl_nlink_start+0x22f/0x460 fs/overlayfs/util.c:523 ovl_do_remove+0xd4/0xb90 fs/overlayfs/dir.c:767 vfs_unlink+0x230/0x470 fs/namei.c:4027 do_unlinkat+0x30c/0x5c0 fs/namei.c:4092 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb other info that might help us debug this: Chain exists of: &oi->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#3); lock(&ovl_i_mutex_dir_key[depth]); lock(sb_writers#3); lock(&oi->lock); *** DEADLOCK *** 4 locks held by syz-executor.5/13849: #0: (sb_writers#16){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] #0: (sb_writers#16){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 #1: (&ovl_i_mutex_dir_key[depth]/1){+.+.}, at: [] inode_lock_nested include/linux/fs.h:754 [inline] #1: (&ovl_i_mutex_dir_key[depth]/1){+.+.}, at: [] do_unlinkat+0x201/0x5c0 fs/namei.c:4078 #2: (&ovl_i_mutex_key[depth]#2){+.+.}, at: [] inode_lock include/linux/fs.h:719 [inline] #2: (&ovl_i_mutex_key[depth]#2){+.+.}, at: [] vfs_unlink+0xc0/0x470 fs/namei.c:4018 #3: (sb_writers#3){.+.+}, at: [] sb_start_write include/linux/fs.h:1549 [inline] #3: (sb_writers#3){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 stack backtrace: CPU: 0 PID: 13849 Comm: syz-executor.5 Not tainted 4.14.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x283 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 ovl_nlink_start+0x22f/0x460 fs/overlayfs/util.c:523 ovl_do_remove+0xd4/0xb90 fs/overlayfs/dir.c:767 vfs_unlink+0x230/0x470 fs/namei.c:4027 do_unlinkat+0x30c/0x5c0 fs/namei.c:4092 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45e0f9 RSP: 002b:00007f9ccbba7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000045e0f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080 RBP: 000000000119bfb0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c R13: 00007ffe4945217f R14: 00007f9ccbba89c0 R15: 000000000119bf8c overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection. Cannot find set identified by id 0 to match Cannot find set identified by id 0 to match Cannot find set identified by id 0 to match Cannot find set identified by id 0 to match FAT-fs (loop1): bread failed, FSINFO block (sector = 1) blktrace: Concurrent blktraces are not allowed on sg0 FAT-fs (loop1): bread failed, FSINFO block (sector = 1) blktrace: Concurrent blktraces are not allowed on sg0 FAT-fs (loop1): bread failed, FSINFO block (sector = 1) blktrace: Concurrent blktraces are not allowed on sg0 FAT-fs (loop1): bread failed, FSINFO block (sector = 1) PM: Marking nosave pages: [mem 0x00000000-0x00000fff] PM: Marking nosave pages: [mem 0x0009f000-0x000fffff] PM: Marking nosave pages: [mem 0xbfffd000-0xffffffff] PM: Basic memory bitmaps created PM: Basic memory bitmaps freed PM: Marking nosave pages: [mem 0x00000000-0x00000fff] PM: Marking nosave pages: [mem 0x0009f000-0x000fffff] PM: Marking nosave pages: [mem 0xbfffd000-0xffffffff] PM: Basic memory bitmaps created PM: Basic memory bitmaps freed