linux-kernel - Re: [PATCH v2, part3 02/12] mm/ARM64: kill poison_init

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Message-ID: <51474D2E.7060709@gmail.com>
Date:	Tue, 19 Mar 2013 01:21:50 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Will Deacon <will.deacon@....com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Minchan Kim <minchan@...nel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Michal Hocko <mhocko@...e.cz>,
	Jianguo Wu <wujianguo@...wei.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2, part3 02/12] mm/ARM64: kill poison_init_mem()

On 03/18/2013 05:46 AM, Will Deacon wrote:
> On Sat, Mar 16, 2013 at 05:03:23PM +0000, Jiang Liu wrote:
>> Use free_reserved_area() to kill poison_init_mem() on ARM64.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Will Deacon <will.deacon@....com>
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> ---
>>  arch/arm64/mm/init.c |   17 +++--------------
>>  1 file changed, 3 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index e58dd7f..b87bdb8 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -197,14 +197,6 @@ void __init bootmem_init(void)
>>  	max_pfn = max_low_pfn = max;
>>  }
>>  
>> -/*
>> - * Poison init memory with an undefined instruction (0x0).
>> - */
>> -static inline void poison_init_mem(void *s, size_t count)
>> -{
>> -	memset(s, 0, count);
>> -}
>> -
>>  #ifndef CONFIG_SPARSEMEM_VMEMMAP
>>  static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
>>  {
>> @@ -386,8 +378,7 @@ void __init mem_init(void)
>>  
>>  void free_initmem(void)
>>  {
>> -	poison_init_mem(__init_begin, __init_end - __init_begin);
>> -	 free_initmem_default(-1);
>> +	free_initmem_default(0);
> 
> This change looks unrelated to $subject. We should probably just poison with
> 0 from the outset, when free_initmem_default is introduced.
Hi Will,
	As you have suggested, this patch should be merged into patchset which
introduces free_initmem_default(). I have a plan to merge it in v3, but the v2
patchset has been merged into -mm tree, so I generated another patch against the
mm tree.
	free_initmem_default(-1) doesn't poison the freed memory and 
free_initmem_default(0) poisons the freed memory with 0, so it's needed to
kill poison_init_mem().

regards!
Gerry

> 
> Will
> --
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