On 08/02/20 at 07:35pm, Mike Rapoport wrote:
> From: Mike Rapoport <r...@linux.ibm.com>
> 
> * Replace magic numbers with defines
> * Replace memblock_find_in_range() + memblock_reserve() with
>   memblock_phys_alloc_range()
> * Stop checking for low memory size in reserve_crashkernel_low(). The
>   allocation from limited range will anyway fail if there is no enough
>   memory, so there is no need for extra traversal of memblock.memory
> 
> Signed-off-by: Mike Rapoport <r...@linux.ibm.com>
> ---
>  arch/x86/kernel/setup.c | 40 ++++++++++++++--------------------------
>  1 file changed, 14 insertions(+), 26 deletions(-)

Applied this patch on top of 5.8, crashkernel reservation works well.
And the code change looks good.

Reviewed-by: Baoquan He <b...@redhat.com>

> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index d8de4053c5e8..d7ced6982524 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -419,13 +419,13 @@ static int __init reserve_crashkernel_low(void)
>  {
>  #ifdef CONFIG_X86_64
>       unsigned long long base, low_base = 0, low_size = 0;
> -     unsigned long total_low_mem;
> +     unsigned long low_mem_limit;
>       int ret;
>  
> -     total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
> +     low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
>  
>       /* crashkernel=Y,low */
> -     ret = parse_crashkernel_low(boot_command_line, total_low_mem, 
> &low_size, &base);
> +     ret = parse_crashkernel_low(boot_command_line, low_mem_limit, 
> &low_size, &base);
>       if (ret) {
>               /*
>                * two parts from kernel/dma/swiotlb.c:
> @@ -443,23 +443,17 @@ static int __init reserve_crashkernel_low(void)
>                       return 0;
>       }
>  
> -     low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
> +     low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, 
> CRASH_ADDR_LOW_MAX);
>       if (!low_base) {
>               pr_err("Cannot reserve %ldMB crashkernel low memory, please try 
> smaller size.\n",
>                      (unsigned long)(low_size >> 20));
>               return -ENOMEM;
>       }
>  
> -     ret = memblock_reserve(low_base, low_size);
> -     if (ret) {
> -             pr_err("%s: Error reserving crashkernel low memblock.\n", 
> __func__);
> -             return ret;
> -     }
> -
> -     pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System 
> low RAM: %ldMB)\n",
> +     pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low 
> RAM limit: %ldMB)\n",
>               (unsigned long)(low_size >> 20),
>               (unsigned long)(low_base >> 20),
> -             (unsigned long)(total_low_mem >> 20));
> +             (unsigned long)(low_mem_limit >> 20));
>  
>       crashk_low_res.start = low_base;
>       crashk_low_res.end   = low_base + low_size - 1;
> @@ -503,13 +497,13 @@ static void __init reserve_crashkernel(void)
>                * unless "crashkernel=size[KMG],high" is specified.
>                */
>               if (!high)
> -                     crash_base = memblock_find_in_range(CRASH_ALIGN,
> -                                             CRASH_ADDR_LOW_MAX,
> -                                             crash_size, CRASH_ALIGN);
> +                     crash_base = memblock_phys_alloc_range(crash_size,
> +                                             CRASH_ALIGN, CRASH_ALIGN,
> +                                             CRASH_ADDR_LOW_MAX);
>               if (!crash_base)
> -                     crash_base = memblock_find_in_range(CRASH_ALIGN,
> -                                             CRASH_ADDR_HIGH_MAX,
> -                                             crash_size, CRASH_ALIGN);
> +                     crash_base = memblock_phys_alloc_range(crash_size,
> +                                             CRASH_ALIGN, CRASH_ALIGN,
> +                                             CRASH_ADDR_HIGH_MAX);
>               if (!crash_base) {
>                       pr_info("crashkernel reservation failed - No suitable 
> area found.\n");
>                       return;
> @@ -517,19 +511,13 @@ static void __init reserve_crashkernel(void)
>       } else {
>               unsigned long long start;
>  
> -             start = memblock_find_in_range(crash_base,
> -                                            crash_base + crash_size,
> -                                            crash_size, 1 << 20);
> +             start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> +                                               crash_base + crash_size);
>               if (start != crash_base) {
>                       pr_info("crashkernel reservation failed - memory is in 
> use.\n");
>                       return;
>               }
>       }
> -     ret = memblock_reserve(crash_base, crash_size);
> -     if (ret) {
> -             pr_err("%s: Error reserving crashkernel memblock.\n", __func__);
> -             return;
> -     }
>  
>       if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
>               memblock_free(crash_base, crash_size);
> -- 
> 2.26.2
> 

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