Hi Mike! I just bisected a kernel issue on ia64 which leads to the kernel hanging very early when booting on an HP RX2600 server (also verified to hang on other ia64 machines): Loading Linux 5.8.0-12299-g00e4db51259a ... Loading initial ramdisk ... [ 0.000000] Linux version 5.8.0-12299-g00e4db51259a (root@glendronach) (gcc (Debian 10.2.0-3) 10.2.0, GNU ld (GNU Binutils for Debian) 2.35) #5 SMP Tue Aug 11 15:33:11 CEST 2020 [ 0.000000] efi: EFI v2.00 by HP [ 0.000000] efi: SALsystab=0x3ee7a000 ACPI 2.0=0x3fde4000 ESI=0x3ee7b000 SMBIOS=0x3ee7c000 HCDP=0x3fde2000 [ 0.000000] PCDP: v3 at 0x3fde2000 [ 0.000000] earlycon: uart8250 at MMIO 0x0000000088033000 (options '115200n8') [ 0.000000] printk: bootconsole [uart8250] enabled [ 0.000000] ACPI: Early table checksum verification disabled [ 0.000000] ACPI: RSDP 0x000000003FDE4000 000028 (v02 HP ) [ 0.000000] ACPI: XSDT 0x000000003FDE402C 0000A4 (v01 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: FACP 0x000000003FDF6A08 0000F4 (v03 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: DSDT 0x000000003FDE41C8 00E566 (v01 HP rx2660 00000007 INTL 20050309) [ 0.000000] ACPI: FACS 0x000000003FDF6B00 000040 [ 0.000000] ACPI: SPCR 0x000000003FDF6B40 000050 (v01 HP 00000000 HP 00000000) [ 0.000000] ACPI: DBGP 0x000000003FDF6B90 000034 (v01 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: APIC 0x000000003FDF6FB0 0000C8 (v01 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: SPMI 0x000000003FDF6BC8 000050 (v04 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: CPEP 0x000000003FDF6E80 000034 (v01 HP rx2660 00000000 HP 00000000) [ 0.000000] ACPI: SSDT 0x000000003FDF2738 0004B3 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF2BF8 000456 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF3058 000EB8 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF3F18 000EB8 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF4DD8 000866 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF5648 000EB8 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF6508 000138 (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF6648 00013C (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF6788 00013C (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: SSDT 0x000000003FDF68C8 00013C (v01 HP rx2660 00000006 INTL 20050309) [ 0.000000] ACPI: Local APIC address (____ptrval____) [ 0.000000] 4 CPUs available, 4 CPUs total [ 0.000000] SMP: Allowing 4 CPUs, 0 hotplug CPUs [ 0.000000] Initial ramdisk at: 0xe00000002e368000 (9818100 bytes) [ 0.000000] SAL 3.20: HP version 4.4 [ 0.000000] SAL Platform features: [ 0.000000] None [ 0.000000] SAL: AP wakeup using external interrupt vector 0xff [ 0.000000] MCA related initialization done [ 0.000000] Virtual mem_map starts at 0x(____ptrval____) [ 0.000000] Zone ranges: [ 0.000000] DMA32 [mem 0x0000000001000000-0x00000000ffffffff] [ 0.000000] Normal [mem 0x0000000100000000-0x000001007fffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000001000000-0x000000003e67ffff] [ 0.000000] node 0: [mem 0x000000003eaec000-0x000000003ee77fff] [ 0.000000] node 0: [mem 0x000000003fc00000-0x000000003fd77fff] [ 0.000000] node 0: [mem 0x000000003fddc000-0x000000003fddffff] [ 0.000000] node 0: [mem 0x0000010040000000-0x000001007f1fbfff] [ 0.000000] node 0: [mem 0x000001007f200000-0x000001007fffffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000001000000-0x000001007fffffff] Bisecting the problem lead to your change as mentioned in the topic: 974b9b2c68f3d35a65e80af9657fe378d2439b60 is the first bad commit commit 974b9b2c68f3d35a65e80af9657fe378d2439b60 Author: Mike Rapoport <rppt@xxxxxxxxxxxxx> Date: Mon Jun 8 21:33:10 2020 -0700 mm: consolidate pte_index() and pte_offset_*() definitions All architectures define pte_index() as (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1) and all architectures define pte_offset_kernel() as an entry in the array of PTEs indexed by the pte_index(). For the most architectures the pte_offset_kernel() implementation relies on the availability of pmd_page_vaddr() that converts a PMD entry value to the virtual address of the page containing PTEs array. Let's move x86 definitions of the PTE accessors to the generic place in <linux/pgtable.h> and then simply drop the respective definitions from the other architectures. The architectures that didn't provide pmd_page_vaddr() are updated to have that defined. The generic implementation of pte_offset_kernel() can be overridden by an architecture and alpha makes use of this because it has special ordering requirements for its version of pte_offset_kernel(). Any suggestions what could be the problem? Thanks, Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - glaubitz@xxxxxxxxxx `. `' Freie Universitaet Berlin - glaubitz@xxxxxxxxxxxxxxxxxxx `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913