syzbot

loop0: detected capacity change from 0 to 512
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/4493 is trying to acquire lock:
ffff88801ef10bd8 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689

but task is already holding lock:
ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_trylock_xattr fs/ext4/xattr.h:162 [inline]
ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: ext4_try_to_expand_extra_isize fs/ext4/inode.c:5941 [inline]
ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: __ext4_mark_inode_dirty+0x3e8/0x700 fs/ext4/inode.c:6022

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&ei->xattr_sem){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ext4_setattr+0x71d/0x19e0 fs/ext4/inode.c:5465
       notify_change+0xbcd/0xee0 fs/attr.c:505
       chown_common+0x483/0x610 fs/open.c:680
       do_fchownat+0x164/0x270 fs/open.c:711
       __do_sys_chown fs/open.c:731 [inline]
       __se_sys_chown fs/open.c:729 [inline]
       __x64_sys_chown+0x7e/0x90 fs/open.c:729
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0x1338/0x15a0 fs/jbd2/transaction.c:464
       jbd2__journal_start+0x2b7/0x5a0 fs/jbd2/transaction.c:521
       __ext4_journal_start_sb+0x167/0x360 fs/ext4/ext4_jbd2.c:105
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_writepages+0xdc2/0x2d20 fs/ext4/inode.c:2812
       do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
       filemap_fdatawrite_wbc+0x1eb/0x240 mm/filemap.c:400
       __filemap_fdatawrite_range mm/filemap.c:433 [inline]
       file_write_and_wait_range+0x129/0x1e0 mm/filemap.c:810
       ext4_sync_file+0x1ff/0xae0 fs/ext4/fsync.c:151
       vfs_fsync_range fs/sync.c:188 [inline]
       vfs_fsync fs/sync.c:202 [inline]
       do_fsync fs/sync.c:212 [inline]
       __do_sys_fsync fs/sync.c:220 [inline]
       __se_sys_fsync fs/sync.c:218 [inline]
       __x64_sys_fsync+0x1a5/0x1e0 fs/sync.c:218
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&sbi->s_writepages_rwsem){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       percpu_down_read+0x46/0x1b0 include/linux/percpu-rwsem.h:51
       ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689
       do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
       __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
       writeback_single_inode+0x221/0x8b0 fs/fs-writeback.c:1770
       write_inode_now+0x217/0x280 fs/fs-writeback.c:2811
       iput_final fs/inode.c:1756 [inline]
       iput+0x5ab/0x8a0 fs/inode.c:1795
       ext4_xattr_set_entry+0x10ff/0x3d30 fs/ext4/xattr.c:1837
       ext4_xattr_block_set+0x4f7/0x2d30 fs/ext4/xattr.c:1936
       ext4_xattr_move_to_block fs/ext4/xattr.c:2633 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2708 [inline]
       ext4_expand_extra_isize_ea+0xf4b/0x19a0 fs/ext4/xattr.c:2800
       __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:5901
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5944 [inline]
       __ext4_mark_inode_dirty+0x469/0x700 fs/ext4/inode.c:6022
       ext4_evict_inode+0xa81/0x1080 fs/ext4/inode.c:282
       evict+0x485/0x870 fs/inode.c:647
       ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:470
       ext4_fill_super+0x92f0/0x9a60 fs/ext4/super.c:4975
       mount_bdev+0x287/0x3c0 fs/super.c:1400
       legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1530
       do_new_mount+0x24a/0xa40 fs/namespace.c:3034
       do_mount fs/namespace.c:3377 [inline]
       __do_sys_mount fs/namespace.c:3585 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  &sbi->s_writepages_rwsem --> jbd2_handle --> &ei->xattr_sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->xattr_sem);
                               lock(jbd2_handle);
                               lock(&ei->xattr_sem);
  lock(&sbi->s_writepages_rwsem);

