bcachefs (loop0): journal_replay... done
bcachefs (loop0): check_lrus...
bcachefs (loop0): incorrect lru entry: lru fragmentation time 134217728
  u64s 5 type set 18446462598867058688:34:0 len 0 ver 0
  for u64s 13 type alloc_v4 0:34:0 len 0 ver 0: 
    gen 0 oldest_gen 0 data_type need_discard
    journal_seq_nonempty 5
    journal_seq_empty    134217728
    need_discard         1
    need_inc_gen         1
    dirty_sectors        0
    stripe_sectors       0
    cached_sectors       0
    stripe               0
    stripe_redundancy    0
    io_time[READ]        1
    io_time[WRITE]       512
    fragmentation     0
    bp_start          8
  , fixing
 done
bcachefs (loop0): check_backpointers_to_extents...
bcachefs (loop0): backpointer doesn't match btree node it points to:
  u64s 9 type backpointer 0:7077888:0 len 0 ver 0: bucket=0:27:0 btree=extents level=1 data_type=btree suboffset=0 len=256 gen=0 pos=SPOS_MAX
  u64s 5 type btree_ptr SPOS_MAX len 0 ver 0, fixing
bcachefs (loop0): backpointer doesn't match extent it points to:
  u64s 9 type backpointer 0:8912896:0 len 0 ver 0: bucket=0:34:0 btree=extents level=0 data_type=user suboffset=0 len=8 gen=0 pos=4099:8:U32_MAX
  u64s 5 type deleted 4099:8:U32_MAX len 0 ver 0, fixing
bcachefs (loop0): backpointer doesn't match extent it points to:
  u64s 9 type backpointer 0:8921088:0 len 0 ver 0: bucket=0:34:8 btree=extents level=0 data_type=user suboffset=0 len=8 gen=0 pos=536870913:24:U32_MAX
  u64s 5 type deleted 536870913:24:U32_MAX len 0 ver 0, fixing
 done
bcachefs (loop0): check_inodes... done
bcachefs (loop0): check_extents... done
bcachefs (loop0): check_dirents...
bcachefs (loop0): hash table key at wrong offset: btree dirents inode 4096 offset 189491840996961599, hashed to 2388083354671393909
  u64s 7 type dirent 4096:189491840996961599:U32_MAX len 0 ver 0: file0 -> 4098 type dir, fixing
bcachefs (loop0): hash table key at wrong offset: btree dirents inode 4096 offset 1896155912177158345, hashed to 5605613727555233146
  u64s 7 type dirent 4096:1896155912177158345:U32_MAX len 0 ver 0: file3 -> 536870913 type reg, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 7 type dirent 4096:2388083354671393909:U32_MAX len 0 ver 0: file0 -> 4098 type dir, fixing
bcachefs (loop0): hash table key at wrong offset: btree dirents inode 4096 offset 2695648408715017799, hashed to 152626200281515195
  u64s 7 type dirent 4096:2695648408715017799:U32_MAX len 0 ver 0: file2 -> 536870913 type reg, fixing
bcachefs (loop0): hash table key at wrong offset: btree dirents inode 4096 offset 4330382808765825483, hashed to 6345739775019248599
  u64s 7 type dirent 4096:4330382808765825483:U32_MAX len 0 ver 0: file1 -> 536870912 type reg, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 7 type dirent 4096:5605613727555233146:U32_MAX len 0 ver 0: file3 -> 536870913 type reg, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 7 type dirent 4096:6345739775019248599:U32_MAX len 0 ver 0: file1 -> 536870912 type reg, fixing
==================================================================
BUG: KASAN: use-after-free in check_dirent fs/bcachefs/fsck.c:2205 [inline]
BUG: KASAN: use-after-free in bch2_check_dirents+0x2aac/0x3b90 fs/bcachefs/fsck.c:2230
Read of size 1 at addr ffff888056523070 by task syz.0.0/5327

CPU: 0 UID: 0 PID: 5327 Comm: syz.0.0 Not tainted 6.15.0-rc1-syzkaller-00065-g3b07108ada81 #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 lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 check_dirent fs/bcachefs/fsck.c:2205 [inline]
 bch2_check_dirents+0x2aac/0x3b90 fs/bcachefs/fsck.c:2230
 bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:226
 bch2_run_recovery_passes+0x2ad/0xa90 fs/bcachefs/recovery_passes.c:285
 bch2_fs_recovery+0x292a/0x3e20 fs/bcachefs/recovery.c:936
 bch2_fs_start+0x310/0x620 fs/bcachefs/super.c:1069
