[v6.1] possible deadlock in __ocfs2_reflink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12d8a2c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=508551fa033c2f3af4e6
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/7cd9b1875376/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b5d35d18c31/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d5ee64c2af77/Image-e4f7d8be.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+508551...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.625/6941 is trying to acquire lock:
ffff0000f5edd108 (&sb->s_type->i_mutex_key#29/2){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
ffff0000f5edd108 (&sb->s_type->i_mutex_key#29/2){+.+.}-{3:3}, at: __ocfs2_reflink+0x9c0/0x136c fs/ocfs2/refcounttree.c:4178

but task is already holding lock:
ffff0000f5eddbe0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x484/0x84c fs/ocfs2/refcounttree.c:4276

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
down_read+0x64/0x300 kernel/locking/rwsem.c:1520
ocfs2_inode_lock_for_extent_tree+0xec/0x268 fs/ocfs2/file.c:2210
ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2266 [inline]
ocfs2_file_write_iter+0x5bc/0x1cd0 fs/ocfs2/file.c:2451
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x3c8/0x7c8 fs/read_write.c:584
ksys_write+0x12c/0x228 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__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

-> #1 (&sb->s_type->i_mutex_key#29){+.+.}-{3:3}:
down_write+0x5c/0x88 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:758 [inline]
vfs_rename+0x6a8/0xe3c fs/namei.c:4847
do_renameat2+0x760/0xaa4 fs/namei.c:5035
__do_sys_renameat2 fs/namei.c:5068 [inline]
__se_sys_renameat2 fs/namei.c:5065 [inline]
__arm64_sys_renameat2+0xe8/0x104 fs/namei.c:5065
__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 (&sb->s_type->i_mutex_key#29/2){+.+.}-{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_nested+0x64/0x94 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:793 [inline]
__ocfs2_reflink+0x9c0/0x136c fs/ocfs2/refcounttree.c:4178
ocfs2_reflink+0x498/0x84c fs/ocfs2/refcounttree.c:4277
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:
&sb->s_type->i_mutex_key#29/2 --> &sb->s_type->i_mutex_key#29 --> &ocfs2_file_ip_alloc_sem_key

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&ocfs2_file_ip_alloc_sem_key);
lock(&sb->s_type->i_mutex_key#29);
lock(&ocfs2_file_ip_alloc_sem_key);
lock(&sb->s_type->i_mutex_key#29/2);

*** DEADLOCK ***

5 locks held by syz.5.625/6941:
#0: ffff0000d9dd2460 (sb_writers#26){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:402
#1: ffff0000e16db488 (&type->i_mutex_dir_key#15/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
#1: ffff0000e16db488 (&type->i_mutex_dir_key#15/1){+.+.}-{3:3}, at: filename_create+0x1b0/0x3a8 fs/namei.c:3884
#2: ffff0000f5eddf48 (&sb->s_type->i_mutex_key#29){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
#2: ffff0000f5eddf48 (&sb->s_type->i_mutex_key#29){+.+.}-{3:3}, at: ocfs2_vfs_reflink+0x2bc/0x400 fs/ocfs2/refcounttree.c:4400
#3: ffff0000f5eddc78 (&oi->ip_xattr_sem){++++}-{3:3}, at: ocfs2_reflink+0x47c/0x84c fs/ocfs2/refcounttree.c:4275
#4: ffff0000f5eddbe0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_reflink+0x484/0x84c fs/ocfs2/refcounttree.c:4276

stack backtrace:
CPU: 1 PID: 6941 Comm: syz.5.625 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_nested+0x64/0x94 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:793 [inline]
__ocfs2_reflink+0x9c0/0x136c fs/ocfs2/refcounttree.c:4178
ocfs2_reflink+0x498/0x84c fs/ocfs2/refcounttree.c:4277
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
(syz.5.625,6941,1):ocfs2_check_dir_entry:325 ERROR: bad entry in directory #72: rec_len is smaller than minimal - offset=0, inode=1099511627848, rec_len=12, name_len=0
(syz.5.625,6941,1):__ocfs2_delete_entry:1162 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_orphan_del:2386 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_orphan_del:2401 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_mv_orphaned_inode_to_new:2860 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_mv_orphaned_inode_to_new:2906 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_reflink:4310 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_check_dir_entry:325 ERROR: bad entry in directory #72: rec_len is smaller than minimal - offset=0, inode=1099511627848, rec_len=12, name_len=0
(syz.5.625,6941,1):__ocfs2_delete_entry:1162 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_orphan_del:2386 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_orphan_del:2401 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_remove_inode:709 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_wipe_inode:854 ERROR: status = -5
(syz.5.625,6941,1):ocfs2_delete_inode:1115 ERROR: status = -5


---
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