linux-kernel - Re: [PATCH] mm/memcontrol.c: add memory allocation result check

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Message-ID: <CACygaLCupPNRMWUpRe3WSCHWtAFH3MYKzppbjaX3As6EKKnVQQ@mail.gmail.com>
Date:	Mon, 30 May 2016 17:28:40 +0800
From:	Wenwei Tao <ww.tao0320@...il.com>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	Wenwei Tao <wwtao0320@....com>, hannes@...xchg.org,
	vdavydov@...tuozzo.com, cgroups@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/memcontrol.c: add memory allocation result check

I think explicit BUG_ON may make the debug easier, since it can point
out the wrong line.

2016-05-30 16:53 GMT+08:00 Michal Hocko <mhocko@...nel.org>:
> On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
>> From: Wenwei Tao <ww.tao0320@...il.com>
>>
>> The mem_cgroup_tree_per_node allocation might fail,
>> check that before continue the memcg init. Since it
>> is in the init phase, trigger the panic if that failure
>> happens.
>
> We would blow up in the very same function so what is the point of the
> explicit BUG_ON?
>
>> Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
>> ---
>>  mm/memcontrol.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 925b431..6385c62 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
>>
>>               rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
>>                                   node_online(node) ? node : NUMA_NO_NODE);
>> +             BUG_ON(!rtpn);
>>
>>               for (zone = 0; zone < MAX_NR_ZONES; zone++) {
>>                       struct mem_cgroup_tree_per_zone *rtpz;
>> --
>> 1.8.3.1
>>
>>
>> --
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>
> --
> Michal Hocko
> SUSE Labs