Re: [PATCH v7] mm/memblock: Add memblock_alloc_or_panic interface

[Alexander Gordeev <agordeev@linux.ibm.com>]

On Sun, Dec 22, 2024 at 07:15:37PM +0800, Guo Weikang wrote:

Hi Guo,

> 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.

I believe, you also want to make similar function against memblock_alloc_low().

Please, find s390 comments below.

...

> diff --git a/arch/s390/kernel/numa.c b/arch/s390/kernel/numa.c
> index ddc1448ea2e1..a33e20f73330 100644
> --- a/arch/s390/kernel/numa.c
> +++ b/arch/s390/kernel/numa.c
> @@ -22,10 +22,7 @@ void __init numa_setup(void)
>  	node_set(0, node_possible_map);
>  	node_set_online(0);
>  	for (nid = 0; nid < MAX_NUMNODES; nid++) {
> -		NODE_DATA(nid) = memblock_alloc(sizeof(pg_data_t), 8);
> -		if (!NODE_DATA(nid))
> -			panic("%s: Failed to allocate %zu bytes align=0x%x\n",
> -			      __func__, sizeof(pg_data_t), 8);
> +		NODE_DATA(nid) = memblock_alloc_or_panic(sizeof(pg_data_t), 8);
>  	}

Please, also remove the cycle body brackets.

>  	NODE_DATA(0)->node_spanned_pages = memblock_end_of_DRAM() >> PAGE_SHIFT;
>  	NODE_DATA(0)->node_id = 0;
> diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
> index 0ce550faf073..1298f0860733 100644
> --- a/arch/s390/kernel/setup.c
> +++ b/arch/s390/kernel/setup.c
> @@ -376,11 +376,7 @@ static unsigned long __init stack_alloc_early(void)
>  {
>  	unsigned long stack;
>  
> -	stack = (unsigned long)memblock_alloc(THREAD_SIZE, THREAD_SIZE);
> -	if (!stack) {
> -		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
> -		      __func__, THREAD_SIZE, THREAD_SIZE);
> -	}
> +	stack = (unsigned long)memblock_alloc_or_panic(THREAD_SIZE, THREAD_SIZE);
>  	return stack;
>  }
>  
> @@ -504,10 +500,7 @@ static void __init setup_resources(void)
>  	bss_resource.end = __pa_symbol(__bss_stop) - 1;
>  
>  	for_each_mem_range(i, &start, &end) {
> -		res = memblock_alloc(sizeof(*res), 8);
> -		if (!res)
> -			panic("%s: Failed to allocate %zu bytes align=0x%x\n",
> -			      __func__, sizeof(*res), 8);
> +		res = memblock_alloc_or_panic(sizeof(*res), 8);
>  		res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
>  
>  		res->name = "System RAM";
> @@ -526,10 +519,7 @@ static void __init setup_resources(void)
>  			    std_res->start > res->end)
>  				continue;
>  			if (std_res->end > res->end) {
> -				sub_res = memblock_alloc(sizeof(*sub_res), 8);
> -				if (!sub_res)
> -					panic("%s: Failed to allocate %zu bytes align=0x%x\n",
> -					      __func__, sizeof(*sub_res), 8);
> +				sub_res = memblock_alloc_or_panic(sizeof(*sub_res), 8);
>  				*sub_res = *std_res;
>  				sub_res->end = res->end;
>  				std_res->start = res->end + 1;
> @@ -816,9 +806,7 @@ static void __init setup_randomness(void)
>  {
>  	struct sysinfo_3_2_2 *vmms;
>  
> -	vmms = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> -	if (!vmms)
> -		panic("Failed to allocate memory for sysinfo structure\n");
> +	vmms = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
>  	if (stsi(vmms, 3, 2, 2) == 0 && vmms->count)
>  		add_device_randomness(&vmms->vm, sizeof(vmms->vm[0]) * vmms->count);
>  	memblock_free(vmms, PAGE_SIZE);
> diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
> index 822d8e6f8717..d77aaefb59bd 100644
> --- a/arch/s390/kernel/smp.c
> +++ b/arch/s390/kernel/smp.c
> @@ -611,9 +611,9 @@ void __init smp_save_dump_ipl_cpu(void)
>  	if (!dump_available())
>  		return;
>  	sa = save_area_alloc(true);
> -	regs = memblock_alloc(512, 8);
> -	if (!sa || !regs)
> +	if (!sa)
>  		panic("could not allocate memory for boot CPU save area\n");

Please, replace memblock_alloc() with memblock_alloc_or_panic() in
save_area_alloc() and remove the error handling here and also in
smp_save_dump_secondary_cpus().

> +	regs = memblock_alloc_or_panic(512, 8);
>  	copy_oldmem_kernel(regs, __LC_FPREGS_SAVE_AREA, 512);
>  	save_area_add_regs(sa, regs);
>  	memblock_free(regs, 512);
> @@ -792,10 +792,7 @@ void __init smp_detect_cpus(void)
>  	u16 address;
>  
>  	/* Get CPU information */
> -	info = memblock_alloc(sizeof(*info), 8);
> -	if (!info)
> -		panic("%s: Failed to allocate %zu bytes align=0x%x\n",
> -		      __func__, sizeof(*info), 8);
> +	info = memblock_alloc_or_panic(sizeof(*info), 8);
>  	smp_get_core_info(info, 1);
>  	/* Find boot CPU type */
>  	if (sclp.has_core_type) {
> diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
> index 0fd56a1cadbd..cf5ee6032c0b 100644
> --- a/arch/s390/kernel/topology.c
> +++ b/arch/s390/kernel/topology.c
> @@ -548,10 +548,7 @@ static void __init alloc_masks(struct sysinfo_15_1_x *info,
>  		nr_masks *= info->mag[TOPOLOGY_NR_MAG - offset - 1 - i];
>  	nr_masks = max(nr_masks, 1);
>  	for (i = 0; i < nr_masks; i++) {
> -		mask->next = memblock_alloc(sizeof(*mask->next), 8);
> -		if (!mask->next)
> -			panic("%s: Failed to allocate %zu bytes align=0x%x\n",
> -			      __func__, sizeof(*mask->next), 8);
> +		mask->next = memblock_alloc_or_panic(sizeof(*mask->next), 8);
>  		mask = mask->next;
>  	}
>  }
> @@ -569,10 +566,7 @@ void __init topology_init_early(void)
>  	}
>  	if (!MACHINE_HAS_TOPOLOGY)
>  		goto out;
> -	tl_info = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> -	if (!tl_info)
> -		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
> -		      __func__, PAGE_SIZE, PAGE_SIZE);
> +	tl_info = memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
>  	info = tl_info;
>  	store_topology(info);
>  	pr_info("The CPU configuration topology of the machine is: %d %d %d %d %d %d / %d\n",

Thanks!