bcachefs (loop0): Detected missing backpointers in bucket 34, now have 1/128 with missing BUG: unable to handle page fault for address: ffffed120618f45c #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] SMP KASAN PTI CPU: 0 UID: 0 PID: 6224 Comm: bch-copygc/loop Not tainted 6.16.0-rc5-syzkaller-00025-gd006330be3f7 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0x9b/0x2c0 mm/kasan/generic.c:189 Code: 01 00 00 00 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb <41> 80 3b 00 0f 85 de 01 00 00 49 ff c3 48 ff c3 75 ee e9 21 01 00 RSP: 0018:ffffc90002f17528 EFLAGS: 00010286 RAX: 0000000200000001 RBX: ffffffffffffffff RCX: ffffffff844716b1 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff889030c7a2e0 RBP: ffffc90002f17930 R08: ffff889030c7a2e7 R09: 1ffff1120618f45c R10: dffffc0000000000 R11: ffffed120618f45c R12: 0000000000000001 R13: dffffc0000000000 R14: ffffed120618f45d R15: 1ffff1120618f45c FS: 0000000000000000(0000) GS:ffff888125c4f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffed120618f45c CR3: 0000000022bdc000 CR4: 00000000003526f0 Call Trace: 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+0xfb1/0x4380 fs/bcachefs/movinggc.c:221 bch2_copygc_thread+0x97a/0xe00 fs/bcachefs/movinggc.c:409 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Modules linked in: CR2: ffffed120618f45c ---[ end trace 0000000000000000 ]--- RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0x9b/0x2c0 mm/kasan/generic.c:189 Code: 01 00 00 00 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb <41> 80 3b 00 0f 85 de 01 00 00 49 ff c3 48 ff c3 75 ee e9 21 01 00 RSP: 0018:ffffc90002f17528 EFLAGS: 00010286 RAX: 0000000200000001 RBX: ffffffffffffffff RCX: ffffffff844716b1 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff889030c7a2e0 RBP: ffffc90002f17930 R08: ffff889030c7a2e7 R09: 1ffff1120618f45c R10: dffffc0000000000 R11: ffffed120618f45c R12: 0000000000000001 R13: dffffc0000000000 R14: ffffed120618f45d R15: 1ffff1120618f45c FS: 0000000000000000(0000) GS:ffff888125c4f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffed120618f45c CR3: 0000000022bdc000 CR4: 00000000003526f0 ---------------- Code disassembly (best guess), 7 bytes skipped: 0: df 4d 8d fisttps -0x73(%rbp) 3: 34 19 xor $0x19,%al 5: 4d 89 f4 mov %r14,%r12 8: 4d 29 dc sub %r11,%r12 b: 49 83 fc 10 cmp $0x10,%r12 f: 7f 29 jg 0x3a 11: 4d 85 e4 test %r12,%r12 14: 0f 84 41 01 00 00 je 0x15b 1a: 4c 89 cb mov %r9,%rbx 1d: 48 f7 d3 not %rbx 20: 4c 01 fb add %r15,%rbx * 23: 41 80 3b 00 cmpb $0x0,(%r11) <-- trapping instruction 27: 0f 85 de 01 00 00 jne 0x20b 2d: 49 ff c3 inc %r11 30: 48 ff c3 inc %rbx 33: 75 ee jne 0x23 35: e9 .byte 0xe9 36: 21 01 and %eax,(%rcx)