[syzbot] [ext4?] INFO: task hung in lock_two_directories (4)

[syzbot <syzbot+1bfacdf603474cfa86bd@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    a5806cd506af Linux 6.15-rc7
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10defef4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3340af1a8845dd35
dashboard link: https://syzkaller.appspot.com/bug?extid=1bfacdf603474cfa86bd
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14f292d4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14e29e70580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/652000eacd92/disk-a5806cd5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b445a74e31e/vmlinux-a5806cd5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0a4ef01f165f/bzImage-a5806cd5.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/6f80bf89f51a/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10f7c1f4580000)

The issue was bisected to:

commit e63d86b8b76437815fc040e8e65da257c28ba922
Author: Roberto Sassu <roberto.sassu@huawei.com>
Date:   Thu Nov 16 09:01:24 2023 +0000

    smack: Initialize the in-memory inode in smack_inode_init_security()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=148852d4580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=168852d4580000
console output: https://syzkaller.appspot.com/x/log.txt?x=128852d4580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bfacdf603474cfa86bd@syzkaller.appspotmail.com
Fixes: e63d86b8b764 ("smack: Initialize the in-memory inode in smack_inode_init_security()")

INFO: task syz-executor125:5853 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor125 state:D stack:28616 pid:5853  tgid:5847  ppid:5846   task_flags:0x400040 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x168f/0x4c70 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 rwsem_down_write_slowpath+0xbec/0x1030 kernel/locking/rwsem.c:1176
 __down_write_common kernel/locking/rwsem.c:1304 [inline]
 __down_write kernel/locking/rwsem.c:1313 [inline]
 down_write_nested+0x1b5/0x200 kernel/locking/rwsem.c:1694
 inode_lock_nested include/linux/fs.h:902 [inline]
 lock_two_directories+0x16b/0x220 fs/namei.c:3236
 lock_rename fs/namei.c:3270 [inline]
 do_renameat2+0x38a/0xc50 fs/namei.c:5216
 __do_sys_rename fs/namei.c:5317 [inline]
 __se_sys_rename fs/namei.c:5315 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5315
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f58ce457489
RSP: 002b:00007f58ce3ea168 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f58ce4de6b8 RCX: 00007f58ce457489
RDX: 0030656c69662f30 RSI: 00002000000001c0 RDI: 0000200000000000
RBP: 00007f58ce4de6b0 R08: 00007ffff522f7d7 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f58ce4de6bc
R13: 000000000000006e R14: 00007ffff522f6f0 R15: 00007ffff522f7d8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6764
2 locks held by getty/5581:
 #0: ffff88814cb7c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900030062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
3 locks held by syz-executor125/5849:
4 locks held by syz-executor125/5853:
 #0: ffff8880353d6420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:556
 #1: ffff8880353d6730 (&type->s_vfs_rename_key){+.+.}-{4:4}, at: lock_rename fs/namei.c:3269 [inline]
 #1: ffff8880353d6730 (&type->s_vfs_rename_key){+.+.}-{4:4}, at: do_renameat2+0x37f/0xc50 fs/namei.c:5216
 #2: ffff88807b085d60 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:902 [inline]
 #2: ffff88807b085d60 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: lock_two_directories+0x141/0x220 fs/namei.c:3235
 #3: ffff88807b329808 (&type->i_mutex_dir_key#3/5){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:902 [inline]
 #3: ffff88807b329808 (&type->i_mutex_dir_key#3/5){+.+.}-{4:4}, at: lock_two_directories+0x16b/0x220 fs/namei.c:3236

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc7-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:437
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5849 Comm: syz-executor125 Not tainted 6.15.0-rc7-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x8/0x90 kernel/kcov.c:321
Code: 48 89 44 11 20 c3 cc cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 a0 72 92 65 8b 15 58 aa b2 10 81 e2 00 01 ff 00
RSP: 0018:ffffc900044d6ef8 EFLAGS: 00000246
RAX: ffffffff826f434a RBX: 1ffff9200089adf8 RCX: ffffffff826f431d
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900044d7090 R08: ffff8880778b39ff R09: 1ffff1100ef1673f
R10: dffffc0000000000 R11: ffffed100ef16740 R12: 000000000000000e
R13: 1ffff1100ef1673f R14: 000000000000601b R15: ffff8880778b39f8
FS:  00007f58ce40b6c0(0000) GS:ffff8881261f6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d3b19b24b0 CR3: 0000000034b24000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_buffer_uptodate fs/ext4/ext4.h:3842 [inline]
 __ext4_get_inode_loc+0x5aa/0x1040 fs/ext4/inode.c:4458
 ext4_get_inode_loc fs/ext4/inode.c:4583 [inline]
 ext4_reserve_inode_write+0x191/0x330 fs/ext4/inode.c:5889
 __ext4_mark_inode_dirty+0x15b/0x700 fs/ext4/inode.c:6066
 ext4_dirty_inode+0xd0/0x110 fs/ext4/inode.c:6103
 __mark_inode_dirty+0x2d1/0xdf0 fs/fs-writeback.c:2527
 mark_inode_dirty include/linux/fs.h:2545 [inline]
 dquot_alloc_space include/linux/quotaops.h:319 [inline]
 dquot_alloc_block include/linux/quotaops.h:336 [inline]
 ext4_xattr_block_set+0x12ca/0x2ac0 fs/ext4/xattr.c:2048
 ext4_xattr_set_handle+0xdfb/0x1590 fs/ext4/xattr.c:2447
 ext4_initxattrs+0x9f/0x110 fs/ext4/xattr_security.c:44
 security_inode_init_security+0x2a0/0x3f0 security/security.c:1852
 __ext4_new_inode+0x3257/0x3bd0 fs/ext4/ialloc.c:1326
 ext4_create+0x22d/0x460 fs/ext4/namei.c:2824
 lookup_open fs/namei.c:3701 [inline]
 open_last_lookups fs/namei.c:3800 [inline]
 path_openat+0x14f1/0x3830 fs/namei.c:4036
 do_filp_open+0x1fa/0x410 fs/namei.c:4066
 do_sys_openat2+0x121/0x1c0 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1455
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f58ce457489
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 18 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:00007f58ce40b168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f58ce4de6a8 RCX: 00007f58ce457489
RDX: 0000000000101042 RSI: 0000200000000140 RDI: 00000000ffffff9c
RBP: 00007f58ce4de6a0 R08: 00007f58ce40b6c0 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00007f58ce4de6ac
R13: 0000000000000006 R14: 00007ffff522f6f0 R15: 00007ffff522f7d8
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.394 msecs


---
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