Might be worth looking into from the dm side. ----- Forwarded message from syzbot <[email protected]> -----
Date: Sat, 24 Oct 2026 14:37:38 -0700 From: syzbot <[email protected]> Subject: [syzbot] [block?] divide error in blk_stack_limits To: [email protected], [email protected], [email protected], [email protected] Hello, syzbot found the following issue on: HEAD commit: f47d223627f8 Merge tag 'vfs-7.4-rc1.sync_close' of git://g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1633b921580000 kernel config: https://syzkaller.appspot.com/x/.config?x=97e47414c855a3d8 dashboard link: https://syzkaller.appspot.com/bug?extid=1288484b13bf6af3620d compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=177c720d580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c0f4e1580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f47d2236.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a94d6307dbbf/vmlinux-f47d2236.xz kernel image: https://storage.googleapis.com/syzbot-assets/f114012b9c35/bzImage-f47d2236.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: [email protected] Oops: divide error: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5481 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:queue_limit_discard_alignment block/blk-settings.c:645 [inline] RIP: 0010:blk_stack_limits+0x1105/0x2d00 block/blk-settings.c:916 Code: 68 48 4c 89 e8 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 7c 18 00 00 45 8b 65 00 c7 44 24 10 00 00 00 00 eb 5f 48 8b 44 24 48 31 d2 <41> f7 f5 44 01 e9 29 d1 89 c8 31 d2 41 f7 f5 48 8b 44 24 08 4c 8d RSP: 0018:ffffc90001c0f4f8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000 RBP: ffffc90001c0f850 R08: ffffc90001c0f7e0 R09: 1ffffffff37b4dc0 R10: dffffc0000000000 R11: ffffffff88a11a10 R12: 00000000ffffffff R13: 0000000000000000 R14: 1ffff92000381f0a R15: ffffc90001c0f854 FS: 0000555570175500(0000) GS:ffff88808b0b0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa930071220 CR3: 000000003cf9f000 CR4: 0000000000352ef0 Call Trace: <TASK> dm_calculate_queue_limits+0x70c/0x1510 drivers/md/dm-table.c:1823 dm_setup_md_queue+0x199/0x4f0 drivers/md/dm.c:2618 table_load+0x4fd/0x8a0 drivers/md/dm-ioctl.c:1661 ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline] dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa93019f559 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:00007ffce7b56638 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fa930425fa0 RCX: 00007fa93019f559 RDX: 0000200000000640 RSI: 00000000c138fd09 RDI: 0000000000000003 RBP: 00007fa930236b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa930425fac R14: 00007fa930425fa0 R15: 00007fa930425fa0 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:queue_limit_discard_alignment block/blk-settings.c:645 [inline] RIP: 0010:blk_stack_limits+0x1105/0x2d00 block/blk-settings.c:916 Code: 68 48 4c 89 e8 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 7c 18 00 00 45 8b 65 00 c7 44 24 10 00 00 00 00 eb 5f 48 8b 44 24 48 31 d2 <41> f7 f5 44 01 e9 29 d1 89 c8 31 d2 41 f7 f5 48 8b 44 24 08 4c 8d RSP: 0018:ffffc90001c0f4f8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000 RBP: ffffc90001c0f850 R08: ffffc90001c0f7e0 R09: 1ffffffff37b4dc0 R10: dffffc0000000000 R11: ffffffff88a11a10 R12: 00000000ffffffff R13: 0000000000000000 R14: 1ffff92000381f0a R15: ffffc90001c0f854 FS: 0000555570175500(0000) GS:ffff88808b0b0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa930071220 CR3: 000000003cf9f000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 68 48 4c 89 e8 push $0xffffffffe8894c48 5: 48 c1 e8 03 shr $0x3,%rax 9: 0f b6 04 18 movzbl (%rax,%rbx,1),%eax d: 84 c0 test %al,%al f: 0f 85 7c 18 00 00 jne 0x1891 15: 45 8b 65 00 mov 0x0(%r13),%r12d 19: c7 44 24 10 00 00 00 movl $0x0,0x10(%rsp) 20: 00 21: eb 5f jmp 0x82 23: 48 8b 44 24 48 mov 0x48(%rsp),%rax 28: 31 d2 xor %edx,%edx * 2a: 41 f7 f5 div %r13d <-- trapping instruction 2d: 44 01 e9 add %r13d,%ecx 30: 29 d1 sub %edx,%ecx 32: 89 c8 mov %ecx,%eax 34: 31 d2 xor %edx,%edx 36: 41 f7 f5 div %r13d 39: 48 8b 44 24 08 mov 0x8(%rsp),%rax 3e: 4c rex.WR 3f: 8d .byte 0x8d --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at [email protected]. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup ----- End forwarded message -----
