Re: [syzbot] [jffs2?] WARNING: bad unlock balance in jffs2_do_create

[syzbot <syzbot+250fde257a3eebba4426@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    4dd16e31135e Merge tag 'net-7.4-rc1' of git://git.kernel.o..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=120d9b8e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4a49f7c2815c8df7
dashboard link: https://syzkaller.appspot.com/bug?extid=250fde257a3eebba4426
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10dd8129580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+250fde257a3eebba4426@syzkaller.appspotmail.com

jffs2: Write of 68 bytes at 0x0001e00c failed. returned -12, retlen 0
jffs2: Not marking the space at 0x0001e00c as dirty because the flash driver returned retlen zero
=====================================
WARNING: bad unlock balance detected!
syzkaller #0 Not tainted
-------------------------------------
syz-executor317/5670 is trying to release lock (&c->alloc_sem) at:
[<ffffffff834f8efe>] jffs2_do_create+0x1ae/0xe00 fs/jffs2/write.c:474
but there are no more locks to release!

other info that might help us debug this:
locks held by syz-executor317/5670: 2, last CPU#0:
 #0: ffff888049484460 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:531
 #1: ffff8880144cd800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff8880144cd800 (&type->i_mutex_dir_key#8){+.+.}-{4:4}, at: lookup_open+0x246/0x1970 fs/namei.c:4462

stack backtrace:
CPU: 0 UID: 0 PID: 5670 Comm: syz-executor317 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0xdc/0xf0 kernel/locking/lockdep.c:5349
 __lock_release kernel/locking/lockdep.c:5590 [inline]
 lock_release+0x252/0x3c0 kernel/locking/lockdep.c:5964
 __mutex_unlock_slowpath+0x88/0x900 kernel/locking/mutex.c:989
 jffs2_do_create+0x1ae/0xe00 fs/jffs2/write.c:474
 jffs2_create+0x1c8/0x320 fs/jffs2/dir.c:205
 lookup_open+0xedc/0x1970 fs/namei.c:4569
 open_last_lookups fs/namei.c:4768 [inline]
 path_openat+0x70c/0x20f0 fs/namei.c:5007
 do_file_open+0x23e/0x4a0 fs/namei.c:5039
 do_sys_openat2+0x115/0x200 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_creat fs/open.c:1526 [inline]
 __se_sys_creat fs/open.c:1520 [inline]
 __x64_sys_creat+0x8f/0xc0 fs/open.c:1520
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3e047ea0f7
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff7c755290 EFLAGS: 00000202 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000555569e9a400 RCX: 00007f3e047ea0f7
RDX: 0000000000000000 RSI: 00000000000001a4 RDI: 00007f3e04827201
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f3e04827235
R13: 00007f3e04827252 R14: 000000000000000e R15: 0000000000020000
 </TASK>


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