syzbot

EXT4-fs (loop5): mounted filesystem without journal. Opts: discard,bh,mb_optimize_scan=0x0000000000000001,,errors=continue. Quota mode: none.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.220/5540 is trying to acquire lock:
ffff888073fd0ac0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff888073fd0ac0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1890

but task is already holding lock:
ffff888074d74bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689

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+0x1c0/0x2d20 fs/ext4/inode.c:2689
       do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
       __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657
       writeback_single_inode+0x221/0x8b0 fs/fs-writeback.c:1770
       write_inode_now+0x217/0x280 fs/fs-writeback.c:2811
       iput_final fs/inode.c:1756 [inline]
       iput+0x5ab/0x8a0 fs/inode.c:1795
       ext4_xattr_set_entry+0x10ff/0x3d30 fs/ext4/xattr.c:1837
       ext4_xattr_block_set+0x4f7/0x2d30 fs/ext4/xattr.c:1936
       ext4_xattr_move_to_block fs/ext4/xattr.c:2633 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2708 [inline]
       ext4_expand_extra_isize_ea+0xf4b/0x19a0 fs/ext4/xattr.c:2800
       __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:5901
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:5944 [inline]
       __ext4_mark_inode_dirty+0x469/0x700 fs/ext4/inode.c:6022
       ext4_evict_inode+0xa81/0x1080 fs/ext4/inode.c:282
       evict+0x485/0x870 fs/inode.c:647
       ext4_orphan_cleanup+0xaa9/0x12e0 fs/ext4/orphan.c:470
       ext4_fill_super+0x92f0/0x9a60 fs/ext4/super.c:4975
       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+0x2d6/0x3c0 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       down_write+0x38/0x60 kernel/locking/rwsem.c:1551
       ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
       ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1890
       ext4_writepages+0x5df/0x2d20 fs/ext4/inode.c:2735
       do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
       filemap_fdatawrite_wbc+0x1eb/0x240 mm/filemap.c:400
       __filemap_fdatawrite_range mm/filemap.c:433 [inline]
       file_write_and_wait_range+0x129/0x1e0 mm/filemap.c:810
       ext4_sync_file+0x1ff/0xae0 fs/ext4/fsync.c:151
       generic_write_sync include/linux/fs.h:2990 [inline]
       ext4_buffered_write_iter+0x338/0x3b0 fs/ext4/file.c:275
       ext4_file_write_iter+0x773/0x17b0 fs/ext4/file.c:-1
       do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
       do_iter_write+0x205/0x7b0 fs/read_write.c:855
       vfs_writev fs/read_write.c:928 [inline]
       do_pwritev+0x204/0x340 fs/read_write.c:1025
       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 ***

2 locks held by syz.5.220/5540:
 #0: ffff888074d76460 (sb_writers#5){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:927 [inline]
 #0: ffff888074d76460 (sb_writers#5){.+.+}-{0:0}, at: do_pwritev+0x1f2/0x340 fs/read_write.c:1025
 #1: ffff888074d74bd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689

stack backtrace:
CPU: 0 PID: 5540 Comm: syz.5.220 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 down_write+0x38/0x60 kernel/locking/rwsem.c:1551
 ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1890
 ext4_writepages+0x5df/0x2d20 fs/ext4/inode.c:2735
 do_writepages+0x48d/0x6d0 mm/page-writeback.c:2386
 filemap_fdatawrite_wbc+0x1eb/0x240 mm/filemap.c:400
 __filemap_fdatawrite_range mm/filemap.c:433 [inline]
 file_write_and_wait_range+0x129/0x1e0 mm/filemap.c:810
 ext4_sync_file+0x1ff/0xae0 fs/ext4/fsync.c:151
 generic_write_sync include/linux/fs.h:2990 [inline]
 ext4_buffered_write_iter+0x338/0x3b0 fs/ext4/file.c:275
 ext4_file_write_iter+0x773/0x17b0 fs/ext4/file.c:-1
 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x204/0x340 fs/read_write.c:1025
 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: 0033:0x7ff068a72749
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:00007ff066cd9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007ff068cc8fa0 RCX: 00007ff068a72749
RDX: 0000000000000001 RSI: 0000200000000280 RDI: 0000000000000007
RBP: 00007ff068af6f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000005412 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff068cc9038 R14: 00007ff068cc8fa0 R15: 00007ffea191e358
 </TASK>
EXT4-fs error (device loop5): ext4_mb_generate_buddy:1147: group 0, block bitmap and bg descriptor inconsistent: 25 vs 150994969 free clusters
EXT4-fs (loop5): Delayed block allocation failed for inode 15 at logical offset 10 with max blocks 1 with error 28
EXT4-fs (loop5): This should not happen!! Data will be lost

EXT4-fs (loop5): Total free blocks count 0
EXT4-fs (loop5): Free/Dirty block details
EXT4-fs (loop5): free_blocks=2415919104
EXT4-fs (loop5): dirty_blocks=16
EXT4-fs (loop5): Block reservation details
EXT4-fs (loop5): i_reserved_data_blocks=1