======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.3896/21308 is trying to acquire lock:
ffff88803472e610 (sb_internal){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
ffff88803472e610 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:2000 [inline]
ffff88803472e610 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:2183 [inline]
ffff88803472e610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x2d6/0xee0 fs/ext4/inode.c:215

but task is already holding lock:
ffff88803472cb98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1808 [inline]
ffff88803472cb98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010 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}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
       percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
       ext4_writepages_down_read fs/ext4/ext4.h:1796 [inline]
       ext4_writepages+0x1cc/0x350 fs/ext4/inode.c:3021
       do_writepages+0x32e/0x550 mm/page-writeback.c:2598
       __writeback_single_inode+0x143/0x12d0 fs/fs-writeback.c:1733
       writeback_single_inode+0x493/0xc70 fs/fs-writeback.c:1854
       write_inode_now+0x160/0x1d0 fs/fs-writeback.c:2920
       iput_final fs/inode.c:1948 [inline]
       iput+0xa98/0x1050 fs/inode.c:2010
       ext4_xattr_block_set+0x1fce/0x2ac0 fs/ext4/xattr.c:2199
       ext4_xattr_move_to_block fs/ext4/xattr.c:2664 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2739 [inline]
       ext4_expand_extra_isize_ea+0x12da/0x1ea0 fs/ext4/xattr.c:2827
       __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6361
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6404 [inline]
       __ext4_mark_inode_dirty+0x46c/0x700 fs/ext4/inode.c:6482
       ext4_evict_inode+0x80d/0xee0 fs/ext4/inode.c:254
       evict+0x5f4/0xae0 fs/inode.c:837
       ext4_orphan_cleanup+0xc20/0x1460 fs/ext4/orphan.c:470
       __ext4_fill_super fs/ext4/super.c:5617 [inline]
       ext4_fill_super+0x5920/0x61e0 fs/ext4/super.c:5736
       get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1692
       vfs_get_tree+0x92/0x2b0 fs/super.c:1752
       fc_mount fs/namespace.c:1198 [inline]
       do_new_mount_fc fs/namespace.c:3641 [inline]
       do_new_mount+0x302/0xa10 fs/namespace.c:3717
       do_mount fs/namespace.c:4040 [inline]
       __do_sys_mount fs/namespace.c:4228 [inline]
       __se_sys_mount+0x313/0x410 fs/namespace.c:4205
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
       percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
       __sb_start_write include/linux/fs.h:2000 [inline]
       sb_start_intwrite include/linux/fs.h:2183 [inline]
       ext4_evict_inode+0x2d6/0xee0 fs/ext4/inode.c:215
       evict+0x5f4/0xae0 fs/inode.c:837
       ext4_ext_migrate+0xd23/0x1010 fs/ext4/migrate.c:588
       __ext4_ioctl fs/ext4/ioctl.c:1694 [inline]
       ext4_ioctl+0x204b/0x48e0 fs/ext4/ioctl.c:1923
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.1.3896/21308:
 #0: ffff88803472e420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:542
 #1: ffff88805b67bd40 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:1063 [inline]
 #1: ffff88805b67bd40 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: __ext4_ioctl fs/ext4/ioctl.c:1693 [inline]
 #1: ffff88805b67bd40 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: ext4_ioctl+0x2043/0x48e0 fs/ext4/ioctl.c:1923
 #2: ffff88803472cb98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1808 [inline]
 #2: ffff88803472cb98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x2f3/0x1010 fs/ext4/migrate.c:438

stack backtrace:
CPU: 0 UID: 0 PID: 21308 Comm: syz.1.3896 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 percpu_down_read_internal+0x48/0x1c0 include/linux/percpu-rwsem.h:53
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs.h:2000 [inline]
 sb_start_intwrite include/linux/fs.h:2183 [inline]
 ext4_evict_inode+0x2d6/0xee0 fs/ext4/inode.c:215
 evict+0x5f4/0xae0 fs/inode.c:837
 ext4_ext_migrate+0xd23/0x1010 fs/ext4/migrate.c:588
 __ext4_ioctl fs/ext4/ioctl.c:1694 [inline]
 ext4_ioctl+0x204b/0x48e0 fs/ext4/ioctl.c:1923
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f69b018f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f69b1041038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f69b03e5fa0 RCX: 00007f69b018f6c9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007f69b0211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f69b03e6038 R14: 00007f69b03e5fa0 R15: 00007ffdaec639a8
 </TASK>