syzbot

REISERFS (device loop0): journal params: device loop0, size 512, journal first block 18, max trans len 256, max batch 225, max commit age 30, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using rupasov hash to sort names
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
4.19.211-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor354/8116 is trying to acquire lock:
000000007f2605d2 (&type->i_mutex_dir_key#7){+.+.}, at: inode_lock include/linux/fs.h:748 [inline]
000000007f2605d2 (&type->i_mutex_dir_key#7){+.+.}, at: do_last fs/namei.c:3324 [inline]
000000007f2605d2 (&type->i_mutex_dir_key#7){+.+.}, at: path_openat+0x1071/0x2df0 fs/namei.c:3537

but task is already holding lock:
0000000026aeeee5 (sb_writers#11){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline]
0000000026aeeee5 (sb_writers#11){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#11){.+.+}:
       sb_start_write include/linux/fs.h:1579 [inline]
       mnt_want_write_file+0x63/0x1d0 fs/namespace.c:418
       reiserfs_ioctl+0x1a7/0x9a0 fs/reiserfs/ioctl.c:110
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:501 [inline]
       do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
       ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
       __do_sys_ioctl fs/ioctl.c:712 [inline]
       __se_sys_ioctl fs/ioctl.c:710 [inline]
       __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&sbi->lock){+.+.}:
       reiserfs_write_lock+0x75/0xf0 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x171/0x490 fs/reiserfs/namei.c:363
       __lookup_slow+0x246/0x4a0 fs/namei.c:1672
       lookup_one_len+0x163/0x190 fs/namei.c:2544
       reiserfs_lookup_privroot+0x92/0x280 fs/reiserfs/xattr.c:970
       reiserfs_fill_super+0x1f12/0x2d80 fs/reiserfs/super.c:2187
       mount_bdev+0x2fc/0x3b0 fs/super.c:1158
       mount_fs+0xa3/0x310 fs/super.c:1261
       vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
       vfs_kern_mount fs/namespace.c:951 [inline]
       do_new_mount fs/namespace.c:2492 [inline]
       do_mount+0x115c/0x2f50 fs/namespace.c:2822
       ksys_mount+0xcf/0x130 fs/namespace.c:3038
       __do_sys_mount fs/namespace.c:3052 [inline]
       __se_sys_mount fs/namespace.c:3049 [inline]
       __x64_sys_mount+0xba/0x150 fs/namespace.c:3049
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&type->i_mutex_dir_key#7){+.+.}:
       down_write+0x34/0x90 kernel/locking/rwsem.c:70
       inode_lock include/linux/fs.h:748 [inline]
       do_last fs/namei.c:3324 [inline]
       path_openat+0x1071/0x2df0 fs/namei.c:3537
       do_filp_open+0x18c/0x3f0 fs/namei.c:3567
       do_sys_open+0x3b3/0x520 fs/open.c:1085
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#7 --> &sbi->lock --> sb_writers#11

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#11);
                               lock(&sbi->lock);
                               lock(sb_writers#11);
  lock(&type->i_mutex_dir_key#7);

 *** DEADLOCK ***

1 lock held by syz-executor354/8116:
 #0: 0000000026aeeee5 (sb_writers#11){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline]
 #0: 0000000026aeeee5 (sb_writers#11){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360

stack backtrace:
CPU: 1 PID: 8116 Comm: syz-executor354 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222
 check_prev_add kernel/locking/lockdep.c:1866 [inline]
 check_prevs_add kernel/locking/lockdep.c:1979 [inline]
 validate_chain kernel/locking/lockdep.c:2420 [inline]
 __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
 down_write+0x34/0x90 kernel/locking/rwsem.c:70
 inode_lock include/linux/fs.h:748 [inline]
 do_last fs/namei.c:3324 [inline]
 path_openat+0x1071/0x2df0 fs/namei.c:3537
 do_filp_open+0x18c/0x3f0 fs/namei.c:3567
 do_sys_open+0x3b3/0x520 fs/open.c:1085
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fbd0927a8a9
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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc36923f38 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbd0927a8a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000040
RBP: 0000000000000000 R08: 00007fbd092e8ec0 R09: 00007fbd092e8ec0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc36923f60
R13: 0000000000000000 R14: 431bde82d7b634db R15: 0000000000000000