syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:24/4463 is trying to acquire lock:
ffff8880569080c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
ffff8880569080c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1922

but task is already holding lock:
ffff8880286dcc18 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x20f/0x2f40 fs/ext4/inode.c:2717

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+0x20f/0x2f40 fs/ext4/inode.c:2717
       do_writepages+0x3ba/0x640 mm/page-writeback.c:2491
       __writeback_single_inode+0x156/0x1160 fs/fs-writeback.c:1622
       writeback_single_inode+0x3cb/0x8e0 fs/fs-writeback.c:1743
       write_inode_now+0x17f/0x210 fs/fs-writeback.c:2786
       iput_final fs/inode.c:1821 [inline]
       iput+0x613/0x980 fs/inode.c:1860
       ext4_xattr_block_set+0x273b/0x32b0 fs/ext4/xattr.c:2146
       ext4_xattr_move_to_block fs/ext4/xattr.c:2611 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2686 [inline]
       ext4_expand_extra_isize_ea+0x120b/0x1dc0 fs/ext4/xattr.c:2774
       __ext4_expand_extra_isize+0x301/0x3e0 fs/ext4/inode.c:6003
       ext4_try_to_expand_extra_isize fs/ext4/inode.c:6046 [inline]
       __ext4_mark_inode_dirty+0x47f/0x770 fs/ext4/inode.c:6124
       ext4_evict_inode+0xa7f/0x1110 fs/ext4/inode.c:281
       evict+0x4c9/0x8d0 fs/inode.c:705
       ext4_orphan_cleanup+0xbeb/0x1420 fs/ext4/orphan.c:472
       __ext4_fill_super fs/ext4/super.c:5574 [inline]
       ext4_fill_super+0x6ee3/0x78c0 fs/ext4/super.c:5693
       get_tree_bdev+0x3f1/0x610 fs/super.c:1366
       vfs_get_tree+0x88/0x270 fs/super.c:1573
       do_new_mount+0x24a/0xa40 fs/namespace.c:3078
       do_mount fs/namespace.c:3421 [inline]
       __do_sys_mount fs/namespace.c:3629 [inline]
       __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/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:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       down_write+0x36/0x60 kernel/locking/rwsem.c:1573
       ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
       ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1922
       ext4_writepages+0x670/0x2f40 fs/ext4/inode.c:2763
       do_writepages+0x3ba/0x640 mm/page-writeback.c:2491
       __writeback_single_inode+0x156/0x1160 fs/fs-writeback.c:1622
       writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
       wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
       wb_do_writeback fs/fs-writeback.c:2230 [inline]
       wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
       process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
       worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
       kthread+0x29d/0x330 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

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 kworker/u4:24/4463:
 #0: ffff8880176d4938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000495fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffff8880286dcc18 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x20f/0x2f40 fs/ext4/inode.c:2717

stack backtrace:
CPU: 0 PID: 4463 Comm: kworker/u4:24 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: writeback wb_workfn (flush-7:4)
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 down_write+0x36/0x60 kernel/locking/rwsem.c:1573
 ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
 ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1922
 ext4_writepages+0x670/0x2f40 fs/ext4/inode.c:2763
 do_writepages+0x3ba/0x640 mm/page-writeback.c:2491
 __writeback_single_inode+0x156/0x1160 fs/fs-writeback.c:1622
 writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
 wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
 wb_do_writeback fs/fs-writeback.c:2230 [inline]
 wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
EXT4-fs error (device loop4): ext4_validate_block_bitmap:429: comm kworker/u4:24: bg 0: block 5: invalid block bitmap
EXT4-fs (loop4): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 28
EXT4-fs (loop4): This should not happen!! Data will be lost

EXT4-fs (loop4): Total free blocks count 0
EXT4-fs (loop4): Free/Dirty block details
EXT4-fs (loop4): free_blocks=0
EXT4-fs (loop4): dirty_blocks=5
EXT4-fs (loop4): Block reservation details
EXT4-fs (loop4): i_reserved_data_blocks=5
EXT4-fs (loop4): Delayed block allocation failed for inode 15 at logical offset 36 with max blocks 4 with error 28