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Message-ID: <000000000000d6ae9205f091d8d7@google.com>
Date:   Sat, 24 Dec 2022 04:14:42 -0800
From:   syzbot <syzbot+435320768a3c52aa94b6@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, reiserfs-devel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: [syzbot] [reiserfs?] possible deadlock in iterate_dir

Hello,

syzbot found the following issue on:

HEAD commit:    6feb57c2fd7c Merge tag 'kbuild-v6.2' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1012ba27880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8ca07260bb631fb4
dashboard link: https://syzkaller.appspot.com/bug?extid=435320768a3c52aa94b6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9ebad0b8683b/disk-6feb57c2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/18fd8f90d2d6/vmlinux-6feb57c2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/841ab00c6df1/bzImage-6feb57c2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+435320768a3c52aa94b6@...kaller.appspotmail.com

REISERFS (device loop4): Using r5 hash to sort names
REISERFS (device loop4): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-syzkaller-13822-g6feb57c2fd7c #0 Not tainted
------------------------------------------------------
syz-executor.4/9537 is trying to acquire lock:
ffff8880767ab090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88801d266460 (sb_writers#19){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2516 [inline]
ffff88801d266460 (sb_writers#19){.+.+}-{0:0}, at: iterate_dir+0x45d/0x6f0 fs/readdir.c:70

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sb_writers#19){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1811 [inline]
       sb_start_write include/linux/fs.h:1886 [inline]
       mnt_want_write_file+0x92/0x590 fs/namespace.c:552
       reiserfs_ioctl+0x1a2/0x330 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sbi->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
       lock_acquire kernel/locking/lockdep.c:5668 [inline]
       lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
       reiserfs_dirty_inode+0xd2/0x260 fs/reiserfs/super.c:704
       __mark_inode_dirty+0x247/0x11e0 fs/fs-writeback.c:2419
       generic_update_time fs/inode.c:1859 [inline]
       inode_update_time fs/inode.c:1872 [inline]
       touch_atime+0x641/0x700 fs/inode.c:1944
       file_accessed include/linux/fs.h:2516 [inline]
       iterate_dir+0x45d/0x6f0 fs/readdir.c:70
       __do_sys_getdents fs/readdir.c:286 [inline]
       __se_sys_getdents fs/readdir.c:271 [inline]
       __x64_sys_getdents+0x13e/0x2c0 fs/readdir.c:271
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#19);
                               lock(&sbi->lock);
                               lock(sb_writers#19);
  lock(&sbi->lock);

 *** DEADLOCK ***

3 locks held by syz-executor.4/9537:
 #0: ffff88801d6b6fe8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe7/0x100 fs/file.c:1046
 #1: ffff888031b80980 (&type->i_mutex_dir_key#13){++++}-{3:3}, at: iterate_dir+0xd1/0x6f0 fs/readdir.c:55
 #2: ffff88801d266460 (sb_writers#19){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2516 [inline]
 #2: ffff88801d266460 (sb_writers#19){.+.+}-{0:0}, at: iterate_dir+0x45d/0x6f0 fs/readdir.c:70

stack backtrace:
CPU: 0 PID: 9537 Comm: syz-executor.4 Not tainted 6.1.0-syzkaller-13822-g6feb57c2fd7c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
 reiserfs_dirty_inode+0xd2/0x260 fs/reiserfs/super.c:704
 __mark_inode_dirty+0x247/0x11e0 fs/fs-writeback.c:2419
 generic_update_time fs/inode.c:1859 [inline]
 inode_update_time fs/inode.c:1872 [inline]
 touch_atime+0x641/0x700 fs/inode.c:1944
 file_accessed include/linux/fs.h:2516 [inline]
 iterate_dir+0x45d/0x6f0 fs/readdir.c:70
 __do_sys_getdents fs/readdir.c:286 [inline]
 __se_sys_getdents fs/readdir.c:271 [inline]
 __x64_sys_getdents+0x13e/0x2c0 fs/readdir.c:271
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f93e5e8c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f93e6baa168 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f93e5fabf80 RCX: 00007f93e5e8c0d9
RDX: 0000000000000072 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f93e5ee7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff02abfe4f R14: 00007f93e6baa300 R15: 0000000000022000
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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