linux-kernel - Re: [RFC PATCH 1/1] mm/percpu.c: fix memory leakage issue when allocate a odd alignment area

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Message-ID: <57FE0969.8080002@zoho.com>
Date:   Wed, 12 Oct 2016 17:59:05 +0800
From:   zijun_hu <zijun_hu@...o.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org, zijun_hu@....com,
        tj@...nel.org, akpm@...ux-foundation.org, cl@...ux.com
Subject: Re: [RFC PATCH 1/1] mm/percpu.c: fix memory leakage issue when
 allocate a odd alignment area

On 10/12/2016 05:54 PM, Michal Hocko wrote:
> On Wed 12-10-16 16:44:31, zijun_hu wrote:
>> On 10/12/2016 04:25 PM, Michal Hocko wrote:
>>> On Wed 12-10-16 15:24:33, zijun_hu wrote:
> [...]
>>>> i found the following code segments in mm/vmalloc.c
>>>> static struct vmap_area *alloc_vmap_area(unsigned long size,
>>>>                                 unsigned long align,
>>>>                                 unsigned long vstart, unsigned long vend,
>>>>                                 int node, gfp_t gfp_mask)
>>>> {
>>>> ...
>>>>
>>>>         BUG_ON(!size);
>>>>         BUG_ON(offset_in_page(size));
>>>>         BUG_ON(!is_power_of_2(align));
>>>
>>> See a recent Linus rant about BUG_ONs. These BUG_ONs are quite old and
>>> from a quick look they are even unnecessary. So rather than adding more
>>> of those, I think removing those that are not needed is much more
>>> preferred.
>>>
>> i notice that, and the above code segments is used to illustrate that
>> input parameter checking is necessary sometimes
> 
> Why do you think it is necessary here?
> 
i am sorry for reply late
i don't know whether it is necessary
i just find there are so many sanity checkup in current internal interfaces