Date: Wed, 12 Oct 2016 11:54:39 +0200
From: Michal Hocko <mhocko@kernel.org>
To: zijun_hu <zijun_hu@zoho.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, zijun_hu@htc.com,
        tj@kernel.org, akpm@linux-foundation.org, cl@linux.com
Subject: Re: [RFC PATCH 1/1] mm/percpu.c: fix memory leakage issue when
 allocate a odd alignment area
Message-ID: <20161012095439.GI17128@dhcp22.suse.cz>
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 <20161012065332.GA9504@dhcp22.suse.cz>
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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?

-- 
Michal Hocko
SUSE Labs