> -----Original Message-----
> Creating vmcore from sadump by makedumpfile fails with the following
> error messages since kernel-4.19 with PTI (Page Table Isolation)
> enabled:
> 
>   __vtop4_x86_64: Can't get a valid pte.
>   readmem: Can't convert a virtual address(ffffffffb2986000) to physical 
> address.
>   readmem: type_addr: 0, addr:ffffffffb2986000, size:8
>   per_cpu_init: Can't read __per_cpu_load memory.
> 
> This is caused by the following patch:
> https://github.com/torvalds/linux/commit/c40a56a7818cfe735fc93a69e1875f8bba834483
> 
> The above patch clears _PAGE_PRESENT bit of __per_cpu_load memory, so
> __vtop4_x86_64 fails to convert the virtual address of the
> __per_cpu_load.
> 
> To fix this issue, this patch changes sanity check of per_cpu_ptr()
> to use address of the __per_cpu_load instead of data of the memory.
> 
> Signed-off-by: Kazuya Saito <saito.kaz...@fujitsu.com>
> Signed-off-by: Kiyotaka Nakamura <k...@fujitsu.com>
> ---
>  sadump_info.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/sadump_info.c b/sadump_info.c
> index 46867ce..72a077b 100644
> --- a/sadump_info.c
> +++ b/sadump_info.c
> @@ -1732,11 +1732,11 @@ per_cpu_init(void)
>               return FALSE;
>       }
> 
> -     if (!readmem(VADDR, SYMBOL(__per_cpu_load), &si->__per_cpu_load,
> -                  sizeof(unsigned long))) {
> -             ERRMSG("Can't read __per_cpu_load memory.\n");
> +     if (SYMBOL(__per_cpu_load) == NOT_FOUND_SYMBOL) {
> +             ERRMSG("Can't find __per_cpu_load symbol.\n");
>               return FALSE;
>       }
> +     si->__per_cpu_load = SYMBOL(__per_cpu_load);
> 
>       DEBUG_MSG("sadump: __per_cpu_load: %#lx\n", si->__per_cpu_load);
>       DEBUG_MSG("sadump: __per_cpu_offset: LENGTH: %ld\n",
> --
> 2.12.3
> 

Hi,

The patch looks good to me, applied.
https://github.com/makedumpfile/makedumpfile/commit/c9e078531efaffbe6f780221d40bdac21a84855b

Thanks,
Kazu


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