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SubjectRe: [PATCH v2 3/7] mm,memory_hotplug: Add kernel boot option to enable memmap_on_memory
From
Date
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9bcc460e8bfe..95695483a622 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -42,7 +42,31 @@
> #include "internal.h"
> #include "shuffle.h"
>
> -static bool memmap_on_memory_enabled;
> +/*
> + * memory_hotplug.memmap_on_memory parameter
> + */
> +static bool memmap_on_memory_enabled __ro_after_init;
> +
> +static int memmap_on_memory_show(char *buffer, const struct kernel_param *kp)
> +{
> + return sprintf(buffer, "%s\n",
> + memmap_on_memory_enabled ? "on" : "off");
> +}
> +
> +static __meminit int memmap_on_memory_store(const char *val,
> + const struct kernel_param *kp)
> +{
> + /*
> + * Fail silently in case we cannot enable it due to platform constraints.
> + * User can always check whether it is enabled or not via /sys/module.
> + */
> + if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE))
> + return 0;
> +
> + return param_set_bool(val, kp);
> +}
> +module_param_call(memmap_on_memory, memmap_on_memory_store,
> + memmap_on_memory_show, &memmap_on_memory_enabled, 0400);

Why are other users not allowed to read?

>

Might want to add a MODULE_PARM_DESC().


As we fail silently already, I'd keep it simple and use a

module_param(memmap_on_memory, bool, 0444);

moving the IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) into the
runtime check.


Apart from that LGTM.

--
Thanks,

David / dhildenb

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