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Subject: Re: [PATCH] kasan: avoid overflowing quarantine size on low memory
 systems
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From: Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <57A074AF.3040505@virtuozzo.com>
Date: Tue, 2 Aug 2016 13:23:43 +0300
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To: Alexander Potapenko <glider@google.com>, Dmitry Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>, Andrey Konovalov <adech.fo@gmail.com>, Christoph Lameter <cl@linux.com>, Andrew Morton <akpm@linux-foundation.org>, Steven Rostedt <rostedt@goodmis.org>, Joonsoo Kim <js1304@gmail.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>, kasan-dev <kasan-dev@googlegroups.com>, LKML <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>



On 08/02/2016 01:07 PM, Alexander Potapenko wrote:
> On Tue, Aug 2, 2016 at 12:05 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> On Tue, Aug 2, 2016 at 12:00 PM, Andrey Ryabinin
>>>
>>> Why WARN? I'd suggest pr_warn_once();
>>
>>
>> I would suggest to just do something useful. Setting quarantine
>> new_quarantine_size to 0 looks fine.
>> What would user do with this warning? Number of CPUs and amount of
>> memory are generally fixed. Why is it an issue for end user at all? We
>> still have some quarantine per-cpu. A WARNING means a [non-critical]
>> kernel bug. E.g. syzkaller will catch each and every boot of such
>> system as a bug.
> How about printk_once then?
> Silently setting the quarantine size to zero may puzzle the user.
>

Nope, user will not notice anything. So keeping it silent would be better.
Plus it's very unlikely that this will ever happen in real life.

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