======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.1268/10240 is trying to acquire lock:
ffff888053c34610 (sb_internal){.+.+}-{0:0}, at: percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
ffff888053c34610 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs/super.h:19 [inline]
ffff888053c34610 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs/super.h:177 [inline]
ffff888053c34610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x274/0xe60 fs/ext4/inode.c:216

but task is already holding lock:
ffff888026186b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1829 [inline]
ffff888026186b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x308/0x1140 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+0x48/0x1c0 include/linux/percpu-rwsem.h:53
       percpu_down_read include/linux/percpu-rwsem.h:77 [inline]
       ext4_writepages_down_read fs/ext4/ext4.h:1817 [inline]
       ext4_writepages+0x205/0x3b0 fs/ext4/inode.c:3018
       do_writepages+0x32e/0x550 mm/page-writeback.c:2554
       __writeback_single_inode+0x133/0x1060 fs/fs-writeback.c:1750
       writeback_single_inode+0x4ac/0xdc0 fs/fs-writeback.c:1869
       write_inode_now+0x1c2/0x290 fs/fs-writeback.c:2954
       iput_final fs/inode.c:1956 [inline]
       iput+0x8c1/0xe80 fs/inode.c:2015
       ext4_xattr_block_set+0x1fd4/0x2ad0 fs/ext4/xattr.c:2204
       ext4_xattr_move_to_block fs/ext4/xattr.c:2669 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2744 [inline]
       ext4_expand_extra_isize_ea+0x12cf/0x1ea0 fs/ext4/xattr.c:2832
       __ext4_expand_extra_isize+0x30d/0x400 fs/ext4/inode.c:6324
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6367 [inline]
       __ext4_mark_inode_dirty+0x45c/0x6e0 fs/ext4/inode.c:6445
       ext4_evict_inode+0x7a1/0xe60 fs/ext4/inode.c:255
       evict+0x61e/0xb10 fs/inode.c:846
       ext4_orphan_cleanup+0xc38/0x1470 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5673 [inline]
       ext4_fill_super+0x59ff/0x6320 fs/ext4/super.c:5796
       get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
       vfs_get_tree+0x92/0x2a0 fs/super.c:1754
       fc_mount fs/namespace.c:1193 [inline]
       do_new_mount_fc fs/namespace.c:3760 [inline]
       do_new_mount+0x341/0xd30 fs/namespace.c:3836
       do_mount fs/namespace.c:4159 [inline]
       __do_sys_mount fs/namespace.c:4348 [inline]
       __se_sys_mount+0x31d/0x420 fs/namespace.c:4325
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xe2/0xf80 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 kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x330 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/super.h:19 [inline]
       sb_start_intwrite include/linux/fs/super.h:177 [inline]
       ext4_evict_inode+0x274/0xe60 fs/ext4/inode.c:216
       evict+0x61e/0xb10 fs/inode.c:846
       ext4_ext_migrate+0xe2a/0x1140 fs/ext4/migrate.c:594
       __ext4_ioctl fs/ext4/ioctl.c:1693 [inline]
       ext4_ioctl+0x234c/0x4b30 fs/ext4/ioctl.c:1922
       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+0xe2/0xf80 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.5.1268/10240:
 #0: ffff888053c34420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:537
 #1: ffff8880125f3400 (&sb->s_type->i_mutex_key#12){++++}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff8880125f3400 (&sb->s_type->i_mutex_key#12){++++}-{4:4}, at: __ext4_ioctl fs/ext4/ioctl.c:1692 [inline]
 #1: ffff8880125f3400 (&sb->s_type->i_mutex_key#12){++++}-{4:4}, at: ext4_ioctl+0x2344/0x4b30 fs/ext4/ioctl.c:1922
 #2: ffff888026186b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_write fs/ext4/ext4.h:1829 [inline]
 #2: ffff888026186b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x308/0x1140 fs/ext4/migrate.c:438

stack backtrace:
CPU: 0 UID: 0 PID: 10240 Comm: syz.5.1268 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 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 kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x330 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/super.h:19 [inline]
 sb_start_intwrite include/linux/fs/super.h:177 [inline]
 ext4_evict_inode+0x274/0xe60 fs/ext4/inode.c:216
 evict+0x61e/0xb10 fs/inode.c:846
 ext4_ext_migrate+0xe2a/0x1140 fs/ext4/migrate.c:594
 __ext4_ioctl fs/ext4/ioctl.c:1693 [inline]
 ext4_ioctl+0x234c/0x4b30 fs/ext4/ioctl.c:1922
 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+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f45fd39aeb9
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:00007f45fe244028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f45fd615fa0 RCX: 00007f45fd39aeb9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000004
RBP: 00007f45fd408c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45fd616038 R14: 00007f45fd615fa0 R15: 00007ffd615e6218
 </TASK>