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Message-ID: <eb8e5711-a7cd-4c69-9712-97b0cebfbc34@kernel.org>
Date: Tue, 4 Jun 2024 22:57:34 +0800
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Subject: Re: [syzbot] [exfat?] INFO: task hung in do_new_mount (2)
To: syzbot <syzbot+f59c2feaf7cb5988e877@syzkaller.appspotmail.com>,
 syzkaller-bugs@googlegroups.com
References: <00000000000093ea0d06142c361a@google.com>
Content-Language: en-US
From: Chao Yu <chao@kernel.org>
Cc: linkinjeon@kernel.org, sj1557.seo@samsung.com,
 linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
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#syz set subsystems: fs

On 2024/3/21 22:06, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=156b7946180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4d90a36f0cab495a
> dashboard link: https://syzkaller.appspot.com/bug?extid=f59c2feaf7cb5988e877
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1075d2c9180000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161012a5180000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f6c04726a2ae/disk-fe46a7dd.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/09c26ce901ea/vmlinux-fe46a7dd.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/134acf7f5322/bzImage-fe46a7dd.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/8eeb4ed4feec/mount_2.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f59c2feaf7cb5988e877@syzkaller.appspotmail.com
> 
> INFO: task syz-executor238:5068 blocked for more than 143 seconds.
>        Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor238 state:D stack:25616 pid:5068  tgid:5068  ppid:5063   flags:0x00004006
> Call Trace:
>   <TASK>
>   context_switch kernel/sched/core.c:5409 [inline]
>   __schedule+0x1781/0x49d0 kernel/sched/core.c:6736
>   __schedule_loop kernel/sched/core.c:6813 [inline]
>   schedule+0x14b/0x320 kernel/sched/core.c:6828
>   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6885
>   rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1178
>   __down_write_common+0x1af/0x200 kernel/locking/rwsem.c:1306
>   inode_lock include/linux/fs.h:793 [inline]
>   do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
>   lock_mount fs/namespace.c:2502 [inline]
>   do_new_mount_fc fs/namespace.c:3289 [inline]
>   do_new_mount+0x43d/0xb40 fs/namespace.c:3354
>   do_mount fs/namespace.c:3692 [inline]
>   __do_sys_mount fs/namespace.c:3898 [inline]
>   __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f180bc1f26a
> RSP: 002b:00007ffce5f8f508 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffce5f8f520 RCX: 00007f180bc1f26a
> RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007ffce5f8f520
> RBP: 0000000000000005 R08: 00007ffce5f8f560 R09: 00000000000014f8
> R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
> R13: 00007ffce5f8f560 R14: 0000000000000004 R15: 0000000000020000
>   </TASK>
> INFO: task syz-executor238:5071 blocked for more than 143 seconds.
>        Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor238 state:D stack:25336 pid:5071  tgid:5071  ppid:5066   flags:0x00004006
> Call Trace:
>   <TASK>
>   context_switch kernel/sched/core.c:5409 [inline]
>   __schedule+0x1781/0x49d0 kernel/sched/core.c:6736
>   __schedule_loop kernel/sched/core.c:6813 [inline]
>   schedule+0x14b/0x320 kernel/sched/core.c:6828
>   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6885
>   rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1178
>   __down_write_common+0x1af/0x200 kernel/locking/rwsem.c:1306
>   inode_lock include/linux/fs.h:793 [inline]
>   do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
>   lock_mount fs/namespace.c:2502 [inline]
>   do_new_mount_fc fs/namespace.c:3289 [inline]
>   do_new_mount+0x43d/0xb40 fs/namespace.c:3354
>   do_mount fs/namespace.c:3692 [inline]
>   __do_sys_mount fs/namespace.c:3898 [inline]
>   __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f180bc1f26a
> RSP: 002b:00007ffce5f8f508 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffce5f8f520 RCX: 00007f180bc1f26a
> RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007ffce5f8f520
> RBP: 0000000000000005 R08: 00007ffce5f8f560 R09: 00000000000014f8
> R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
> R13: 00007ffce5f8f560 R14: 0000000000000004 R15: 0000000000020000
>   </TASK>
> INFO: task syz-executor238:5073 blocked for more than 143 seconds.
