linux-kernel - Re: [PATCH] mm/kasan: Don't vfree() nonexistent vm

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Date:   Fri, 2 Feb 2018 09:20:27 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Paul Menzel <pmenzel+linux-kasan-dev@...gen.mpg.de>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] mm/kasan: Don't vfree() nonexistent vm_area.

On Thu, Feb 01, 2018 at 11:22:55PM +0300, Andrey Ryabinin wrote:
> >> +		vm = find_vm_area((void *)shadow_start);
> >> +		if (vm)
> >> +			vfree((void *)shadow_start);
> >> +	}
> > 
> > This looks like a complicated way to spell 'is_vmalloc_addr' ...
> > 
> 
> It's not. shadow_start is never vmalloc address.

I'm confused.  How can you call vfree() on something that isn't a vmalloc
address?