syzbot

loop6: detected capacity change from 0 to 2048
EXT4-fs (loop6): mounted filesystem without journal. Opts: nogrpid,noload,,errors=continue. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.1976/12909 is trying to acquire lock:
ffff88805f9a0ac0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
ffff88805f9a0ac0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1900

but task is already holding lock:
ffff88807df56c58 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x20f/0x2df0 fs/ext4/inode.c:2691

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+0x46/0x1b0 include/linux/percpu-rwsem.h:51
       ext4_writepages+0x20f/0x2df0 fs/ext4/inode.c:2691
       do_writepages+0x476/0x6e0 mm/page-writeback.c:2386
       __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
       writeback_single_inode+0x3cb/0x8e0 fs/fs-writeback.c:1770
       write_inode_now+0x23b/0x2c0 fs/fs-writeback.c:2817
       iput_final fs/inode.c:1756 [inline]
       iput+0x5ab/0x8a0 fs/inode.c:1795
       ext4_xattr_set_entry+0x34f4/0x3ea0 fs/ext4/xattr.c:1827
       ext4_xattr_block_set+0x4fd/0x2d20 fs/ext4/xattr.c:1926
       ext4_xattr_move_to_block fs/ext4/xattr.c:2620 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2695 [inline]
       ext4_expand_extra_isize_ea+0xf3f/0x19b0 fs/ext4/xattr.c:2783
       __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:5924
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5967 [inline]
       __ext4_mark_inode_dirty+0x469/0x700 fs/ext4/inode.c:6045
       ext4_evict_inode+0xa8d/0x1090 fs/ext4/inode.c:284
       evict+0x4c9/0x8d0 fs/inode.c:647
       ext4_orphan_cleanup+0xad2/0x1320 fs/ext4/orphan.c:472
       ext4_fill_super+0x8d6e/0x94f0 fs/ext4/super.c:5006
       mount_bdev+0x287/0x3c0 fs/super.c:1400
       legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
       vfs_get_tree+0x88/0x270 fs/super.c:1530
       do_new_mount+0x24a/0xa40 fs/namespace.c:3034
       do_mount fs/namespace.c:3377 [inline]
       __do_sys_mount fs/namespace.c:3585 [inline]
       __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&ei->xattr_sem){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
       ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1900
       ext4_writepages+0x670/0x2df0 fs/ext4/inode.c:2737
       do_writepages+0x476/0x6e0 mm/page-writeback.c:2386
       filemap_fdatawrite_wbc+0x1eb/0x240 mm/filemap.c:400
       __filemap_fdatawrite_range mm/filemap.c:433 [inline]
       __filemap_fdatawrite mm/filemap.c:439 [inline]
       filemap_flush+0xd4/0x130 mm/filemap.c:466
       ext4_convert_inline_data+0x18b/0x5f0 fs/ext4/inline.c:2076
       ext4_fallocate+0xf4/0x1ed0 fs/ext4/extents.c:4775
       vfs_fallocate+0x587/0x6f0 fs/open.c:308
       madvise_remove mm/madvise.c:928 [inline]
       madvise_vma mm/madvise.c:992 [inline]
       do_madvise+0x1035/0x2c90 mm/madvise.c:1207
       __do_sys_madvise mm/madvise.c:1233 [inline]
       __se_sys_madvise mm/madvise.c:1231 [inline]
       __x64_sys_madvise+0xa2/0xb0 mm/madvise.c:1231
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.6.1976/12909:
 #0: ffff8880201ae460 (sb_writers#5){++++}-{0:0}, at: file_start_write include/linux/fs.h:3043 [inline]
 #0: ffff8880201ae460 (sb_writers#5){++++}-{0:0}, at: vfs_fallocate+0x4f4/0x6f0 fs/open.c:307
 #1: ffff88805f9a0de8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff88805f9a0de8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_fallocate+0xec/0x1ed0 fs/ext4/extents.c:4774
 #2: ffff88807df56c58 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x20f/0x2df0 fs/ext4/inode.c:2691

stack backtrace:
CPU: 1 PID: 12909 Comm: syz.6.1976 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 down_write+0x38/0x60 kernel/locking/rwsem.c:1551
 ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
 ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1900
 ext4_writepages+0x670/0x2df0 fs/ext4/inode.c:2737
 do_writepages+0x476/0x6e0 mm/page-writeback.c:2386
 filemap_fdatawrite_wbc+0x1eb/0x240 mm/filemap.c:400
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 __filemap_fdatawrite mm/filemap.c:439 [inline]
 filemap_flush+0xd4/0x130 mm/filemap.c:466
 ext4_convert_inline_data+0x18b/0x5f0 fs/ext4/inline.c:2076
 ext4_fallocate+0xf4/0x1ed0 fs/ext4/extents.c:4775
 vfs_fallocate+0x587/0x6f0 fs/open.c:308
 madvise_remove mm/madvise.c:928 [inline]
 madvise_vma mm/madvise.c:992 [inline]
 do_madvise+0x1035/0x2c90 mm/madvise.c:1207
 __do_sys_madvise mm/madvise.c:1233 [inline]
 __se_sys_madvise mm/madvise.c:1231 [inline]
 __x64_sys_madvise+0xa2/0xb0 mm/madvise.c:1231
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7feec92dbe59
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:00007feec7535028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007feec9554fa0 RCX: 00007feec92dbe59
RDX: 0000000000000009 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007feec9371d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feec9555038 R14: 00007feec9554fa0 R15: 00007ffd8a74f068
 </TASK>
EXT4-fs error (device loop6): ext4_mb_generate_buddy:1176: group 0, block bitmap and bg descriptor inconsistent: 25 vs 281 free clusters
EXT4-fs (loop6): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 28
EXT4-fs (loop6): This should not happen!! Data will be lost

EXT4-fs (loop6): Total free blocks count 0
EXT4-fs (loop6): Free/Dirty block details
EXT4-fs (loop6): free_blocks=4096
EXT4-fs (loop6): dirty_blocks=16
EXT4-fs (loop6): Block reservation details
EXT4-fs (loop6): i_reserved_data_blocks=1