bcachefs (loop0): dirent points to missing inode:
  u64s 7 type dirent 4096:8634847617288062799:U32_MAX len 0 ver 0: file3 -> 536870913 type reg, fixing
bcachefs (loop0): hash table key at wrong offset: should be at 3301975688049795851
  u64s 8 type dirent 4096:9097378837824744618:U32_MAX len 0 ver 0: file.cold -> 536870914 type reg, fixing
bcachefs (loop0): hash table key at wrong offset: should be at 395585155041010525
  u64s 7 type dirent 4098:5675548428000973578:U32_MAX len 0 ver 0: file1 -> 4100 type lnk, fixing
bcachefs (loop0): hash table key at wrong offset: should be at 7819474380466785382
  u64s 7 type dirent 4098:8977922886548783724:U32_MAX len 0 ver 0: file0 -> 4099 type reg, fixing
bcachefs (loop0): check_dirents requires second pass
bcachefs (loop0): directory with missing backpointer
  u64s 7 type dirent 4096:139537437271509772:U32_MAX len 0 ver 0: file0 -> 4098 type dir
  inum: 4098:4294967295 
    mode=40600
    flags=(4300000)
    journal_seq=16
    hash_seed=8dc72ab3fdf74724
    hash_type=siphash
    bi_size=0
    bi_sectors=0
    bi_version=0
    bi_atime=35328672594307541
    bi_ctime=35328672594307541
    bi_mtime=35328672594307541
    bi_otime=35328672594307541
    bi_uid=0
    bi_gid=0
    bi_nlink=0
    bi_generation=0
    bi_dev=0
    bi_data_checksum=0
    bi_compression=0
    bi_project=0
    bi_background_compression=0
    bi_data_replicas=0
    bi_promote_target=0
    bi_foreground_target=0
    bi_background_target=0
    bi_erasure_code=0
    bi_fields_set=0
    bi_dir=0
    bi_dir_offset=0
    bi_subvol=0
    bi_parent_subvol=0
    bi_nocow=0
    bi_depth=0
    bi_inodes_32bit=0
    bi_casefold=0, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 8 type dirent 4096:888293352835242737:U32_MAX len 0 ver 0: lost+found -> 4097 type dir, fixing
==================================================================
BUG: KASAN: use-after-free in check_dirent fs/bcachefs/fsck.c:2300 [inline]
BUG: KASAN: use-after-free in bch2_check_dirents+0x1efd/0x3390 fs/bcachefs/fsck.c:2326
Read of size 1 at addr ffff8880548e3070 by task syz.0.0/5329

CPU: 0 UID: 0 PID: 5329 Comm: syz.0.0 Not tainted 6.16.0-rc1-syzkaller-00239-g08215f5486ec #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 check_dirent fs/bcachefs/fsck.c:2300 [inline]
 bch2_check_dirents+0x1efd/0x3390 fs/bcachefs/fsck.c:2326
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
 bch2_fs_recovery+0x25fd/0x3950 fs/bcachefs/recovery.c:989
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1203
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4c8f1900ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f4c8b5d3e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4c8b5d3ef0 RCX: 00007f4c8f1900ca
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 00007f4c8b5d3eb0
RBP: 00002000000000c0 R08: 00007f4c8b5d3ef0 R09: 0000000000818001
R10: 0000000000818001 R11: 0000000000000246 R12: 0000200000000080
R13: 00007f4c8b5d3eb0 R14: 0000000000005974 R15: 0000200000000480
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x548e3
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 0000000000000000 ffffea00015238c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 5, migratetype Unmovable, gfp_mask 0x42800(GFP_NOWAIT|__GFP_COMP), pid 5329, tgid 5327 (syz.0.0), ts 75236194250, free_ts 77045434473
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 __alloc_pages_noprof+0xa/0x30 mm/page_alloc.c:4993
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x85/0x210 mm/slub.c:4272
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4300
 __do_kmalloc_node mm/slub.c:4316 [inline]
 __kvmalloc_node_noprof+0x6d/0x5f0 mm/slub.c:5015
 btree_bounce_alloc fs/bcachefs/btree_io.c:127 [inline]
 bch2_btree_node_read_done+0x2ecf/0x51f0 fs/bcachefs/btree_io.c:1276
 btree_node_read_work+0x426/0xe30 fs/bcachefs/btree_io.c:1411
 bch2_btree_node_read+0x887/0x2a00 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1877 [inline]
 bch2_btree_root_read+0x5f0/0x760 fs/bcachefs/btree_io.c:1899
 read_btree_roots+0x2c2/0x880 fs/bcachefs/recovery.c:604
 bch2_fs_recovery+0x2574/0x3950 fs/bcachefs/recovery.c:979
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1203
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
page last free pid 5329 tgid 5327 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_pages_ok+0xa44/0xc20 mm/page_alloc.c:1424
 __folio_put+0x21b/0x2c0 mm/swap.c:112
 folio_put include/linux/mm.h:1356 [inline]
 free_large_kmalloc+0x145/0x200 mm/slub.c:4768
 btree_bounce_free fs/bcachefs/btree_io.c:115 [inline]
 btree_node_sort+0x117f/0x1760 fs/bcachefs/btree_io.c:383
 bch2_btree_post_write_cleanup+0x11f/0xad0 fs/bcachefs/btree_io.c:2594
 bch2_btree_node_prep_for_write+0x337/0x650 fs/bcachefs/btree_trans_commit.c:95
 bch2_trans_lock_write+0x669/0xba0 fs/bcachefs/btree_trans_commit.c:131
 do_bch2_trans_commit fs/bcachefs/btree_trans_commit.c:847 [inline]
 __bch2_trans_commit+0x2829/0x8880 fs/bcachefs/btree_trans_commit.c:1079
 bch2_trans_commit fs/bcachefs/btree_update.h:242 [inline]
 check_dirent fs/bcachefs/fsck.c:2295 [inline]
 bch2_check_dirents+0x1cdf/0x3390 fs/bcachefs/fsck.c:2326
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
 bch2_fs_recovery+0x25fd/0x3950 fs/bcachefs/recovery.c:989
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1203
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885

Memory state around the buggy address:
 ffff8880548e2f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880548e2f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880548e3000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff8880548e3080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880548e3100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================