>        Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor238 state:D stack:25456 pid:5073  tgid:5073  ppid:5069   flags:0x00004006
> Call Trace:
>   <TASK>
>   context_switch kernel/sched/core.c:5409 [inline]
>   __schedule+0x1781/0x49d0 kernel/sched/core.c:6736
>   __schedule_loop kernel/sched/core.c:6813 [inline]
>   schedule+0x14b/0x320 kernel/sched/core.c:6828
>   schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6885
>   rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1178
>   __down_write_common+0x1af/0x200 kernel/locking/rwsem.c:1306
>   inode_lock include/linux/fs.h:793 [inline]
>   do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
>   lock_mount fs/namespace.c:2502 [inline]
>   do_new_mount_fc fs/namespace.c:3289 [inline]
>   do_new_mount+0x43d/0xb40 fs/namespace.c:3354
>   do_mount fs/namespace.c:3692 [inline]
>   __do_sys_mount fs/namespace.c:3898 [inline]
>   __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f180bc1f26a
> RSP: 002b:00007ffce5f8f508 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffce5f8f520 RCX: 00007f180bc1f26a
> RDX: 0000000020001500 RSI: 0000000020000140 RDI: 00007ffce5f8f520
> RBP: 0000000000000005 R08: 00007ffce5f8f560 R09: 00000000000014f8
> R10: 0000000000000800 R11: 0000000000000286 R12: 0000000000000800
> R13: 00007ffce5f8f560 R14: 0000000000000004 R15: 0000000000020000
>   </TASK>
> 
> Showing all locks held in the system:
> 1 lock held by khungtaskd/29:
>   #0: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
>   #0: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
>   #0: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614
> 2 locks held by getty/4822:
>   #0: ffff88802a7690a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
>   #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2201
> 1 lock held by syz-executor238/5068:
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
> 3 locks held by syz-executor238/5072:
> 1 lock held by syz-executor238/5071:
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
> 1 lock held by syz-executor238/5073:
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
>   #0: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: do_lock_mount+0x112/0x3a0 fs/namespace.c:2460
> 2 locks held by syz-executor238/5141:
>   #0: ffff88801ff6efc8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x259/0x320 fs/file.c:1191
>   #1: ffff88807b2a02b8 (&sb->s_type->i_mutex_key#14){++++}-{3:3}, at: iterate_dir+0x436/0x6f0 fs/readdir.c:103
> 
> =============================================
> 
> NMI backtrace for cpu 0
> CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>   nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
>   nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
>   trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
>   check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
>   watchdog+0xfb0/0xff0 kernel/hung_task.c:379
>   kthread+0x2f0/0x390 kernel/kthread.c:388
>   ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
>   </TASK>
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1
> CPU: 1 PID: 5072 Comm: syz-executor238 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
> RIP: 0010:__sanitizer_cov_trace_cmp8+0x7d/0x90 kernel/kcov.c:285
> Code: c1 e1 05 48 8d 41 28 4c 39 c8 77 1e 49 ff c2 4c 89 12 48 c7 44 11 08 06 00 00 00 48 89 7c 11 10 48 89 74 11 18 4c 89 44 11 20 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90
> RSP: 0018:ffffc90004277398 EFLAGS: 00000093
> RAX: 0000000000000000 RBX: 00000000000000a0 RCX: ffff888011465a00
> RDX: ffff888011465a00 RSI: 00000000000000a0 RDI: 0000000000000080
> RBP: ffffc900042774e0 R08: ffffffff8217736e R09: 1ffffffff289d8e4
> R10: dffffc0000000000 R11: fffffbfff289d8e5 R12: ffff88807b1262b8
> R13: 0000000000039030 R14: 0000000000000000 R15: 0000000000000080
> FS:  00005555679ce380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f180361f000 CR3: 000000007721e000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <NMI>
>   </NMI>
>   <TASK>
>   lookup_bh_lru fs/buffer.c:1370 [inline]
>   __find_get_block+0x46e/0x10d0 fs/buffer.c:1397
>   bdev_getblk+0x38/0x610 fs/buffer.c:1423
>   __bread_gfp+0xac/0x430 fs/buffer.c:1474
>   sb_bread include/linux/buffer_head.h:321 [inline]
>   exfat_get_dentry+0x53b/0x730 fs/exfat/dir.c:770
>   exfat_readdir fs/exfat/dir.c:121 [inline]
>   exfat_iterate+0xbd7/0x33e0 fs/exfat/dir.c:261
>   wrap_directory_iterator+0x94/0xe0 fs/readdir.c:67
>   iterate_dir+0x539/0x6f0 fs/readdir.c:110
>   __do_sys_getdents64 fs/readdir.c:409 [inline]
>   __se_sys_getdents64+0x20d/0x4f0 fs/readdir.c:394
>   do_syscall_64+0xfb/0x240
>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
> RIP: 0033:0x7f180bc1ded9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffce5f8f698 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
> RAX: ffffffffffffffda RBX: 00007f180bc67082 RCX: 00007f180bc1ded9
> RDX: 0000000000000646 RSI: 0000000020000240 RDI: 0000000000000005
> RBP: 0030656c69662f2e R08: 00005555679cf378 R09: 00005555679cf378
> R10: 00000000000014f8 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007ffce5f8f6d0 R14: 00007ffce5f8f6bc R15: 00007f180bc6703b
>   </TASK>
> INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.453 msecs
> 
> 
> ---
> 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@googlegroups.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 syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> 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