[syzbot] [reiserfs?] possible deadlock in do_unlinkat

From: syzbot
Date: Mon May 29 2023 - 13:13:57 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 933174ae28ba Merge tag 'spi-fix-v6.4-rc3' of git://git.ker..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=167d464d280000
kernel config: https://syzkaller.appspot.com/x/.config?x=7d8067683055e3f5
dashboard link: https://syzkaller.appspot.com/bug?extid=ada12d2d935bbc82aa7f
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=106e6d19280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13cf84e5280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/189d556c105e/disk-933174ae.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/498458304963/vmlinux-933174ae.xz
kernel image: https://storage.googleapis.com/syzbot-assets/68bcd9d7c04c/bzImage-933174ae.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/a89e85025777/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ada12d2d935bbc82aa7f@xxxxxxxxxxxxxxxxxxxxxxxxx

REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc3-syzkaller-00032-g933174ae28ba #0 Not tainted
------------------------------------------------------
syz-executor392/4995 is trying to acquire lock:
ffff888022309090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7a/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff8880759902e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline]
ffff8880759902e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x26a/0x950 fs/namei.c:4378

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:
lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:810 [inline]
do_unlinkat+0x26a/0x950 fs/namei.c:4378
__do_sys_unlinkat fs/namei.c:4436 [inline]
__se_sys_unlinkat fs/namei.c:4429 [inline]
__x64_sys_unlinkat+0xce/0xf0 fs/namei.c:4429
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (sb_writers#9){.+.+}-{0:0}:
lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1494 [inline]
sb_start_write+0x4d/0x1c0 include/linux/fs.h:1569
mnt_want_write_file+0x5e/0x1f0 fs/namespace.c:438
reiserfs_ioctl+0x174/0x340 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 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:3108 [inline]
check_prevs_add kernel/locking/lockdep.c:3227 [inline]
validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3842
__lock_acquire+0x1295/0x2000 kernel/locking/lockdep.c:5074
lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
__mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7a/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x162/0x580 fs/reiserfs/namei.c:364
lookup_one_qstr_excl+0x11b/0x250 fs/namei.c:1605
do_unlinkat+0x298/0x950 fs/namei.c:4379
__do_sys_unlinkat fs/namei.c:4436 [inline]
__se_sys_unlinkat fs/namei.c:4429 [inline]
__x64_sys_unlinkat+0xce/0xf0 fs/namei.c:4429
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&sbi->lock --> sb_writers#9 --> &type->i_mutex_dir_key#6/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#6/1);
lock(sb_writers#9);
lock(&type->i_mutex_dir_key#6/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor392/4995:
#0: ffff88807d18c460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394
#1: ffff8880759902e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline]
#1: ffff8880759902e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x26a/0x950 fs/namei.c:4378

stack backtrace:
CPU: 0 PID: 4995 Comm: syz-executor392 Not tainted 6.4.0-rc3-syzkaller-00032-g933174ae28ba #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/16/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
check_noncircular+0x2fe/0x3b0 kernel/locking/lockdep.c:2188
check_prev_add kernel/locking/lockdep.c:3108 [inline]
check_prevs_add kernel/locking/lockdep.c:3227 [inline]
validate_chain+0x166b/0x58e0 kernel/locking/lockdep.c:3842
__lock_acquire+0x1295/0x2000 kernel/locking/lockdep.c:5074
lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
__mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7a/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x162/0x580 fs/reiserfs/namei.c:364
lookup_one_qstr_excl+0x11b/0x250 fs/namei.c:1605
do_unlinkat+0x298/0x950 fs/namei.c:4379
__do_sys_unlinkat fs/namei.c:4436 [inline]
__se_sys_unlinkat fs/namei.c:4429 [inline]
__x64_sys_unlinkat+0xce/0xf0 fs/namei.c:4429
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ffa0fa838f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 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 c0 ff ff ff f7 d8 64 89 01 48

---
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Next message: Sui Jingfeng: "[PATCH v4 2/6] drm/etnaviv: add a dedicated function to get various clocks"
Previous message: Vlastimil Babka: "Re: [PATCH 5/5] mm: compaction: drop redundant watermark check in compaction_zonelist_suitable()"
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