 *** DEADLOCK ***

3 locks held by syz.0.17/4493:
 #0: ffff888075b500e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
 #1: ffff888075b50650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
 #1: ffff888075b50650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1928 [inline]
 #1: ffff888075b50650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x444/0x1080 fs/ext4/inode.c:243
 #2: ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_trylock_xattr fs/ext4/xattr.h:162 [inline]
 #2: ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: ext4_try_to_expand_extra_isize fs/ext4/inode.c:5941 [inline]
 #2: ffff88806f704690 (&ei->xattr_sem){++++}-{3:3}, at: __ext4_mark_inode_dirty+0x3e8/0x700 fs/ext4/inode.c:6022

stack backtrace:
CPU: 1 PID: 4493 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 percpu_down_read+0x46/0x1b0 include/linux/percpu-rwsem.h:51
 ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689
 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
 writeback_single_inode+0x221/0x8b0 fs/fs-writeback.c:1770
 write_inode_now+0x217/0x280 fs/fs-writeback.c:2811
 iput_final fs/inode.c:1756 [inline]
 iput+0x5ab/0x8a0 fs/inode.c:1795
 ext4_xattr_set_entry+0x10ff/0x3d30 fs/ext4/xattr.c:1837
 ext4_xattr_block_set+0x4f7/0x2d30 fs/ext4/xattr.c:1936
 ext4_xattr_move_to_block fs/ext4/xattr.c:2633 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2708 [inline]
 ext4_expand_extra_isize_ea+0xf4b/0x19a0 fs/ext4/xattr.c:2800
 __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:5901
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5944 [inline]
 __ext4_mark_inode_dirty+0x469/0x700 fs/ext4/inode.c:6022
 ext4_evict_inode+0xa81/0x1080 fs/ext4/inode.c:282
 evict+0x485/0x870 fs/inode.c:647
 ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:470
 ext4_fill_super+0x92f0/0x9a60 fs/ext4/super.c:4975
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f85b7ed7eea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3f09d538 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe3f09d5c0 RCX: 00007f85b7ed7eea
RDX: 00002000000002c0 RSI: 00002000000001c0 RDI: 00007ffe3f09d580
RBP: 00002000000002c0 R08: 00007ffe3f09d5c0 R09: 0000000000800700
R10: 0000000000800700 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007ffe3f09d580 R14: 000000000000046f R15: 000000000000002c
 </TASK>
------------[ cut here ]------------
EA inode 11 i_nlink=2
WARNING: CPU: 0 PID: 4493 at fs/ext4/xattr.c:1022 ext4_xattr_inode_update_ref+0x4be/0x520 fs/ext4/xattr.c:1020
Modules linked in:
CPU: 0 PID: 4493 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:ext4_xattr_inode_update_ref+0x4be/0x520 fs/ext4/xattr.c:1020
Code: 8d 7d 40 4c 89 f8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ff e8 a3 df a2 ff 49 8b 37 48 c7 c7 c0 8c 1d 8a 89 da e8 d2 d2 7d 07 <0f> 0b 49 be 00 00 00 00 00 fc ff df 4c 8b 6c 24 10 4c 8b 7c 24 08
RSP: 0018:ffffc9000326f140 EFLAGS: 00010246
RAX: b4eb95dff0df9a00 RBX: 0000000000000002 RCX: ffff888079bb3b80
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000326f230 R08: dffffc0000000000 R09: ffffed1017204f2c
R10: ffffed1017204f2c R11: 1ffff11017204f2b R12: ffffc9000326f1a0
R13: ffff88805c061690 R14: dffffc0000000000 R15: ffff88805c0616d0
FS:  0000555564cd8500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cfb3f00950 CR3: 0000000024b15000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_xattr_inode_dec_ref fs/ext4/xattr.c:1045 [inline]
 ext4_xattr_set_entry+0xed0/0x3d30 fs/ext4/xattr.c:1697
 ext4_xattr_ibody_set+0x112/0x330 fs/ext4/xattr.c:2253
 ext4_xattr_move_to_block fs/ext4/xattr.c:2640 [inline]
 ext4_xattr_make_inode_space fs/ext4/xattr.c:2708 [inline]
 ext4_expand_extra_isize_ea+0xf9a/0x19a0 fs/ext4/xattr.c:2800
 __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:5901
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5944 [inline]
 __ext4_mark_inode_dirty+0x469/0x700 fs/ext4/inode.c:6022
 ext4_evict_inode+0xa81/0x1080 fs/ext4/inode.c:282
 evict+0x485/0x870 fs/inode.c:647
 ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:470
 ext4_fill_super+0x92f0/0x9a60 fs/ext4/super.c:4975
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f85b7ed7eea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3f09d538 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe3f09d5c0 RCX: 00007f85b7ed7eea
RDX: 00002000000002c0 RSI: 00002000000001c0 RDI: 00007ffe3f09d580
RBP: 00002000000002c0 R08: 00007ffe3f09d5c0 R09: 0000000000800700
R10: 0000000000800700 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007ffe3f09d580 R14: 000000000000046f R15: 000000000000002c
 </TASK>