[v6.1] possible deadlock in ocfs2_reflink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 090666d3cc90 Linux 6.1.177
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1778c232580000
kernel config: https://syzkaller.appspot.com/x/.config?x=cd374bd3b354feae
dashboard link: https://syzkaller.appspot.com/bug?extid=a23565fe695ce2cb9a77
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/378e2dbb7ed4/disk-090666d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/48878db70015/vmlinux-090666d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/31993c027dae/Image-090666d3.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a23565...@syzkaller.appspotmail.com

JBD2: Ignoring recovery information on journal
ocfs2: Mounting device (7,7) on (node local, slot 0) with ordered data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.7.1817/9335 is trying to acquire lock:
ffff0000d68bdbe0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x484/0x84c fs/ocfs2/refcounttree.c:4276

but task is already holding lock:
ffff0000d68bdc78 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x47c/0x84c fs/ocfs2/refcounttree.c:4275

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&oi->ip_xattr_sem){++++}-{3:3}:
down_read+0x64/0x300 kernel/locking/rwsem.c:1520
ocfs2_init_acl+0x264/0x61c fs/ocfs2/acl.c:365
ocfs2_mknod+0x12b0/0x218c fs/ocfs2/namei.c:410
ocfs2_create+0x19c/0x51c fs/ocfs2/namei.c:674
lookup_open fs/namei.c:3490 [inline]
open_last_lookups fs/namei.c:3558 [inline]
path_openat+0xda8/0x27a0 fs/namei.c:3788
do_filp_open+0x198/0x38c fs/namei.c:3818
do_sys_openat2+0x134/0x3fc fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__arm64_sys_openat+0x11c/0x150 fs/open.c:1347
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #2 (&journal->j_trans_barrier){.+.+}-{3:3}:
down_read+0x64/0x300 kernel/locking/rwsem.c:1520
ocfs2_start_trans+0x38c/0x6f4 fs/ocfs2/journal.c:374
ocfs2_shutdown_local_alloc+0x1a0/0x858 fs/ocfs2/localalloc.c:416
ocfs2_dismount_volume+0x1f4/0x95c fs/ocfs2/super.c:1882
ocfs2_put_super+0x108/0x390 fs/ocfs2/super.c:1609
generic_shutdown_super+0x138/0x32c fs/super.c:501
kill_block_super+0x78/0xe0 fs/super.c:1470
deactivate_locked_super+0xb4/0x128 fs/super.c:332
deactivate_super+0xe4/0x104 fs/super.c:363
cleanup_mnt+0x3a8/0x430 fs/namespace.c:1191
__cleanup_mnt+0x20/0x30 fs/namespace.c:1198
task_work_run+0x1f4/0x280 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x20f8/0x2c84 arch/arm64/kernel/signal.c:1151
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #1 (sb_internal#2){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1891 [inline]
sb_start_intwrite include/linux/fs.h:2013 [inline]
ocfs2_start_trans+0x20c/0x6f4 fs/ocfs2/journal.c:372
ocfs2_setattr+0xe68/0x1950 fs/ocfs2/file.c:1251
notify_change+0xb5c/0xe20 fs/attr.c:499
chown_common+0x430/0x59c fs/open.c:736
vfs_fchown fs/open.c:804 [inline]
ksys_fchown+0xe0/0x158 fs/open.c:815
__do_sys_fchown fs/open.c:823 [inline]
__se_sys_fchown fs/open.c:821 [inline]
__arm64_sys_fchown+0x7c/0x94 fs/open.c:821
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3830 [inline]
__lock_acquire+0x2808/0x6634 kernel/locking/lockdep.c:5063
lock_acquire+0x20c/0x638 kernel/locking/lockdep.c:5676
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
ocfs2_reflink+0x484/0x84c fs/ocfs2/refcounttree.c:4276
ocfs2_vfs_reflink+0x300/0x400 fs/ocfs2/refcounttree.c:4403
ocfs2_reflink_ioctl+0x35c/0x3f0 fs/ocfs2/refcounttree.c:4443
ocfs2_ioctl+0x884/0xb2c fs/ocfs2/ioctl.c:913
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

Chain exists of:
&ocfs2_file_ip_alloc_sem_key --> &journal->j_trans_barrier --> &oi->ip_xattr_sem

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&oi->ip_xattr_sem);
lock(&journal->j_trans_barrier);
lock(&oi->ip_xattr_sem);
lock(&ocfs2_file_ip_alloc_sem_key);

*** DEADLOCK ***

4 locks held by syz.7.1817/9335:
#0: ffff0000ff3c8460 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:402
#1: ffff0000e15f3488 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
#1: ffff0000e15f3488 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: filename_create+0x1b0/0x3a8 fs/namei.c:3884
#2: ffff0000d68bdf48 (&sb->s_type->i_mutex_key#31){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#2: ffff0000d68bdf48 (&sb->s_type->i_mutex_key#31){+.+.}-{3:3}, at: ocfs2_vfs_reflink+0x2bc/0x400 fs/ocfs2/refcounttree.c:4400
#3: ffff0000d68bdc78 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x47c/0x84c fs/ocfs2/refcounttree.c:4275

stack backtrace:
CPU: 1 PID: 9335 Comm: syz.7.1817 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack+0x30/0x40 lib/dump_stack.c:88
dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
dump_stack+0x1c/0x5c lib/dump_stack.c:113
print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2048
check_noncircular+0x264/0x2f8 kernel/locking/lockdep.c:2170
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3830 [inline]
__lock_acquire+0x2808/0x6634 kernel/locking/lockdep.c:5063
lock_acquire+0x20c/0x638 kernel/locking/lockdep.c:5676
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
ocfs2_reflink+0x484/0x84c fs/ocfs2/refcounttree.c:4276
ocfs2_vfs_reflink+0x300/0x400 fs/ocfs2/refcounttree.c:4403
ocfs2_reflink_ioctl+0x35c/0x3f0 fs/ocfs2/refcounttree.c:4443
ocfs2_ioctl+0x884/0xb2c fs/ocfs2/ioctl.c:913
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585


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