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Date: Tue, 13 Mar 2018 19:35:44 +0100 (CET)
From: Julia Lawall <julia.lawall@lip6.fr>
Subject: Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc_struct
In-Reply-To: <20180313183220.GA21538@bombadil.infradead.org>
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References: <20180214182618.14627-1-willy@infradead.org> <20180214182618.14627-3-willy@infradead.org> <CAGXu5jL9hqQGe672CmvFwqNbtTr=qu7WRwHuS4Vy7o5sX_UTgg@mail.gmail.com> <alpine.DEB.2.20.1803072212160.2814@hadrien> <20180308025812.GA9082@bombadil.infradead.org>
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To: Matthew Wilcox <willy@infradead.org>
Cc: Kees Cook <keescook@chromium.org>, Andrew Morton <akpm@linux-foundation.org>, Matthew Wilcox <mawilcox@microsoft.com>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Kernel Hardening <kernel-hardening@lists.openwall.com>, cocci@systeme.lip6.fr, Himanshu Jha <himanshujha199640@gmail.com>



On Tue, 13 Mar 2018, Matthew Wilcox wrote:

> On Tue, Mar 13, 2018 at 06:19:51PM +0100, Julia Lawall wrote:
> > On Thu, 8 Mar 2018, Matthew Wilcox wrote:
> > > On Thu, Mar 08, 2018 at 07:24:47AM +0100, Julia Lawall wrote:
> > > > Thanks.  So it's OK to replace kmalloc and kzalloc, even though they
> > > > didn't previously consider vmalloc and even though kmalloc doesn't zero?
> > >
> > > We'll also need to replace the corresponding places where those structs
> > > are freed with kvfree().  Can coccinelle handle that too?
> >
> > Is the use of vmalloc a necessary part of the design?  Or could there be a
> > non vmalloc versions for call sites that are already ok with that?
>
> We can also add kmalloc_struct() along with kmalloc_ab_c that won't fall
> back to vmalloc but just return NULL.

It could be safer than being sure to find all of the relevant kfrees.

julia