linux-kernel - Re: [PATCH v2 5/6] arch: simplify several early memory allocations

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Date:   Mon, 3 Dec 2018 17:29:08 +0100
From:   Sam Ravnborg <sam@...nborg.org>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "David S. Miller" <davem@...emloft.net>,
        Guan Xuetao <gxt@....edu.cn>,
        Greentime Hu <green.hu@...il.com>,
        Jonas Bonn <jonas@...thpole.se>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michal Hocko <mhocko@...e.com>,
        Michal Simek <monstr@...str.eu>,
        Mark Salter <msalter@...hat.com>,
        Paul Mackerras <paulus@...ba.org>,
        Rich Felker <dalias@...c.org>,
        Russell King <linux@...linux.org.uk>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        linux-arm-kernel@...ts.infradead.org, linux-c6x-dev@...ux-c6x.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-sh@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        openrisc@...ts.librecores.org, sparclinux@...r.kernel.org
Subject: Re: [PATCH v2 5/6] arch: simplify several early memory allocations

Hi Mike.

> index c37955d..2a17665 100644
> --- a/arch/sparc/kernel/prom_64.c
> +++ b/arch/sparc/kernel/prom_64.c
> @@ -34,16 +34,13 @@
>  
>  void * __init prom_early_alloc(unsigned long size)
>  {
> -	unsigned long paddr = memblock_phys_alloc(size, SMP_CACHE_BYTES);
> -	void *ret;
> +	void *ret = memblock_alloc(size, SMP_CACHE_BYTES);
>  
> -	if (!paddr) {
> +	if (!ret) {
>  		prom_printf("prom_early_alloc(%lu) failed\n", size);
>  		prom_halt();
>  	}
>  
> -	ret = __va(paddr);
> -	memset(ret, 0, size);
>  	prom_early_allocated += size;
>  
>  	return ret;

memblock_alloc() calls memblock_alloc_try_nid().
And if allocation fails then memblock_alloc_try_nid() calls panic().
So will we ever hit the prom_halt() code?

Do we have a panic() implementation that actually returns?


> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index 3c8aac2..52884f4 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -1089,16 +1089,13 @@ static void __init allocate_node_data(int nid)
>  	struct pglist_data *p;
>  	unsigned long start_pfn, end_pfn;
>  #ifdef CONFIG_NEED_MULTIPLE_NODES
> -	unsigned long paddr;
>  
> -	paddr = memblock_phys_alloc_try_nid(sizeof(struct pglist_data),
> -					    SMP_CACHE_BYTES, nid);
> -	if (!paddr) {
> +	NODE_DATA(nid) = memblock_alloc_node(sizeof(struct pglist_data),
> +					     SMP_CACHE_BYTES, nid);
> +	if (!NODE_DATA(nid)) {
>  		prom_printf("Cannot allocate pglist_data for nid[%d]\n", nid);
>  		prom_halt();
>  	}
> -	NODE_DATA(nid) = __va(paddr);
> -	memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));
>  
>  	NODE_DATA(nid)->node_id = nid;
>  #endif

Same here.

I did not look at the other cases.

	Sam