[v6.1] possible deadlock in iterate_dir (2)

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Mar 30, 2024, 9:55:28 AMMar 30
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Hello,

syzbot found the following issue on:

HEAD commit: e5cd595e23c1 Linux 6.1.83
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1599f2b5180000
kernel config: https://syzkaller.appspot.com/x/.config?x=99d0cbbc2b2c7cfd
dashboard link: https://syzkaller.appspot.com/bug?extid=e1f54d3599ee4841393a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cd28292a2eef/disk-e5cd595e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e8297fd856b2/vmlinux-e5cd595e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea8c74634429/bzImage-e5cd595e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e1f54d...@syzkaller.appspotmail.com

REISERFS (device loop3): using 3.5.x disk format
REISERFS (device loop3): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.83-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/10456 is trying to acquire lock:
ffff88805c23e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88805690e460 (sb_writers#26){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2595 [inline]
ffff88805690e460 (sb_writers#26){.+.+}-{0:0}, at: iterate_dir+0x484/0x560 fs/readdir.c:70

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sb_writers#26){.+.+}-{0:0}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1891 [inline]
sb_start_write+0x4d/0x1c0 include/linux/fs.h:1966
mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
reiserfs_ioctl+0x170/0x340 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:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sbi->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27
reiserfs_dirty_inode+0xee/0x240 fs/reiserfs/super.c:704
__mark_inode_dirty+0x331/0xf80 fs/fs-writeback.c:2433
generic_update_time fs/inode.c:1903 [inline]
inode_update_time fs/inode.c:1916 [inline]
touch_atime+0x3fa/0x680 fs/inode.c:1988
file_accessed include/linux/fs.h:2595 [inline]
iterate_dir+0x484/0x560 fs/readdir.c:70
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64+0x209/0x4f0 fs/readdir.c:354
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_writers#26);
lock(&sbi->lock);
lock(sb_writers#26);
lock(&sbi->lock);

*** DEADLOCK ***

3 locks held by syz-executor.3/10456:
#0: ffff8880738954e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ba/0x360 fs/file.c:1062
#1: ffff888052d71d60 (&type->i_mutex_dir_key#19){++++}-{3:3}, at: iterate_dir+0x10a/0x560 fs/readdir.c:55
#2: ffff88805690e460 (sb_writers#26){.+.+}-{0:0}
, at: file_accessed include/linux/fs.h:2595 [inline]
, at: iterate_dir+0x484/0x560 fs/readdir.c:70

stack backtrace:
CPU: 0 PID: 10456 Comm: syz-executor.3 Not tainted 6.1.83-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
reiserfs_write_lock+0x76/0xd0 fs/reiserfs/lock.c:27
reiserfs_dirty_inode+0xee/0x240 fs/reiserfs/super.c:704
__mark_inode_dirty+0x331/0xf80 fs/fs-writeback.c:2433
generic_update_time fs/inode.c:1903 [inline]
inode_update_time fs/inode.c:1916 [inline]
touch_atime+0x3fa/0x680 fs/inode.c:1988
file_accessed include/linux/fs.h:2595 [inline]
iterate_dir+0x484/0x560 fs/readdir.c:70
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64+0x209/0x4f0 fs/readdir.c:354
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fb538e7dda9
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:00007fb539c9b0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fb538fabf80 RCX: 00007fb538e7dda9
RDX: 0000000000000025 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fb538eca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fb538fabf80 R15: 00007ffd736281f8
</TASK>


---
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