general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 PID: 6226 Comm: syz.1.120 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:percpu_ref_kill_and_confirm+0xf1/0x130 lib/percpu-refcount.c:392 Code: 01 4c 8d 63 08 4c 89 e0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 e7 e8 ee ef ac fd 4d 8b 24 24 49 83 c4 08 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 d0 ef ac fd 49 8b 14 24 48 c7 c7 RSP: 0018:ffffc9000babf9c8 EFLAGS: 00010002 RAX: 0000000000000001 RBX: ffff888026664040 RCX: 0000000000080000 RDX: ffffc9000cf92000 RSI: 0000000000001493 RDI: 0000000000001494 RBP: 1ffff11004ccc808 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52001757f14 R12: 0000000000000008 R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000a06 FS: 00007f01a512d6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c42812b CR3: 0000000023af5000 CR4: 00000000003526e0 Call Trace: percpu_ref_kill include/linux/percpu-refcount.h:149 [inline] mddev_suspend+0x1b0/0x5b0 drivers/md/md.c:450 mddev_create_serial_pool+0x282/0x470 drivers/md/md.c:219 backlog_store+0x382/0x4f0 drivers/md/md-bitmap.c:2592 md_attr_store+0x196/0x380 drivers/md/md.c:5630 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352 call_write_iter include/linux/fs.h:2018 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x474/0x9a0 fs/read_write.c:584 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f01a419e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f01a512d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f01a4425fa0 RCX: 00007f01a419e159 RDX: 0000000000000005 RSI: 0000200000000e00 RDI: 0000000000000009 RBP: 00007f01a4235024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f01a4426038 R14: 00007f01a4425fa0 R15: 00007ffe161ab678 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:percpu_ref_kill_and_confirm+0xf1/0x130 lib/percpu-refcount.c:392 Code: 01 4c 8d 63 08 4c 89 e0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 e7 e8 ee ef ac fd 4d 8b 24 24 49 83 c4 08 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 d0 ef ac fd 49 8b 14 24 48 c7 c7 RSP: 0018:ffffc9000babf9c8 EFLAGS: 00010002 RAX: 0000000000000001 RBX: ffff888026664040 RCX: 0000000000080000 RDX: ffffc9000cf92000 RSI: 0000000000001493 RDI: 0000000000001494 RBP: 1ffff11004ccc808 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52001757f14 R12: 0000000000000008 R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000a06 FS: 00007f01a512d6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c42812b CR3: 0000000023af5000 CR4: 00000000003526e0 ---------------- Code disassembly (best guess): 0: 01 4c 8d 63 add %ecx,0x63(%rbp,%rcx,4) 4: 08 4c 89 e0 or %cl,-0x20(%rcx,%rcx,4) 8: 48 c1 e8 03 shr $0x3,%rax c: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 11: 74 08 je 0x1b 13: 4c 89 e7 mov %r12,%rdi 16: e8 ee ef ac fd call 0xfdacf009 1b: 4d 8b 24 24 mov (%r12),%r12 1f: 49 83 c4 08 add $0x8,%r12 23: 4c 89 e0 mov %r12,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 4c 89 e7 mov %r12,%rdi 34: e8 d0 ef ac fd call 0xfdacf009 39: 49 8b 14 24 mov (%r12),%rdx 3d: 48 rex.W 3e: c7 .byte 0xc7 3f: c7 .byte 0xc7