bcachefs (loop0): error validating btree node at btree extents level 0/0
  u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq c6c25c03258c59c5 written 48 min_key 0:36028797018963968:0 durability: 1 ptr: 0:27:0 gen 0  
  node offset 8/48 bset u64s 2097 bset byte offset 40: bad k->u64s 0 (min 3 max 253), fixing
invalid bkey in btree_node btree=extents level=0: u64s 10 type deleted 8825211592396076079:4100:0 len 0 ver 0: 
  snapshot == 0: delete?, fixing
bcachefs (loop0): error validating btree node at btree extents level 0/0
  u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq c6c25c03258c59c5 written 48 min_key 0:36028797018963968:0 durability: 1 ptr: 0:27:0 gen 0  
  node offset 8/48 bset u64s 2088 bset byte offset 360: bad k->u64s 0 (min 3 max 253), fixing
==================================================================
BUG: KASAN: slab-out-of-bounds in bkey_packed_valid+0x488/0x6c0 fs/bcachefs/btree_io.c:865
Read of size 1 at addr ffff8880530e0240 by task kworker/0:1H/37

CPU: 0 UID: 0 PID: 37 Comm: kworker/0:1H Not tainted 6.14.0-rc4-syzkaller-00282-g1973160c90d7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: bcachefs_btree_read_complete btree_node_read_work
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
 bkey_packed_valid+0x488/0x6c0 fs/bcachefs/btree_io.c:865
 validate_bset_keys+0xeb5/0x1af0 fs/bcachefs/btree_io.c:987
 bch2_btree_node_read_done+0x2298/0x6180 fs/bcachefs/btree_io.c:1164
 btree_node_read_work+0x6dc/0x1380 fs/bcachefs/btree_io.c:1358
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3319
 worker_thread+0x870/0xd30 kernel/workqueue.c:3400
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

The buggy address belongs to the object at ffff8880530e0000
 which belongs to the cache radix_tree_node of size 576
The buggy address is located 0 bytes to the right of
 allocated 576-byte region [ffff8880530e0000, ffff8880530e0240)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x530e0
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888040dddf81
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801b04fdc0 dead000000000122 0000000000000000
raw: 0000000000000000 00000000000b000b 00000000f5000000 ffff888040dddf81
head: 04fff00000000040 ffff88801b04fdc0 dead000000000122 0000000000000000
head: 0000000000000000 00000000000b000b 00000000f5000000 ffff888040dddf81
head: 04fff00000000001 ffffea00014c3801 ffffffffffffffff 0000000000000000
head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Reclaimable, gfp_mask 0x52810(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_RECLAIMABLE), pid 5325, tgid 5324 (syz.0.0), ts 68315596546, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4739
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab+0x8f/0x3a0 mm/slub.c:2587
 new_slab mm/slub.c:2640 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
 __slab_alloc+0x58/0xa0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 kmem_cache_alloc_lru_noprof+0x26c/0x390 mm/slub.c:4183
 xas_alloc lib/xarray.c:377 [inline]
 xas_create+0x10d0/0x1ae0 lib/xarray.c:684
 xas_store+0x96/0x1870 lib/xarray.c:794
 shmem_add_to_page_cache+0x89d/0xcc0 mm/shmem.c:897
 shmem_alloc_and_add_folio+0x968/0x1090 mm/shmem.c:1928
 shmem_get_folio_gfp+0x621/0x1840 mm/shmem.c:2522
 shmem_get_folio mm/shmem.c:2628 [inline]
 shmem_write_begin+0x165/0x350 mm/shmem.c:3278
 generic_perform_write+0x346/0x990 mm/filemap.c:4189
 shmem_file_write_iter+0xf9/0x120 mm/shmem.c:3454
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880530e0100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880530e0180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880530e0200: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                           ^
 ffff8880530e0280: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8880530e0300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================