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Date: Thu, 20 Dec 2012 15:36:57 -0500
From: Sasha Levin <sasha.levin@oracle.com>
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To: David Rientjes <rientjes@google.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Gavin Shan <shangw@linux.vnet.ibm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/sparse: don't check return value of alloc_bootmem
 calls
References: <1356030701-16284-1-git-send-email-sasha.levin@oracle.com> <1356030701-16284-30-git-send-email-sasha.levin@oracle.com> <alpine.DEB.2.00.1212201218590.29839@chino.kir.corp.google.com>
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On 12/20/2012 03:23 PM, David Rientjes wrote:
> On Thu, 20 Dec 2012, Sasha Levin wrote:
> 
>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index 6b5fb76..ae64d6e 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -403,15 +403,13 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
>>  	size = PAGE_ALIGN(size);
>>  	map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
>>  					 PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
>> -	if (map) {
>> -		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
>> -			if (!present_section_nr(pnum))
>> -				continue;
>> -			map_map[pnum] = map;
>> -			map += size;
>> -		}
>> -		return;
>> +	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
>> +		if (!present_section_nr(pnum))
>> +			continue;
>> +		map_map[pnum] = map;
>> +		map += size;
>>  	}
>> +	return;
>>  
>>  	/* fallback */
>>  	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
> 
> That's not true when slab_is_available() and why would you possibly add a 
> return statement right before fallback code in such cases?

So what we really need is to update the documentation of __alloc_bootmem_node, I'll send
a patch that does that instead.

I've dragged the 'return' out of the if(map) condition, I should have removed the fallback
as well and so the return would also be gone, but that's irrelevant now.


Thanks,
Sasha