Date: Thu, 27 Jun 2024 16:13:49 -0700
From: syzbot <syzbot+df3558df41609451e4ac@...kaller.appspotmail.com>
To: linkinjeon@...nel.org
Cc: linkinjeon@...nel.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, sj1557.seo@...sung.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [exfat?] possible deadlock in exfat_iterate (2)

> #syz test git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat.git dev

This crash does not have a reproducer. I cannot test it.

>
> 2024년 6월 27일 (목) 오후 9:58, syzbot
> <syzbot+df3558df41609451e4ac@...kaller.appspotmail.com>님이 작성:
>>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    55027e689933 Merge tag 'input-for-v6.10-rc5' of git://git...
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=16390ac1980000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=53ab35b556129242
>> dashboard link: https://syzkaller.appspot.com/bug?extid=df3558df41609451e4ac
>> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>> userspace arch: i386
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> Downloadable assets:
>> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-55027e68.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/a36929b5a065/vmlinux-55027e68.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/d72de6f61ddc/bzImage-55027e68.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+df3558df41609451e4ac@...kaller.appspotmail.com
>>
>> ======================================================
>> WARNING: possible circular locking dependency detected
>> 6.10.0-rc5-syzkaller-00018-g55027e689933 #0 Not tainted
>> ------------------------------------------------------
>> syz-executor.2/6265 is trying to acquire lock:
>> ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:334 [inline]
>> ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3891 [inline]
>> ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3981 [inline]
>> ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:4121 [inline]
>> ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0xb5/0x420 mm/slub.c:4135
>>
>> but task is already holding lock:
>> ffff88804af1a0e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_iterate+0x33f/0xad0 fs/exfat/dir.c:256
>>
>> which lock already depends on the new lock.
>>
>>
>> the existing dependency chain (in reverse order) is:
>>
>> -> #1 (&sbi->s_lock#2){+.+.}-{3:3}:
>>        __mutex_lock_common kernel/locking/mutex.c:608 [inline]
>>        __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
>>        exfat_evict_inode+0x25b/0x340 fs/exfat/inode.c:725
>>        evict+0x2ed/0x6c0 fs/inode.c:667
>>        iput_final fs/inode.c:1741 [inline]
>>        iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
>>        iput+0x5c/0x80 fs/inode.c:1757
>>        dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
>>        __dentry_kill+0x1d0/0x600 fs/dcache.c:603
>>        shrink_kill fs/dcache.c:1048 [inline]
>>        shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
>>        prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
>>        super_cache_scan+0x32a/0x550 fs/super.c:221
>>        do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
>>        shrink_slab_memcg mm/shrinker.c:548 [inline]
>>        shrink_slab+0xa87/0x1310 mm/shrinker.c:626
>>        shrink_one+0x493/0x7c0 mm/vmscan.c:4790
>>        shrink_many mm/vmscan.c:4851 [inline]
>>        lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951
>>        shrink_node mm/vmscan.c:5910 [inline]
>>        kswapd_shrink_node mm/vmscan.c:6720 [inline]
>>        balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911
>>        kswapd+0x5ea/0xbf0 mm/vmscan.c:7180
>>        kthread+0x2c1/0x3a0 kernel/kthread.c:389
>>        ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
>>        ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>>
>> -> #0 (fs_reclaim){+.+.}-{0:0}:
>>        check_prev_add kernel/locking/lockdep.c:3134 [inline]
>>        check_prevs_add kernel/locking/lockdep.c:3253 [inline]
>>        validate_chain kernel/locking/lockdep.c:3869 [inline]
>>        __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
>>        lock_acquire kernel/locking/lockdep.c:5754 [inline]
>>        lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
>>        __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
>>        fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
>>        might_alloc include/linux/sched/mm.h:334 [inline]
>>        slab_pre_alloc_hook mm/slub.c:3891 [inline]
>>        slab_alloc_node mm/slub.c:3981 [inline]
>>        __do_kmalloc_node mm/slub.c:4121 [inline]
>>        __kmalloc_noprof+0xb5/0x420 mm/slub.c:4135
>>        kmalloc_noprof include/linux/slab.h:664 [inline]
>>        kmalloc_array_noprof include/linux/slab.h:699 [inline]
>>        __exfat_get_dentry_set+0x81e/0xa90 fs/exfat/dir.c:816
>>        exfat_get_dentry_set+0x36/0x210 fs/exfat/dir.c:859
>>        exfat_get_uniname_from_ext_entry fs/exfat/dir.c:39 [inline]
>>        exfat_readdir+0x950/0x1520 fs/exfat/dir.c:155
