[v6.1] INFO: task hung in do_renameat2 (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7b34dc04e4ff Linux 6.1.154
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16168942580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=8bb30c20d269eeadd9b3
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1f1ed5df43e0/disk-7b34dc04.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/941b7c0f58be/vmlinux-7b34dc04.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6fb9bad299e4/bzImage-7b34dc04.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8bb30c...@syzkaller.appspotmail.com

INFO: task syz.0.1732:9319 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1732 state:D stack:27904 pid:9319 ppid:4268 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
rwsem_down_write_slowpath+0xbed/0x1090 kernel/locking/rwsem.c:1189
lock_rename include/linux/fs.h:-1 [inline]
do_renameat2+0x423/0xc70 fs/namei.c:4966
__do_sys_renameat2 fs/namei.c:5060 [inline]
__se_sys_renameat2 fs/namei.c:5057 [inline]
__x64_sys_renameat2+0xce/0xe0 fs/namei.c:5057
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f059078eec9
RSP: 002b:00007f0591653038 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 00007f05909e6090 RCX: 00007f059078eec9
RDX: 0000000000000004 RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007f0590811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000200 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f05909e6128 R14: 00007f05909e6090 R15: 00007ffd927732b8
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8cb2b570 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8cb2bd90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
#0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by getty/4030:
#0: ffff88814d136098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
3 locks held by syz.0.1732/9310:
2 locks held by syz.0.1732/9319:
#0: ffff888024624460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:393
#1: ffff888051c42218 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: lock_rename include/linux/fs.h:-1 [inline]
#1: ffff888051c42218 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_renameat2+0x423/0xc70 fs/namei.c:4966
2 locks held by ext4lazyinit/9312:
1 lock held by syz-executor/10888:
#0: ffff888024aac0e0 (&type->s_umount_key#70){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xeee/0xf30 kernel/hung_task.c:377
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9312 Comm: ext4lazyinit Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:check_preemption_disabled+0x1/0x110 lib/smp_processor_id.c:13
Code: 20 74 bc 8c 4c 89 f6 e8 fd 1c 17 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 80 fc de 8a 48 c7 c6 c0 fc de 8a eb 00 55 <41> 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24
RSP: 0018:ffffc9001745fa10 EFLAGS: 00000282
RAX: ffffffff81aa4025 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff888053a5bb80 RSI: ffffffff8adefcc0 RDI: ffffffff8adefc80
RBP: ffffc9001745fb58 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 0000000000000007
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff888140d33f00
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fce9687c000 CR3: 0000000049f7e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:721
rcu_read_lock include/linux/rcupdate.h:792 [inline]
mapping_get_entry mm/filemap.c:1878 [inline]
__filemap_get_folio+0x12e/0xdd0 mm/filemap.c:1943
pagecache_get_page+0x26/0x250 mm/folio-compat.c:110
find_or_create_page include/linux/pagemap.h:646 [inline]
grow_dev_page fs/buffer.c:946 [inline]
grow_buffers fs/buffer.c:1011 [inline]
__getblk_slow fs/buffer.c:1038 [inline]
__getblk_gfp+0x2d8/0xb20 fs/buffer.c:1333
sb_getblk include/linux/buffer_head.h:356 [inline]
ext4_read_block_bitmap_nowait+0x1fb/0x960 fs/ext4/balloc.c:482
ext4_mb_prefetch+0x440/0x620 fs/ext4/mballoc.c:2582
ext4_run_li_request fs/ext4/super.c:3654 [inline]
ext4_lazyinit_thread+0x749/0x1800 fs/ext4/super.c:3780
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>


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