======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.6.2466/13739 is trying to acquire lock:
ffff8880339427f0 (sb_internal){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
ffff8880339427f0 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs/super.h:19 [inline]
ffff8880339427f0 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs/super.h:177 [inline]
ffff8880339427f0 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x426/0x10c0 fs/ext4/inode.c:228

but task is already holding lock:
ffff88807d2f4cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1888 [inline]
ffff88807d2f4cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x317/0x10e0 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_internal+0x48/0x1d0 include/linux/percpu-rwsem.h:53
       percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
       ext4_writepages_down_read fs/ext4/ext4.h:1876 [inline]
       ext4_writepages+0x205/0x3b0 fs/ext4/inode.c:3042
       do_writepages+0x338/0x560 mm/page-writeback.c:2571
       __writeback_single_inode+0x12e/0xf90 fs/fs-writeback.c:1787
       writeback_single_inode+0x4dd/0xe10 fs/fs-writeback.c:1906
       write_inode_now+0x1c2/0x290 fs/fs-writeback.c:3060
       iput_final fs/inode.c:2009 [inline]
       iput+0x98b/0xf00 fs/inode.c:2068
       ext4_xattr_block_set+0x1b0c/0x2a80 fs/ext4/xattr.c:2206
       ext4_xattr_move_to_block fs/ext4/xattr.c:2671 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2746 [inline]
       ext4_expand_extra_isize_ea+0x1342/0x1e70 fs/ext4/xattr.c:2834
       __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6486
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6529 [inline]
       __ext4_mark_inode_dirty+0x455/0x700 fs/ext4/inode.c:6607
       ext4_evict_inode+0x976/0x10c0 fs/ext4/inode.c:267
       evict+0x624/0xb50 fs/inode.c:825
       ext4_orphan_cleanup+0xc7a/0x14c0 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5705 [inline]
       ext4_fill_super+0x5cc0/0x65d0 fs/ext4/super.c:5828
       get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1634
       vfs_get_tree+0x92/0x2a0 fs/super.c:1694
       fc_mount fs/namespace.c:1198 [inline]
       do_new_mount_fc fs/namespace.c:3765 [inline]
       do_new_mount+0x319/0xdc0 fs/namespace.c:3841
       do_mount fs/namespace.c:4174 [inline]
       __do_sys_mount fs/namespace.c:4390 [inline]
       __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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:3167 [inline]
       check_prevs_add kernel/locking/lockdep.c:3286 [inline]
       validate_chain kernel/locking/lockdep.c:3910 [inline]
       __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5239
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
       percpu_down_read_internal+0x48/0x1d0 include/linux/percpu-rwsem.h:53
       percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
       __sb_start_write include/linux/fs/super.h:19 [inline]
       sb_start_intwrite include/linux/fs/super.h:177 [inline]
       ext4_evict_inode+0x426/0x10c0 fs/ext4/inode.c:228
       evict+0x624/0xb50 fs/inode.c:825
       ext4_ext_migrate+0xddf/0x10e0 fs/ext4/migrate.c:594
       __ext4_ioctl fs/ext4/ioctl.c:1702 [inline]
       ext4_ioctl+0x234f/0x4b80 fs/ext4/ioctl.c:1931
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 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.6.2466/13739:
 #0: ffff888033942500 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:538
 #1: ffff88803348cb38 (&type->i_mutex_dir_key#3){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff88803348cb38 (&type->i_mutex_dir_key#3){++++}-{4:4}, at: __ext4_ioctl fs/ext4/ioctl.c:1701 [inline]
 #1: ffff88803348cb38 (&type->i_mutex_dir_key#3){++++}-{4:4}, at: ext4_ioctl+0x2347/0x4b80 fs/ext4/ioctl.c:1931
 #2: ffff88807d2f4cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1888 [inline]
 #2: ffff88807d2f4cd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x317/0x10e0 fs/ext4/migrate.c:438

stack backtrace:
CPU: 0 UID: 0 PID: 13739 Comm: syz.6.2466 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2045
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3167 [inline]
 check_prevs_add kernel/locking/lockdep.c:3286 [inline]
 validate_chain kernel/locking/lockdep.c:3910 [inline]
 __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5239
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
 percpu_down_read_internal+0x48/0x1d0 include/linux/percpu-rwsem.h:53
 percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
 __sb_start_write include/linux/fs/super.h:19 [inline]
 sb_start_intwrite include/linux/fs/super.h:177 [inline]
 ext4_evict_inode+0x426/0x10c0 fs/ext4/inode.c:228
 evict+0x624/0xb50 fs/inode.c:825
 ext4_ext_migrate+0xddf/0x10e0 fs/ext4/migrate.c:594
 __ext4_ioctl fs/ext4/ioctl.c:1702 [inline]
 ext4_ioctl+0x234f/0x4b80 fs/ext4/ioctl.c:1931
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa9c51dce59
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:00007fa9c340d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa9c5456090 RCX: 00007fa9c51dce59
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000007
RBP: 00007fa9c5272e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa9c5456128 R14: 00007fa9c5456090 R15: 00007ffeb95bd568
 </TASK>