syzbot

EXT4-fs (loop5): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
EXT4-fs error (device loop5) in ext4_reserve_inode_write:5920: Out of memory
EXT4-fs error (device loop5): ext4_setattr:5602: inode #15: comm syz.5.956: mark_inode_dirty error
EXT4-fs error (device loop5) in ext4_setattr:5663: Out of memory
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.956/9619 is trying to acquire lock:
ffff8880512050c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:158 [inline]
ffff8880512050c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x28/0xe0 fs/ext4/inline.c:1894

but task is already holding lock:
ffff88802803cbd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1767 [inline]
ffff88802803cbd8 (&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:2808
       iput_final fs/inode.c:1807 [inline]
       iput+0x5ae/0x920 fs/inode.c:1846
       ext4_xattr_block_set+0x273f/0x32b0 fs/ext4/xattr.c:2199
       ext4_xattr_move_to_block fs/ext4/xattr.c:2664 [inline]
       ext4_xattr_make_inode_space fs/ext4/xattr.c:2739 [inline]
       ext4_expand_extra_isize_ea+0x12c5/0x1e80 fs/ext4/xattr.c:2827
       __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]
       __filemap_fdatawrite mm/filemap.c:429 [inline]
       filemap_flush+0xe4/0x150 mm/filemap.c:456
       ext4_release_file+0x82/0x310 fs/ext4/file.c:169
       __fput+0x234/0x970 fs/file_table.c:384
       task_work_run+0x1d4/0x260 kernel/task_work.c:245
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
       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 ***

1 lock held by syz.5.956/9619:
 #0: ffff88802803cbd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1767 [inline]
 #0: ffff88802803cbd8 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2806

stack backtrace:
CPU: 1 PID: 9619 Comm: syz.5.956 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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]
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0xe4/0x150 mm/filemap.c:456
 ext4_release_file+0x82/0x310 fs/ext4/file.c:169
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6a60d9bf79
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:00007f6a61d3c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: fffffffffffffff4 RBX: 00007f6a61015fa0 RCX: 00007f6a60d9bf79
RDX: 0000000000000000 RSI: 0000000000000186 RDI: 0000200000000100
RBP: 00007f6a60e327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6a61016038 R14: 00007f6a61015fa0 R15: 00007ffcb90c1248
 </TASK>
syz.5.956: attempt to access beyond end of device
loop5: rw=1, sector=3606377190, nr_sectors = 2 limit=1024
EXT4-fs warning (device loop5): ext4_end_bio:357: I/O error 10 writing to inode 15 starting block 1803188595)
Buffer I/O error on device loop5, logical block 1803188595
EXT4-fs error (device loop5) in ext4_reserve_inode_write:5920: Out of memory
EXT4-fs error (device loop5): mpage_map_and_submit_extent:2315: inode #15: comm syz.5.956: mark_inode_dirty error
EXT4-fs error (device loop5): mpage_map_and_submit_extent:2319: comm syz.5.956: Failed to mark inode 15 dirty
syz.5.956: attempt to access beyond end of device
loop5: rw=1, sector=3403208898, nr_sectors = 2 limit=1024
EXT4-fs warning (device loop5): ext4_end_bio:357: I/O error 10 writing to inode 15 starting block 1701604449)
Buffer I/O error on device loop5, logical block 1701604449