linux-kernel - Re: [syzbot] [exfat?] INFO: task hung in exfat_write

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Message-ID: <000000000000826f8f060b59d4ea@google.com>
Date:   Wed, 29 Nov 2023 23:45:05 -0800
From:   syzbot <syzbot+2f73ed585f115e98aee8@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, lizhi.xu@...driver.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [exfat?] INFO: task hung in exfat_write_inode

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: bad unlock balance in __exfat_truncate

=====================================
WARNING: bad unlock balance detected!
6.1.0-syzkaller-11044-gf9ff5644bcc0-dirty #0 Not tainted
-------------------------------------
syz-executor.1/5525 is trying to release lock (&sbi->s_lock) at:
[<ffffffff8247908a>] __exfat_truncate+0x45a/0x7f0 fs/exfat/file.c:163
but there are no more locks to release!

other info that might help us debug this:
4 locks held by syz-executor.1/5525:
 #0: ffff88802a1e4460 (sb_writers#14){.+.+}-{0:0}, at: do_renameat2+0x3eb/0xd20 fs/namei.c:4866
 #1: ffff88802a1e4748 (&type->s_vfs_rename_key#2){+.+.}-{3:3}, at: lock_rename+0x58/0x280 fs/namei.c:2994
 #2: ffff88806489b970 (&sb->s_type->i_mutex_key#21/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
 #2: ffff88806489b970 (&sb->s_type->i_mutex_key#21/1){+.+.}-{3:3}, at: lock_rename+0xa4/0x280 fs/namei.c:2998
 #3: ffff88806489d9b0 (&sb->s_type->i_mutex_key#21/2){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
 #3: ffff88806489d9b0 (&sb->s_type->i_mutex_key#21/2){+.+.}-{3:3}, at: lock_rename+0xd8/0x280 fs/namei.c:2999

stack backtrace:
CPU: 1 PID: 5525 Comm: syz-executor.1 Not tainted 6.1.0-syzkaller-11044-gf9ff5644bcc0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x100/0x178 lib/dump_stack.c:106
 print_unlock_imbalance_bug include/trace/events/lock.h:69 [inline]
 __lock_release kernel/locking/lockdep.c:5345 [inline]
 lock_release.cold+0x49/0x4e kernel/locking/lockdep.c:5688
 __mutex_unlock_slowpath+0xa3/0x640 kernel/locking/mutex.c:907
 __exfat_truncate+0x45a/0x7f0 fs/exfat/file.c:163
 exfat_evict_inode+0x263/0x340 fs/exfat/inode.c:624
 evict+0x2ed/0x6b0 fs/inode.c:664
 iput_final fs/inode.c:1747 [inline]
 iput.part.0+0x5ea/0x8c0 fs/inode.c:1773
 iput+0x5c/0x80 fs/inode.c:1763
 dentry_unlink_inode+0x292/0x430 fs/dcache.c:401
 __dentry_kill+0x3b8/0x640 fs/dcache.c:607
 dentry_kill fs/dcache.c:745 [inline]
 dput+0x6aa/0xf70 fs/dcache.c:913
 do_renameat2+0x46a/0xd20 fs/namei.c:4932
 __do_sys_rename fs/namei.c:4976 [inline]
 __se_sys_rename fs/namei.c:4974 [inline]
 __x64_sys_rename+0x81/0xa0 fs/namei.c:4974
 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: 0033:0x7f464c67cb29
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:00007f464361e0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f464c79c050 RCX: 00007f464c67cb29
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000020000040
RBP: 00007f464c6c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f464c79c050 R15: 00007ffd9781fcc8
 </TASK>


Tested on:

commit:         f9ff5644 Merge tag 'hsi-for-6.2' of git://git.kernel.o..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1140c364e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1bf08f50e8fff9ad
dashboard link: https://syzkaller.appspot.com/bug?extid=2f73ed585f115e98aee8
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12aa5254e80000