syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.471/6960 is trying to acquire lock:
ffff888076b080c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
ffff888076b080c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x28/0xe0 fs/ext4/inline.c:1894

but task is already holding lock:
ffff88801db48bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1767 [inline]
ffff88801db48bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2806

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:1767 [inline]
       ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2806
       do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
       __writeback_single_inode+0x153/0xec0 fs/fs-writeback.c:1635
       writeback_single_inode+0x21f/0x760 fs/fs-writeback.c:1756
       write_inode_now+0x183/0x210 fs/fs-writeback.c:2802
       iput_final fs/inode.c:1807 [inline]
       iput+0x5ae/0x920 fs/inode.c:1846
       ext4_xattr_block_set+0x273f/0x32b0 fs/ext4/xattr.c:2198
       ext4_xattr_move_to_block fs/ext4/xattr.c:2663 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2738 [inline]
       ext4_expand_extra_isize_ea+0x12c5/0x1e80 fs/ext4/xattr.c:2826
       __ext4_expand_extra_isize+0x306/0x400 fs/ext4/inode.c:5971
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6014 [inline]
       __ext4_mark_inode_dirty+0x45d/0x6e0 fs/ext4/inode.c:6092
       ext4_evict_inode+0x7f3/0xea0 fs/ext4/inode.c:252
       evict+0x4ca/0x8d0 fs/inode.c:705
       ext4_orphan_cleanup+0xbec/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5617 [inline]
       ext4_fill_super+0x5ed3/0x6790 fs/ext4/super.c:5740
       get_tree_bdev+0x3f3/0x520 fs/super.c:1591
       vfs_get_tree+0x8c/0x280 fs/super.c:1764
       do_new_mount+0x24b/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+0x55/0xa0 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+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       down_write+0x97/0x200 kernel/locking/rwsem.c:1573
       ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
       ext4_destroy_inline_data+0x28/0xe0 fs/ext4/inline.c:1894
       ext4_do_writepages+0x4f0/0x3990 fs/ext4/inode.c:2604
       ext4_writepages+0x1dd/0x350 fs/ext4/inode.c:2807
       do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
       filemap_fdatawrite_wbc+0x122/0x180 mm/filemap.c:390
       __filemap_fdatawrite_range mm/filemap.c:423 [inline]
       file_write_and_wait_range+0x197/0x280 mm/filemap.c:781
       generic_buffers_fsync_noflush+0x6f/0x160 fs/buffer.c:609
       ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
       ext4_sync_file+0x454/0xc00 fs/ext4/fsync.c:151
       generic_write_sync include/linux/fs.h:2651 [inline]
       ext4_buffered_write_iter+0x2c0/0x350 fs/ext4/file.c:305
       ext4_file_write_iter+0x1d9/0x1880 fs/ext4/file.c:-1
       do_iter_readv_writev fs/read_write.c:-1 [inline]
       do_iter_write+0x738/0xc30 fs/read_write.c:860
       iter_file_splice_write+0x6a3/0xcb0 fs/splice.c:736
       do_splice_from fs/splice.c:933 [inline]
       direct_splice_actor+0xe8/0x130 fs/splice.c:1142
       splice_direct_to_actor+0x304/0x8c0 fs/splice.c:1088
       do_splice_direct+0x1d5/0x2f0 fs/splice.c:1194
       generic_copy_file_range fs/read_write.c:1392 [inline]
       vfs_copy_file_range+0xa98/0x15c0 fs/read_write.c:1538
       __do_sys_copy_file_range fs/read_write.c:1595 [inline]
       __se_sys_copy_file_range+0x324/0x470 fs/read_write.c:1558
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 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
       ----                    ----
  rlock(&sbi->s_writepages_rwsem);
                               lock(&ei->xattr_sem);
                               lock(&sbi->s_writepages_rwsem);
  lock(&ei->xattr_sem);

 *** DEADLOCK ***

2 locks held by syz.1.471/6960:
 #0: ffff88801db4a418 (sb_writers#4){.+.+}-{0:0}, at: vfs_copy_file_range+0x8ee/0x15c0 fs/read_write.c:1501
 #1: ffff88801db48bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1767 [inline]
 #1: ffff88801db48bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2806

stack backtrace:
CPU: 0 PID: 6960 Comm: syz.1.471 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 down_write+0x97/0x200 kernel/locking/rwsem.c:1573
 ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
 ext4_destroy_inline_data+0x28/0xe0 fs/ext4/inline.c:1894
 ext4_do_writepages+0x4f0/0x3990 fs/ext4/inode.c:2604
 ext4_writepages+0x1dd/0x350 fs/ext4/inode.c:2807
 do_writepages+0x3b3/0x630 mm/page-writeback.c:2575
 filemap_fdatawrite_wbc+0x122/0x180 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 file_write_and_wait_range+0x197/0x280 mm/filemap.c:781
 generic_buffers_fsync_noflush+0x6f/0x160 fs/buffer.c:609
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x454/0xc00 fs/ext4/fsync.c:151
 generic_write_sync include/linux/fs.h:2651 [inline]
 ext4_buffered_write_iter+0x2c0/0x350 fs/ext4/file.c:305
 ext4_file_write_iter+0x1d9/0x1880 fs/ext4/file.c:-1
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x738/0xc30 fs/read_write.c:860
 iter_file_splice_write+0x6a3/0xcb0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0xe8/0x130 fs/splice.c:1142
 splice_direct_to_actor+0x304/0x8c0 fs/splice.c:1088
 do_splice_direct+0x1d5/0x2f0 fs/splice.c:1194
 generic_copy_file_range fs/read_write.c:1392 [inline]
 vfs_copy_file_range+0xa98/0x15c0 fs/read_write.c:1538
 __do_sys_copy_file_range fs/read_write.c:1595 [inline]
 __se_sys_copy_file_range+0x324/0x470 fs/read_write.c:1558
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb0c439acb9
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:00007fb0c51a5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000146
RAX: ffffffffffffffda RBX: 00007fb0c4616090 RCX: 00007fb0c439acb9
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fb0c4408bf7 R08: 0000000000000863 R09: 0200000000000000
R10: 00002000000000c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb0c4616128 R14: 00007fb0c4616090 R15: 00007ffea3669698
 </TASK>
EXT4-fs error (device loop1): ext4_validate_block_bitmap:430: comm syz.1.471: bg 0: block 5: invalid block bitmap
EXT4-fs (loop1): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 28
EXT4-fs (loop1): This should not happen!! Data will be lost

EXT4-fs (loop1): Total free blocks count 0
EXT4-fs (loop1): Free/Dirty block details
EXT4-fs (loop1): free_blocks=0
EXT4-fs (loop1): dirty_blocks=67
EXT4-fs (loop1): Block reservation details
EXT4-fs (loop1): i_reserved_data_blocks=67