syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.247/5877 is trying to acquire lock:
ffff0000f516db10 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_get+0xec/0x544 fs/ext4/xattr.c:660

but task is already holding lock:
ffff0000df42ab98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x204/0xbfc fs/ext4/migrate.c:437

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+0x70/0x2a8 include/linux/percpu-rwsem.h:51
       ext4_writepages+0x188/0x284c fs/ext4/inode.c:2715
       do_writepages+0x2c0/0x4fc mm/page-writeback.c:2491
       __writeback_single_inode+0x164/0x157c fs/fs-writeback.c:1622
       writeback_single_inode+0x1c0/0x720 fs/fs-writeback.c:1743
       write_inode_now+0x144/0x1b0 fs/fs-writeback.c:2780
       iput_final fs/inode.c:1821 [inline]
       iput+0x5cc/0x7f4 fs/inode.c:1860
       ext4_xattr_block_set+0x17a4/0x2810 fs/ext4/xattr.c:2158
       ext4_xattr_move_to_block fs/ext4/xattr.c:2626 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2701 [inline]
       ext4_expand_extra_isize_ea+0xcb8/0x15cc fs/ext4/xattr.c:2793
       __ext4_expand_extra_isize+0x298/0x358 fs/ext4/inode.c:5980
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6023 [inline]
       __ext4_mark_inode_dirty+0x3e4/0x790 fs/ext4/inode.c:6101
       ext4_evict_inode+0xb58/0x1270 fs/ext4/inode.c:279
       evict+0x3c8/0x810 fs/inode.c:705
       iput_final fs/inode.c:1834 [inline]
       iput+0x764/0x7f4 fs/inode.c:1860
       ext4_process_orphan+0x240/0x2b4 fs/ext4/orphan.c:356
       ext4_orphan_cleanup+0x908/0x104c fs/ext4/orphan.c:470
       __ext4_fill_super fs/ext4/super.c:5530 [inline]
       ext4_fill_super+0x6440/0x68a8 fs/ext4/super.c:5661
       get_tree_bdev+0x358/0x544 fs/super.c:1366
       ext4_get_tree+0x28/0x38 fs/ext4/super.c:5691
       vfs_get_tree+0x90/0x274 fs/super.c:1573
       do_new_mount+0x228/0x810 fs/namespace.c:3078
       path_mount+0x5b4/0xe78 fs/namespace.c:3408
       do_mount fs/namespace.c:3421 [inline]
       __do_sys_mount fs/namespace.c:3629 [inline]
       __se_sys_mount fs/namespace.c:3606 [inline]
       __arm64_sys_mount+0x49c/0x584 fs/namespace.c:3606
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 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 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
       lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
       down_read+0x64/0x304 kernel/locking/rwsem.c:1520
       ext4_xattr_get+0xec/0x544 fs/ext4/xattr.c:660
       ext4_get_acl+0x94/0x5f0 fs/ext4/acl.c:165
       get_acl+0x160/0x33c fs/posix_acl.c:153
       posix_acl_create+0x104/0x3d0 fs/posix_acl.c:632
       ext4_init_acl+0xac/0x340 fs/ext4/acl.c:283
       __ext4_new_inode+0x27b8/0x3340 fs/ext4/ialloc.c:1328
       ext4_ext_migrate+0x498/0xbfc fs/ext4/migrate.c:455
       ext4_ioctl_setflags fs/ext4/ioctl.c:695 [inline]
       ext4_fileattr_set+0xc30/0x12c0 fs/ext4/ioctl.c:1008
       vfs_fileattr_set+0x674/0x8fc fs/ioctl.c:696
       do_vfs_ioctl+0x1a58/0x206c fs/ioctl.c:-1
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 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:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.4.247/5877:
 #0: ffff0000df428460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:446
 #1: ffff0000f516de48 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff0000f516de48 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: vfs_fileattr_set+0x108/0x8fc fs/ioctl.c:681
 #2: ffff0000df42ab98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x204/0xbfc fs/ext4/migrate.c:437

stack backtrace:
CPU: 1 PID: 5877 Comm: syz.4.247 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 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+0xf8/0x160 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+0x240/0x2d4 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
 lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
 down_read+0x64/0x304 kernel/locking/rwsem.c:1520
 ext4_xattr_get+0xec/0x544 fs/ext4/xattr.c:660
 ext4_get_acl+0x94/0x5f0 fs/ext4/acl.c:165
 get_acl+0x160/0x33c fs/posix_acl.c:153
 posix_acl_create+0x104/0x3d0 fs/posix_acl.c:632
 ext4_init_acl+0xac/0x340 fs/ext4/acl.c:283
 __ext4_new_inode+0x27b8/0x3340 fs/ext4/ialloc.c:1328
 ext4_ext_migrate+0x498/0xbfc fs/ext4/migrate.c:455
 ext4_ioctl_setflags fs/ext4/ioctl.c:695 [inline]
 ext4_fileattr_set+0xc30/0x12c0 fs/ext4/ioctl.c:1008
 vfs_fileattr_set+0x674/0x8fc fs/ioctl.c:696
 do_vfs_ioctl+0x1a58/0x206c fs/ioctl.c:-1
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 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