>>        exfat_iterate+0x3c7/0xad0 fs/exfat/dir.c:261
>>        wrap_directory_iterator+0xa5/0xe0 fs/readdir.c:67
>>        iterate_dir+0x53e/0xb60 fs/readdir.c:110
>>        __do_sys_getdents64 fs/readdir.c:409 [inline]
>>        __se_sys_getdents64 fs/readdir.c:394 [inline]
>>        __ia32_sys_getdents64+0x14f/0x2e0 fs/readdir.c:394
>>        do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
>>        __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
>>        do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
>>        entry_SYSENTER_compat_after_hwframe+0x84/0x8e
>>
>> other info that might help us debug this:
>>
>>  Possible unsafe locking scenario:
>>
>>        CPU0                    CPU1
>>        ----                    ----
>>   lock(&sbi->s_lock#2);
>>                                lock(fs_reclaim);
>>                                lock(&sbi->s_lock#2);
>>   lock(fs_reclaim);
>>
>>  *** DEADLOCK ***
>>
>> 3 locks held by syz-executor.2/6265:
>>  #0: ffff88801db114c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xeb/0x180 fs/file.c:1191
>>  #1: ffff8880483da9e8 (&sb->s_type->i_mutex_key#24){++++}-{3:3}, at: wrap_directory_iterator+0x5a/0xe0 fs/readdir.c:56
>>  #2: ffff88804af1a0e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_iterate+0x33f/0xad0 fs/exfat/dir.c:256
>>
>> stack backtrace:
>> CPU: 0 PID: 6265 Comm: syz-executor.2 Not tainted 6.10.0-rc5-syzkaller-00018-g55027e689933 #0
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  __dump_stack lib/dump_stack.c:88 [inline]
>>  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
>>  check_noncircular+0x31a/0x400 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:3869 [inline]
>>  __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
>>  lock_acquire kernel/locking/lockdep.c:5754 [inline]
>>  lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
>>  __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
>>  fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
>>  might_alloc include/linux/sched/mm.h:334 [inline]
>>  slab_pre_alloc_hook mm/slub.c:3891 [inline]
>>  slab_alloc_node mm/slub.c:3981 [inline]
>>  __do_kmalloc_node mm/slub.c:4121 [inline]
>>  __kmalloc_noprof+0xb5/0x420 mm/slub.c:4135
>>  kmalloc_noprof include/linux/slab.h:664 [inline]
>>  kmalloc_array_noprof include/linux/slab.h:699 [inline]
>>  __exfat_get_dentry_set+0x81e/0xa90 fs/exfat/dir.c:816
>>  exfat_get_dentry_set+0x36/0x210 fs/exfat/dir.c:859
>>  exfat_get_uniname_from_ext_entry fs/exfat/dir.c:39 [inline]
>>  exfat_readdir+0x950/0x1520 fs/exfat/dir.c:155
>>  exfat_iterate+0x3c7/0xad0 fs/exfat/dir.c:261
>>  wrap_directory_iterator+0xa5/0xe0 fs/readdir.c:67
>>  iterate_dir+0x53e/0xb60 fs/readdir.c:110
>>  __do_sys_getdents64 fs/readdir.c:409 [inline]
>>  __se_sys_getdents64 fs/readdir.c:394 [inline]
>>  __ia32_sys_getdents64+0x14f/0x2e0 fs/readdir.c:394
>>  do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
>>  __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
>>  do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
>>  entry_SYSENTER_compat_after_hwframe+0x84/0x8e
>> RIP: 0023:0xf72f8579
>> Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
>> RSP: 002b:00000000f5ec95ac EFLAGS: 00000292 ORIG_RAX: 00000000000000dc
>> RAX: ffffffffffffffda RBX: 000000000000000a RCX: 0000000020002ec0
>> RDX: 0000000000001000 RSI: 0000000000000000 RDI: 0000000000000000
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
>> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>>  </TASK>
>> ----------------
>> Code disassembly (best guess), 2 bytes skipped:
>>    0:   10 06                   adc    %al,(%rsi)
>>    2:   03 74 b4 01             add    0x1(%rsp,%rsi,4),%esi
>>    6:   10 07                   adc    %al,(%rdi)
>>    8:   03 74 b0 01             add    0x1(%rax,%rsi,4),%esi
>>    c:   10 08                   adc    %cl,(%rax)
>>    e:   03 74 d8 01             add    0x1(%rax,%rbx,8),%esi
>>   1e:   00 51 52                add    %dl,0x52(%rcx)
>>   21:   55                      push   %rbp
>>   22:   89 e5                   mov    %esp,%ebp
>>   24:   0f 34                   sysenter
>>   26:   cd 80                   int    $0x80
>> * 28:   5d                      pop    %rbp <-- trapping instruction
>>   29:   5a                      pop    %rdx
>>   2a:   59                      pop    %rcx
>>   2b:   c3                      ret
>>   2c:   90                      nop
>>   2d:   90                      nop
>>   2e:   90                      nop
>>   2f:   90                      nop
>>   30:   8d b4 26 00 00 00 00    lea    0x0(%rsi,%riz,1),%esi
>>   37:   8d b4 26 00 00 00 00    lea    0x0(%rsi,%riz,1),%esi
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@...glegroups.com.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>>
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>>
>> If you want to undo deduplication, reply with:
>> #syz undup

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