 bch2_fs_get_tree+0x113e/0x18f0 fs/bcachefs/fs.c:2253
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
 do_mount fs/namespace.c:4219 [inline]
 __do_sys_mount fs/namespace.c:4430 [inline]
 __se_sys_mount+0x38c/0x400 fs/namespace.c:4407
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc52bf8e90a
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:00007fc5283d3e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fc5283d3ef0 RCX: 00007fc52bf8e90a
RDX: 0000200000000000 RSI: 0000200000000040 RDI: 00007fc5283d3eb0
RBP: 0000200000000000 R08: 00007fc5283d3ef0 R09: 0000000001000001
R10: 0000000001000001 R11: 0000000000000246 R12: 0000200000000040
R13: 00007fc5283d3eb0 R14: 0000000000005968 R15: 0000200000000300
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x56523
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 0000000000000000 ffffea00015948c8 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 0x52800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP), pid 5327, tgid 5324 (syz.0.0), ts 82747456424, free_ts 84176802338
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1717
 prep_new_page mm/page_alloc.c:1725 [inline]
 get_page_from_freelist+0x352b/0x36c0 mm/page_alloc.c:3652
 __alloc_frozen_pages_noprof+0x211/0x5b0 mm/page_alloc.c:4934
 __alloc_pages_noprof+0xa/0x30 mm/page_alloc.c:4968
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x92/0x210 mm/slub.c:4275
 __kmalloc_large_node_noprof+0x1a/0x80 mm/slub.c:4303
 __do_kmalloc_node mm/slub.c:4319 [inline]
 __kvmalloc_node_noprof+0x7c/0x5a0 mm/slub.c:5016
 btree_bounce_alloc fs/bcachefs/btree_io.c:124 [inline]
 bch2_btree_node_read_done+0x393c/0x62c0 fs/bcachefs/btree_io.c:1224
 btree_node_read_work+0x6cb/0x1400 fs/bcachefs/btree_io.c:1366
 bch2_btree_node_read+0x2427/0x29e0 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1797 [inline]
 bch2_btree_root_read+0x656/0x7e0 fs/bcachefs/btree_io.c:1819
 read_btree_roots+0x3d7/0xa80 fs/bcachefs/recovery.c:581
 bch2_fs_recovery+0x28e4/0x3e20 fs/bcachefs/recovery.c:928
 bch2_fs_start+0x310/0x620 fs/bcachefs/super.c:1069
 bch2_fs_get_tree+0x113e/0x18f0 fs/bcachefs/fs.c:2253
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
page last free pid 5327 tgid 5324 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_pages_ok+0xb1d/0xda0 mm/page_alloc.c:1437
 __folio_put+0x2b5/0x360 mm/swap.c:112
 folio_put include/linux/mm.h:1563 [inline]
 free_large_kmalloc+0x143/0x1e0 mm/slub.c:4771
 kfree+0x216/0x430 mm/slub.c:4839
 btree_bounce_free fs/bcachefs/btree_io.c:112 [inline]
 btree_node_sort+0x1124/0x1870 fs/bcachefs/btree_io.c:380
 bch2_btree_post_write_cleanup+0x11a/0xaa0 fs/bcachefs/btree_io.c:2508
 bch2_btree_node_prep_for_write+0x35a/0x670 fs/bcachefs/btree_trans_commit.c:93
 bch2_trans_lock_write+0x66f/0xb60 fs/bcachefs/btree_trans_commit.c:129
 do_bch2_trans_commit fs/bcachefs/btree_trans_commit.c:840 [inline]
 __bch2_trans_commit+0x3252/0x9da0 fs/bcachefs/btree_trans_commit.c:1050
 bch2_trans_commit fs/bcachefs/btree_update.h:195 [inline]
 check_dirent fs/bcachefs/fsck.c:2200 [inline]
 bch2_check_dirents+0x2801/0x3b90 fs/bcachefs/fsck.c:2230
 bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:226
 bch2_run_recovery_passes+0x2ad/0xa90 fs/bcachefs/recovery_passes.c:285
 bch2_fs_recovery+0x292a/0x3e20 fs/bcachefs/recovery.c:936
 bch2_fs_start+0x310/0x620 fs/bcachefs/super.c:1069
 bch2_fs_get_tree+0x113e/0x18f0 fs/bcachefs/fs.c:2253
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759

Memory state around the buggy address:
 ffff888056522f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888056522f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888056523000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff888056523080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888056523100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================