syzbot has found a reproducer for the following issue on: HEAD commit: 7482bb149b9f Merge branch 'for-next/core' into for-kernelci git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci console output: https://syzkaller.appspot.com/x/log.txt?x=12bf4a8c580000 kernel config: https://syzkaller.appspot.com/x/.config?x=3c06e3e2454512b3 dashboard link: https://syzkaller.appspot.com/bug?extid=3168625f36f4a539237e compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14f63f70580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16bf4a8c580000
Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/f623d741d651/disk-7482bb14.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/483e23ae71b1/vmlinux-7482bb14.xz kernel image: https://storage.googleapis.com/syzbot-assets/79b5baaa1b50/Image-7482bb14.gz.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/f9688b789a98/mount_0.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3168625f36f4a5392...@syzkaller.appspotmail.com bcachefs (loop1): Detected missing backpointers in bucket 34, now have 1/128 with missing Unable to handle kernel paging request at virtual address ffff60021a145c30 KASAN: probably wild-memory-access in range [0xffff0010d0a2e180-0xffff0010d0a2e187] Mem abort info: ESR = 0x0000000096000005 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x05: level 1 translation fault Data abort info: ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000207144000 [ffff60021a145c30] pgd=0000000000000000, p4d=000000023397b003, pud=0000000000000000 Internal error: Oops: 0000000096000005 [#1] SMP Modules linked in: CPU: 0 UID: 0 PID: 6717 Comm: bch-copygc/loop Not tainted 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline] pc : bch2_bucket_bitmap_test fs/bcachefs/backpointers.h:194 [inline] pc : bch2_bucket_is_movable fs/bcachefs/movinggc.c:78 [inline] pc : bch2_copygc_get_buckets fs/bcachefs/movinggc.c:157 [inline] pc : bch2_copygc+0xab4/0x3460 fs/bcachefs/movinggc.c:221 lr : rcu_read_unlock include/linux/rcupdate.h:873 [inline] lr : class_rcu_destructor include/linux/rcupdate.h:1155 [inline] lr : bch2_dev_tryget_noerror fs/bcachefs/sb-members.h:241 [inline] lr : bch2_dev_tryget fs/bcachefs/sb-members.h:245 [inline] lr : bch2_bucket_is_movable fs/bcachefs/movinggc.c:74 [inline] lr : bch2_copygc_get_buckets fs/bcachefs/movinggc.c:157 [inline] lr : bch2_copygc+0xa7c/0x3460 fs/bcachefs/movinggc.c:221 sp : ffff80009e0c74c0 x29: ffff80009e0c7920 x28: 0000008000000022 x27: ffff80009e0c76c8 x26: dfff800000000000 x25: ffff80009e0c7cf8 x24: 0000000000000000 x23: ffff0000f5890000 x22: 0000000000000000 x21: ffff0000f2d00000 x20: ffff0010d0a2e180 x19: ffff0000df09cc28 x18: 00000000ffffffff x17: ffff800093363000 x16: ffff80008aefcb18 x15: 0000000000000001 x14: 1fffe0001eb12008 x13: 0000000000000000 x12: 0000000000000000 x11: ffff60001eb12009 x10: 0000000000ff0100 x9 : 0000001000000000 x8 : 1fffe0021a145c30 x7 : ffff800082a0df54 x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800082a0edd4 x2 : 0000000000000001 x1 : 0000000000000080 x0 : ffff0000cc76bd00 Call trace: generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline] (P) bch2_bucket_bitmap_test fs/bcachefs/backpointers.h:194 [inline] (P) bch2_bucket_is_movable fs/bcachefs/movinggc.c:78 [inline] (P) bch2_copygc_get_buckets fs/bcachefs/movinggc.c:157 [inline] (P) bch2_copygc+0xab4/0x3460 fs/bcachefs/movinggc.c:221 (P) bch2_copygc_thread+0x898/0xd8c fs/bcachefs/movinggc.c:409 kthread+0x5fc/0x75c kernel/kthread.c:464 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847 Code: d343fd29 927da529 8b090114 d343fe88 (387a6908) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: d343fd29 lsr x9, x9, #3 4: 927da529 and x9, x9, #0x1ffffffffff8 8: 8b090114 add x20, x8, x9 c: d343fe88 lsr x8, x20, #3 * 10: 387a6908 ldrb w8, [x8, x26] <-- trapping instruction --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.
