On 04/07/23 at 10:24am, Baoquan He wrote:
......
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 66e70ca47680..307263c01292 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -69,6 +69,7 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
>
> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit
> #define CRASH_ADDR_HIGH_MAX (PHYS_MASK + 1)
> +#define CRASH_HIGH_SEARCH_BASE SZ_4G
>
> #define DEFAULT_CRASH_KERNEL_LOW_SIZE (128UL << 20)
>
> @@ -101,12 +102,13 @@ static int __init reserve_crashkernel_low(unsigned long
> long low_size)
> */
> static void __init reserve_crashkernel(void)
> {
> - unsigned long long crash_base, crash_size;
> - unsigned long long crash_low_size = 0;
> + unsigned long long crash_base, crash_size, search_base;
> unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
> + unsigned long long crash_low_size = 0;
> char *cmdline = boot_command_line;
> - int ret;
> bool fixed_base = false;
> + bool high = false;
> + int ret;
>
> if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> return;
> @@ -129,7 +131,9 @@ static void __init reserve_crashkernel(void)
> else if (ret)
> return;
>
> + search_base = CRASH_HIGH_SEARCH_BASE;
Here, I am hesitant if a conditional check is needed as below. On
special system where both CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32
are disabled, there's only low memory, means its arm64_dma_phys_limit
equals to (PHYS_MASK + 1). In this case, whatever the crashkernel= is,
it can search the whole system memory for available crashkernel region.
Maybe it's fine since it's not big deal, the memory regoin can be found
anyway.
crash_max = CRASH_ADDR_HIGH_MAX;
if (crash_max != CRASH_ADDR_LOW_MAX)
search_base = CRASH_HIGH_SEARCH_BASE;
> + high = true;
> } else if (ret || !crash_size) {
> /* The specified value is invalid */
> return;
> @@ -140,31 +144,51 @@ static void __init reserve_crashkernel(void)
> /* User specifies base address explicitly. */
> if (crash_base) {
> fixed_base = true;
> + search_base = crash_base;
> crash_max = crash_base + crash_size;
> }
>
> retry:
> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> - crash_base, crash_max);
> + search_base, crash_max);
> if (!crash_base) {
> /*
> - * If the first attempt was for low memory, fall back to
> - * high memory, the minimum required low memory will be
> - * reserved later.
> + * For crashkernel=size[KMG]@offset[KMG], print out failure
> + * message if can't reserve the specified region.
> */
> - if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) {
> + if (fixed_base) {
> + pr_warn("crashkernel reservation failed - memory is in
> use.\n");
> + return;
> + }
> +
> + /*
> + * For crashkernel=size[KMG], if the first attempt was for
> + * low memory, fall back to high memory, the minimum required
> + * low memory will be reserved later.
> + */
> + if (!high && crash_max == CRASH_ADDR_LOW_MAX) {
> crash_max = CRASH_ADDR_HIGH_MAX;
> + search_base = CRASH_ADDR_LOW_MAX;
> crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> goto retry;
> }
>
> + /*
> + * For crashkernel=size[KMG],high, if the first attempt was
> + * for high memory, fall back to low memory.
> + */
> + if (high && crash_max == CRASH_ADDR_HIGH_MAX) {
> + crash_max = CRASH_ADDR_LOW_MAX;
> + search_base = 0;
> + goto retry;
> + }
> pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> crash_size);
> return;
> }
>
> - if ((crash_base > CRASH_ADDR_LOW_MAX - crash_low_size) &&
> - crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> + if ((crash_base >= CRASH_ADDR_LOW_MAX) && crash_low_size &&
> + reserve_crashkernel_low(crash_low_size)) {
> memblock_phys_free(crash_base, crash_size);
> return;
> }
> --
> 2.34.1
>
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