bcachefs (loop0): Detected missing backpointers in bucket 34, now have 1/128 with missing
  running recovery pass check_extents_to_backpointers (17), currently at resume_logged_ops (39)
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: slab-use-after-free in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
BUG: KASAN: slab-use-after-free in bch2_bucket_bitmap_test fs/bcachefs/backpointers.h:194 [inline]
BUG: KASAN: slab-use-after-free in bch2_bucket_is_movable fs/bcachefs/movinggc.c:78 [inline]
BUG: KASAN: slab-use-after-free in bch2_copygc_get_buckets fs/bcachefs/movinggc.c:157 [inline]
BUG: KASAN: slab-use-after-free in bch2_copygc+0x105d/0x4510 fs/bcachefs/movinggc.c:221
Read of size 8 at addr ffff888011d39780 by task bch-copygc/loop/5366

CPU: 0 UID: 0 PID: 5366 Comm: bch-copygc/loop Not tainted 6.16.0-syzkaller-12288-g2b38afce25c4 #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:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 bch2_bucket_bitmap_test fs/bcachefs/backpointers.h:194 [inline]
 bch2_bucket_is_movable fs/bcachefs/movinggc.c:78 [inline]
 bch2_copygc_get_buckets fs/bcachefs/movinggc.c:157 [inline]
 bch2_copygc+0x105d/0x4510 fs/bcachefs/movinggc.c:221
 bch2_copygc_thread+0x97a/0xe00 fs/bcachefs/movinggc.c:409
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5366:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4365 [inline]
 __kvmalloc_node_noprof+0x30d/0x5f0 mm/slub.c:5052
 kvmalloc_array_node_noprof include/linux/slab.h:1065 [inline]
 bch2_bucket_bitmap_set+0x9a/0x1d0 fs/bcachefs/backpointers.c:1351
 check_bucket_backpointer_mismatch+0x1bdf/0x23a0 fs/bcachefs/backpointers.c:964
 check_bucket_backpointer_pos_mismatch fs/bcachefs/backpointers.c:1193 [inline]
 bch2_check_bucket_backpointer_mismatch+0x36c/0x690 fs/bcachefs/backpointers.c:1205
 __bch2_move_data_phys+0x17a7/0x1c50 fs/bcachefs/move.c:922
 bch2_evacuate_bucket+0x228/0x3a0 fs/bcachefs/move.c:1082
 bch2_copygc+0x3be3/0x4510 fs/bcachefs/movinggc.c:234
 bch2_copygc_thread+0x97a/0xe00 fs/bcachefs/movinggc.c:409
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888011d39780
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
 freed 16-byte region [ffff888011d39780, ffff888011d39790)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d39
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801a441640 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080800080 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 5333, tgid 5333 (syz-executor), ts 66664776728, free_ts 66655136187
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_pages_slowpath+0x2fe/0xce0 mm/page_alloc.c:4679
 __alloc_frozen_pages_noprof+0x319/0x370 mm/page_alloc.c:5161
 alloc_slab_page mm/slub.c:2489 [inline]
 allocate_slab+0x65/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 __kmalloc_cache_node_noprof+0x29a/0x3d0 mm/slub.c:4404
 kmalloc_node_noprof include/linux/slab.h:928 [inline]
 hugetlb_cgroup_css_alloc+0x165/0xae0 mm/hugetlb_cgroup.c:168
 css_create kernel/cgroup/cgroup.c:5669 [inline]
 cgroup_apply_control_enable+0x3d1/0xa80 kernel/cgroup/cgroup.c:3289
 cgroup_mkdir+0xc40/0xe60 kernel/cgroup/cgroup.c:5893
 kernfs_iop_mkdir+0x20e/0x350 fs/kernfs/dir.c:1268
 vfs_mkdir+0x306/0x510 fs/namei.c:4366
 do_mkdirat+0x247/0x590 fs/namei.c:4399
 __do_sys_mkdirat fs/namei.c:4416 [inline]
 __se_sys_mkdirat fs/namei.c:4414 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4414
 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
page last free pid 5333 tgid 5333 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 __slab_free+0x303/0x3c0 mm/slub.c:4591
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236
 getname_flags+0xb8/0x540 fs/namei.c:146
 user_path_at+0x24/0x60 fs/namei.c:3126
 __do_sys_pivot_root fs/namespace.c:4661 [inline]
 __se_sys_pivot_root+0x18f/0xc20 fs/namespace.c:4650
 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

Memory state around the buggy address:
 ffff888011d39680: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
 ffff888011d39700: fa fb fc fc fa fb fc fc 00 00 fc fc 00 00 fc fc
>ffff888011d39780: fb fb fc fc 00 00 fc fc fa fb fc fc fa fb fc fc
                   ^
 ffff888011d39800: 00 00 fc fc fa fb fc fc fa fb fc fc fc fc fc fc
 ffff888011d39880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================