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

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Date:   Thu, 1 Feb 2018 23:22:55 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Matthew Wilcox <willy@...radead.org>
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 02/01/2018 10:57 PM, Matthew Wilcox wrote:
> On Thu, Feb 01, 2018 at 07:33:49PM +0300, Andrey Ryabinin wrote:
>> +	case MEM_OFFLINE: {
>> +		struct vm_struct *vm;
>> +
>> +		/*
>> +		 * Only hot-added memory have vm_area. Freeing shadow
>> +		 * mapped during boot would be tricky, so we'll just
>> +		 * have to keep it.
>> +		 */
>> +		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.