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Date:   Fri, 2 Feb 2018 09:20:27 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Paul Menzel <pmenzel+linux-kasan-dev@molgen.mpg.de>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org
Subject: Re: [PATCH] mm/kasan: Don't vfree() nonexistent vm_area.
Message-ID: <20180202172027.GB16840@bombadil.infradead.org>
References: <12c9e499-9c11-d248-6a3f-14ec8c4e07f1@molgen.mpg.de>
 <20180201163349.8700-1-aryabinin@virtuozzo.com>
 <20180201195757.GC20742@bombadil.infradead.org>
 <e1cf8e8e-4cc4-ff4f-92e1-f6fcf373c67f@virtuozzo.com>
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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?