Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
MIME-Version: 1.0
Date:   Wed, 20 Sep 2023 02:13:53 -0700
In-Reply-To: <0000000000001825ce06047bf2a6@google.com>
Message-ID: <0000000000005e0f2b0605c6cb3e@google.com>
Subject: Re: [syzbot] [reiserfs?] possible deadlock in super_lock
From:   syzbot <syzbot+062317ea1d0a6d5e29e7@syzkaller.appspotmail.com>
To:     chao@kernel.org, jaegeuk@kernel.org,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        reiserfs-devel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        terrelln@fb.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

syzbot has found a reproducer for the following issue on:

HEAD commit:    2cf0f7156238 Merge tag 'nfs-for-6.6-2' of git://git.linux-..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12780282680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=710dc49bece494df
dashboard link: https://syzkaller.appspot.com/bug?extid=062317ea1d0a6d5e29e7
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107e9518680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f48f4ed701b8/disk-2cf0f715.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b8491e29a2d/vmlinux-2cf0f715.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90faa04d6558/bzImage-2cf0f715.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c98194587df7/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+062317ea1d0a6d5e29e7@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0 Not tainted
------------------------------------------------------
syz-executor.0/8792 is trying to acquire lock:
ffff88807993a0e0 (&type->s_umount_key#25){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
ffff88807993a0e0 (&type->s_umount_key#25){++++}-{3:3}, at: super_lock+0x23c/0x380 fs/super.c:117

but task is already holding lock:
ffff888148439388 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:370 [inline]
ffff888148439388 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x14e9/0x1ce0 block/ioctl.c:502

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&bdev->bd_holder_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       bdev_mark_dead+0x25/0x230 block/bdev.c:961
       disk_force_media_change+0x51/0x80 block/disk-events.c:303
       __loop_clr_fd+0x3ab/0x8f0 drivers/block/loop.c:1174
       lo_release+0x188/0x1c0 drivers/block/loop.c:1743
       blkdev_put_whole+0xa5/0xe0 block/bdev.c:663
       blkdev_put+0x40f/0x8e0 block/bdev.c:898
       kill_block_super+0x58/0x70 fs/super.c:1649
       deactivate_locked_super+0x9a/0x170 fs/super.c:481
       deactivate_super+0xde/0x100 fs/super.c:514
       cleanup_mnt+0x222/0x3d0 fs/namespace.c:1254
       task_work_run+0x14d/0x240 kernel/task_work.c:179
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
       exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
       do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&disk->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       blkdev_get_by_dev.part.0+0x4f0/0xb20 block/bdev.c:786
       blkdev_get_by_dev+0x75/0x80 block/bdev.c:829
       journal_init_dev fs/reiserfs/journal.c:2626 [inline]
       journal_init+0xbb8/0x64b0 fs/reiserfs/journal.c:2786
       reiserfs_fill_super+0xcc6/0x3150 fs/reiserfs/super.c:2022
       mount_bdev+0x1f3/0x2e0 fs/super.c:1629
       legacy_get_tree+0x109/0x220 fs/fs_context.c:638
       vfs_get_tree+0x8c/0x370 fs/super.c:1750
       do_new_mount fs/namespace.c:3335 [inline]
       path_mount+0x1492/0x1ed0 fs/namespace.c:3662
       do_mount fs/namespace.c:3675 [inline]
       __do_sys_mount fs/namespace.c:3884 [inline]
       __se_sys_mount fs/namespace.c:3861 [inline]
       __x64_sys_mount+0x293/0x310 fs/namespace.c:3861
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&type->s_umount_key#25){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
       down_read+0x9c/0x470 kernel/locking/rwsem.c:1520
       __super_lock fs/super.c:58 [inline]
       super_lock+0x23c/0x380 fs/super.c:117
       super_lock_shared fs/super.c:146 [inline]
       super_lock_shared_active fs/super.c:1431 [inline]
       fs_bdev_sync+0x94/0x1b0 fs/super.c:1466
       blkdev_flushbuf block/ioctl.c:372 [inline]
       blkdev_common_ioctl+0x1550/0x1ce0 block/ioctl.c:502
       blkdev_ioctl+0x249/0x770 block/ioctl.c:624
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  &type->s_umount_key#25 --> &disk->open_mutex --> &bdev->bd_holder_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&bdev->bd_holder_lock);
                               lock(&disk->open_mutex);
                               lock(&bdev->bd_holder_lock);
  rlock(&type->s_umount_key#25);

 *** DEADLOCK ***

1 lock held by syz-executor.0/8792:
 #0: ffff888148439388 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:370 [inline]
 #0: ffff888148439388 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x14e9/0x1ce0 block/ioctl.c:502

stack backtrace:
CPU: 0 PID: 8792 Comm: syz-executor.0 Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x311/0x3f0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3868 [inline]
 __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
 down_read+0x9c/0x470 kernel/locking/rwsem.c:1520
 __super_lock fs/super.c:58 [inline]
 super_lock+0x23c/0x380 fs/super.c:117
 super_lock_shared fs/super.c:146 [inline]
 super_lock_shared_active fs/super.c:1431 [inline]
 fs_bdev_sync+0x94/0x1b0 fs/super.c:1466
 blkdev_flushbuf block/ioctl.c:372 [inline]
 blkdev_common_ioctl+0x1550/0x1ce0 block/ioctl.c:502
 blkdev_ioctl+0x249/0x770 block/ioctl.c:624
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f18ae67cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f18af4830c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f18ae79bf80 RCX: 00007f18ae67cae9
RDX: 0000000000000003 RSI: 0000000000001261 RDI: 0000000000000003
RBP: 00007f18ae6c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f18ae79bf80 R15: 00007ffc4185a478
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.