syzbot
possible deadlock in delete_one_xattr
Status:
upstream: reported on 2026/09/22 08:06
Reported-by: syzbot+3c4db27049db1f2ba938@syzkaller.appspotmail.com
First crash: 16d, last: 13h13m
Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1018/9520 is trying to acquire lock:
ffff88805c18a410 (&type->i_mutex_dir_key#15/2){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
ffff88805c18a410 (&type->i_mutex_dir_key#15/2){+.+.}-{3:3}, at: xattr_rmdir fs/reiserfs/xattr.c:107 [inline]
ffff88805c18a410 (&type->i_mutex_dir_key#15/2){+.+.}-{3:3}, at: delete_one_xattr+0xfa/0x2d0 fs/reiserfs/xattr.c:339
but task is already holding lock:
ffff88805c189d70 (&type->i_mutex_dir_key#15/3){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
ffff88805c189d70 (&type->i_mutex_dir_key#15/3){+.+.}-{3:3}, at: reiserfs_for_each_xattr+0x89a/0xa30 fs/reiserfs/xattr.c:310
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&type->i_mutex_dir_key#15/3){+.+.}-{3:3}:
down_write_nested+0x9e/0x200 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:839 [inline]
open_xa_root fs/reiserfs/xattr.c:128 [inline]
open_xa_dir+0x146/0x6f0 fs/reiserfs/xattr.c:153
xattr_lookup+0x22/0x2a0 fs/reiserfs/xattr.c:396
reiserfs_xattr_set_handle+0x11a/0xd10 fs/reiserfs/xattr.c:535
reiserfs_xattr_set+0x47b/0x5b0 fs/reiserfs/xattr.c:635
__vfs_setxattr+0x437/0x470 fs/xattr.c:201
__vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:235
vfs_setxattr+0x16b/0x2f0 fs/xattr.c:322
do_setxattr fs/xattr.c:630 [inline]
path_setxattr+0x33a/0x590 fs/xattr.c:659
__do_sys_lsetxattr fs/xattr.c:684 [inline]
__se_sys_lsetxattr fs/xattr.c:680 [inline]
__x64_sys_lsetxattr+0xb8/0xd0 fs/xattr.c:680
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #1 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}:
down_write+0x97/0x200 kernel/locking/rwsem.c:1573
inode_lock include/linux/fs.h:804 [inline]
vfs_rename+0x6f4/0xe60 fs/namei.c:-1
do_renameat2+0x8b0/0xc80 fs/namei.c:5080
__do_sys_renameat2 fs/namei.c:5113 [inline]
__se_sys_renameat2 fs/namei.c:5110 [inline]
__x64_sys_renameat2+0xd2/0xe0 fs/namei.c:5110
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #0 (&type->i_mutex_dir_key#15/2){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3162 [inline]
check_prevs_add kernel/locking/lockdep.c:3281 [inline]
validate_chain kernel/locking/lockdep.c:3897 [inline]
__lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
down_write_nested+0x9e/0x200 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:839 [inline]
xattr_rmdir fs/reiserfs/xattr.c:107 [inline]
delete_one_xattr+0xfa/0x2d0 fs/reiserfs/xattr.c:339
reiserfs_for_each_xattr+0x8a6/0xa30 fs/reiserfs/xattr.c:312
reiserfs_delete_xattrs+0x20/0x90 fs/reiserfs/xattr.c:365
reiserfs_evict_inode+0x24a/0x4c0 fs/reiserfs/inode.c:53
evict+0x4b7/0x8a0 fs/inode.c:705
d_delete_notify include/linux/fsnotify.h:269 [inline]
vfs_rmdir+0x378/0x4b0 fs/namei.c:4264
do_rmdir+0x29f/0x590 fs/namei.c:4310
__do_sys_unlinkat fs/namei.c:4488 [inline]
__se_sys_unlinkat fs/namei.c:4482 [inline]
__x64_sys_unlinkat+0xc4/0xe0 fs/namei.c:4482
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
other info that might help us debug this:
Chain exists of:
&type->i_mutex_dir_key#15/2 --> &sb->s_type->i_mutex_key#30 --> &type->i_mutex_dir_key#15/3
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#15/3);
lock(&sb->s_type->i_mutex_key#30);
lock(&type->i_mutex_dir_key#15/3);
lock(&type->i_mutex_dir_key#15/2);
*** DEADLOCK ***
3 locks held by syz.4.1018/9520:
#0: ffff888058c3c418 (sb_writers#24){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
#1: ffff88805e7fd910 (&type->i_mutex_dir_key#15/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
#1: ffff88805e7fd910 (&type->i_mutex_dir_key#15/1){+.+.}-{3:3}, at: do_rmdir+0x1c6/0x590 fs/namei.c:4298
#2: ffff88805c189d70 (&type->i_mutex_dir_key#15/3){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
#2: ffff88805c189d70 (&type->i_mutex_dir_key#15/3){+.+.}-{3:3}, at: reiserfs_for_each_xattr+0x89a/0xa30 fs/reiserfs/xattr.c:310
stack backtrace:
CPU: 1 PID: 9520 Comm: syz.4.1018 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2215
check_prev_add kernel/locking/lockdep.c:3162 [inline]
check_prevs_add kernel/locking/lockdep.c:3281 [inline]
validate_chain kernel/locking/lockdep.c:3897 [inline]
__lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
down_write_nested+0x9e/0x200 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:839 [inline]
xattr_rmdir fs/reiserfs/xattr.c:107 [inline]
delete_one_xattr+0xfa/0x2d0 fs/reiserfs/xattr.c:339
reiserfs_for_each_xattr+0x8a6/0xa30 fs/reiserfs/xattr.c:312
reiserfs_delete_xattrs+0x20/0x90 fs/reiserfs/xattr.c:365
reiserfs_evict_inode+0x24a/0x4c0 fs/reiserfs/inode.c:53
evict+0x4b7/0x8a0 fs/inode.c:705
d_delete_notify include/linux/fsnotify.h:269 [inline]
vfs_rmdir+0x378/0x4b0 fs/namei.c:4264
do_rmdir+0x29f/0x590 fs/namei.c:4310
__do_sys_unlinkat fs/namei.c:4488 [inline]
__se_sys_unlinkat fs/namei.c:4482 [inline]
__x64_sys_unlinkat+0xc4/0xe0 fs/namei.c:4482
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f549299e199
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5490bf6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f5492c25fa0 RCX: 00007f549299e199
RDX: 0000000000000200 RSI: 00002000000001c0 RDI: ffffffffffffff9c
RBP: 00007f5492a35888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5492c26038 R14: 00007f5492c25fa0 R15: 00007ffc272afeb8
</TASK>
* Struck through repros no longer work on HEAD.