syzbot

EXT4-fs error (device loop5): ext4_dirty_inode:6054: inode #15: comm syz.5.323: mark_inode_dirty error
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.323/6401 is trying to acquire lock:
ffff888062af28a8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
ffff888062af28a8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_destroy_inline_data+0x24/0xe0 fs/ext4/inline.c:1890

but task is already holding lock:
ffff88801f196bd8 (&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]
       __filemap_fdatawrite mm/filemap.c:439 [inline]
       filemap_flush+0xb3/0x100 mm/filemap.c:466
       ext4_convert_inline_data+0x17d/0x5d0 fs/ext4/inline.c:2066
       ext4_page_mkwrite+0x1d7/0x1240 fs/ext4/inode.c:6176
       do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
       do_shared_fault mm/memory.c:4328 [inline]
       do_fault mm/memory.c:4396 [inline]
       handle_pte_fault mm/memory.c:4650 [inline]
       __handle_mm_fault mm/memory.c:4785 [inline]
       handle_mm_fault+0x1d48/0x43b0 mm/memory.c:4883
       faultin_page mm/gup.c:976 [inline]
       __get_user_pages+0x93e/0x11c0 mm/gup.c:1197
       faultin_vma_page_range+0x1e0/0x260 mm/gup.c:1590
       madvise_populate mm/madvise.c:856 [inline]
       madvise_vma mm/madvise.c:1004 [inline]
       do_madvise+0x9dc/0x2b60 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 ***

4 locks held by syz.5.323/6401:
 #0: ffff88807c5b8f28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 #0: ffff88807c5b8f28 (&mm->mmap_lock){++++}-{3:3}, at: do_madvise+0x352/0x2b60 mm/madvise.c:1174
 #1: ffff88801f194558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
 #1: ffff88801f194558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline]
 #1: ffff88801f194558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x19d/0x1240 fs/ext4/inode.c:6171
 #2: ffff888062af2d70 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:842 [inline]
 #2: ffff888062af2d70 (mapping.invalidate_lock){++++}-{3:3}, at: ext4_page_mkwrite+0x1ca/0x1240 fs/ext4/inode.c:6174
 #3: ffff88801f196bd8 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x1c0/0x2d20 fs/ext4/inode.c:2689

stack backtrace:
CPU: 1 PID: 6401 Comm: syz.5.323 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]
 __filemap_fdatawrite mm/filemap.c:439 [inline]
 filemap_flush+0xb3/0x100 mm/filemap.c:466
 ext4_convert_inline_data+0x17d/0x5d0 fs/ext4/inline.c:2066
 ext4_page_mkwrite+0x1d7/0x1240 fs/ext4/inode.c:6176
 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
 do_shared_fault mm/memory.c:4328 [inline]
 do_fault mm/memory.c:4396 [inline]
 handle_pte_fault mm/memory.c:4650 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x1d48/0x43b0 mm/memory.c:4883
 faultin_page mm/gup.c:976 [inline]
 __get_user_pages+0x93e/0x11c0 mm/gup.c:1197
 faultin_vma_page_range+0x1e0/0x260 mm/gup.c:1590
 madvise_populate mm/madvise.c:856 [inline]
 madvise_vma mm/madvise.c:1004 [inline]
 do_madvise+0x9dc/0x2b60 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: 0033:0x7fdab2e5a749
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:00007fdab10c1038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fdab30b0fa0 RCX: 00007fdab2e5a749
RDX: 0000000000000017 RSI: 0000000000c00304 RDI: 0000200000000000
RBP: 00007fdab2edef91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdab30b1038 R14: 00007fdab30b0fa0 R15: 00007fffce70b388
 </TASK>