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Date:   Wed, 25 Jan 2017 14:09:01 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Ben Skeggs <bskeggs@...hat.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Santosh Raspatur <santosh@...lsio.com>,
        Hariprasad S <hariprasad@...lsio.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Yishai Hadas <yishaih@...lanox.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        David Sterba <dsterba@...e.com>,
        "Yan, Zheng" <zyan@...hat.com>, Ilya Dryomov <idryomov@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH 5/6] treewide: use kv[mz]alloc* rather than opencoded
 variants

On Wed 25-01-17 12:15:59, Vlastimil Babka wrote:
> On 01/24/2017 04:00 PM, Michal Hocko wrote:
> > > > Well, I am not opposed to kvmalloc_array but I would argue that this
> > > > conversion cannot introduce new overflow issues. The code would have
> > > > to be broken already because even though kmalloc_array checks for the
> > > > overflow but vmalloc fallback doesn't...
> > > 
> > > Yeah I agree, but if some of the places were really wrong, after the
> > > conversion we won't see them anymore.
> > > 
> > > > If there is a general interest for this API I can add it.
> > > 
> > > I think it would be better, yes.
> > 
> > OK, fair enough. I will fold the following into the original patch. I
> > was little bit reluctant to create kvcalloc so I've made the original
> > callers more talkative and added | __GFP_ZERO.
> 
> Fair enough,
> 
> > To be honest I do not
> > really like how kcalloc...
> 
> how kcalloc what?

how kcalloc hides the GFP_ZERO and the name doesn't reflect that.
 
> [...]
> > diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
> > index cdc55d5ee4ad..eca16612b1ae 100644
> > --- a/net/netfilter/x_tables.c
> > +++ b/net/netfilter/x_tables.c
> > @@ -712,10 +712,7 @@ EXPORT_SYMBOL(xt_check_entry_offsets);
> >   */
> >  unsigned int *xt_alloc_entry_offsets(unsigned int size)
> >  {
> > -	if (size < (SIZE_MAX / sizeof(unsigned int)))
> > -		return kvzalloc(size * sizeof(unsigned int), GFP_KERNEL);
> > -
> > -	return NULL;
> > +	return kvmalloc_array(size * sizeof(unsigned int), GFP_KERNEL | __GFP_ZERO);
> 
> This one wouldn't compile.

fixed, thanks!

-- 
Michal Hocko
SUSE Labs

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