syzbot

EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
ext4 filesystem being mounted at /396/file1 supports timestamps until 2038-01-19 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.2683/19000 is trying to acquire lock:
ffff888049ca3cc8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_get+0x10a/0x6a0 fs/ext4/xattr.c:708

but task is already holding lock:
ffff88807df14c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1780 [inline]
ffff88807df14c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x313/0x1060 fs/ext4/migrate.c:438

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}:
       percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
       ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline]
       ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2808
       do_writepages+0x351/0x590 mm/page-writeback.c:2575
       __writeback_single_inode+0x14e/0xee0 fs/fs-writeback.c:1635
       writeback_single_inode+0x21f/0x760 fs/fs-writeback.c:1756
       write_inode_now+0x183/0x210 fs/fs-writeback.c:2808
       iput_final fs/inode.c:1807 [inline]
       iput+0x58f/0x900 fs/inode.c:1846
       ext4_xattr_block_set+0x248b/0x2fe0 fs/ext4/xattr.c:2201
       ext4_xattr_move_to_block fs/ext4/xattr.c:2666 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2741 [inline]
       ext4_expand_extra_isize_ea+0x128f/0x1e70 fs/ext4/xattr.c:2829
       __ext4_expand_extra_isize+0x306/0x400 fs/ext4/inode.c:5990
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6033 [inline]
       __ext4_mark_inode_dirty+0x458/0x6d0 fs/ext4/inode.c:6111
       ext4_evict_inode+0x7dd/0xe70 fs/ext4/inode.c:254
       evict+0x4b7/0x8a0 fs/inode.c:705
       ext4_orphan_cleanup+0xc33/0x1470 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5621 [inline]
       ext4_fill_super+0x5fb5/0x6870 fs/ext4/super.c:5744
       get_tree_bdev+0x3e5/0x520 fs/super.c:1591
       vfs_get_tree+0x8c/0x280 fs/super.c:1764
       do_new_mount+0x24a/0xa40 fs/namespace.c:3386
       do_mount fs/namespace.c:3726 [inline]
       __do_sys_mount fs/namespace.c:3935 [inline]
       __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
       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 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       ext4_xattr_get+0x10a/0x6a0 fs/ext4/xattr.c:708
       ext4_get_acl+0x84/0x6e0 fs/ext4/acl.c:165
       __get_acl+0x273/0x400 fs/posix_acl.c:160
       get_inode_acl fs/posix_acl.c:185 [inline]
       posix_acl_create+0x131/0x440 fs/posix_acl.c:648
       ext4_init_acl+0xbb/0x330 fs/ext4/acl.c:284
       __ext4_new_inode+0x2f68/0x3ad0 fs/ext4/ialloc.c:1332
       ext4_ext_migrate+0x6ca/0x1060 fs/ext4/migrate.c:456
       __ext4_ioctl fs/ext4/ioctl.c:1412 [inline]
       ext4_ioctl+0x1ede/0x3b70 fs/ext4/ioctl.c:1630
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
       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:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.0.2683/19000:
 #0: ffff88801ef5c418 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x200 fs/namespace.c:456
 #1: ffff888035842210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff888035842210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1411 [inline]
 #1: ffff888035842210 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_ioctl+0x1ed6/0x3b70 fs/ext4/ioctl.c:1630
 #2: ffff88807df14c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1780 [inline]
 #2: ffff88807df14c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x313/0x1060 fs/ext4/migrate.c:438

stack backtrace:
CPU: 0 PID: 19000 Comm: syz.0.2683 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
 ext4_xattr_get+0x10a/0x6a0 fs/ext4/xattr.c:708
 ext4_get_acl+0x84/0x6e0 fs/ext4/acl.c:165
 __get_acl+0x273/0x400 fs/posix_acl.c:160
 get_inode_acl fs/posix_acl.c:185 [inline]
 posix_acl_create+0x131/0x440 fs/posix_acl.c:648
 ext4_init_acl+0xbb/0x330 fs/ext4/acl.c:284
 __ext4_new_inode+0x2f68/0x3ad0 fs/ext4/ialloc.c:1332
 ext4_ext_migrate+0x6ca/0x1060 fs/ext4/migrate.c:456
 __ext4_ioctl fs/ext4/ioctl.c:1412 [inline]
 ext4_ioctl+0x1ede/0x3b70 fs/ext4/ioctl.c:1630
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 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: 0033:0x7efee1b9ce59
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:00007efee2a66028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007efee1e15fa0 RCX: 00007efee1b9ce59
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007efee1c32e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efee1e16038 R14: 00007efee1e15fa0 R15: 00007ffd520ff9e8
 </TASK>