Re: [PATCH] mm/memblock: Add memblock_alloc_or_panic interface

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

On Fri, 20 Dec 2024 17:26:38 +0800 Guo Weikang <guoweikang.kernel@xxxxxxxxx> 
wrote:

> Before SLUB initialization, various subsystems used memblock_alloc to
> allocate memory. In most cases, when memory allocation fails, an immediate
> panic is required. To simplify this behavior and reduce repetitive checks,
> introduce `memblock_alloc_or_panic`. This function ensures that memory
> allocation failures result in a panic automatically, improving code
> readability and consistency across subsystems that require this behavior.
> 

Seems nice.

> ...
>
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -417,6 +417,19 @@ static __always_inline void *memblock_alloc(phys_addr_t 
> size, phys_addr_t align)
>                                     MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE);
>  }
>  
> +static __always_inline void *memblock_alloc_or_panic(phys_addr_t size, 
> phys_addr_t align)

We lost the printing of the function name, but it's easy to retain with
something like

#define memblock_alloc_or_panic(size, align)    \
                __memblock_alloc_or_panic(size, align, __func__)

> +{
> +     void *addr = memblock_alloc(size, align);
> +
> +     if (unlikely(!addr))
> +#ifdef CONFIG_PHYS_ADDR_T_64BIT
> +             panic("%s: Failed to allocate %llu bytes\n", __func__, size);

Won't this always print "memblock_alloc_or_panic: Failed ..."?  Not
very useful.

> +#else
> +             panic("%s: Failed to allocate %u bytes\n", __func__, size);
> +#endif

We can avoid the ifdef with printk's "%pap"?

> +     return addr;
> +}