linux-kernel - Re: [PATCH] kasan: avoid overflowing quarantine size on low memory systems

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Date:	Tue, 2 Aug 2016 13:23:43 +0300
From:	Andrey Ryabinin <aryabinin@...tuozzo.com>
To:	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>
CC:	Kostya Serebryany <kcc@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Christoph Lameter <cl@...ux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Joonsoo Kim <js1304@...il.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Kuthonuzo Luruo <kuthonuzo.luruo@....com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH] kasan: avoid overflowing quarantine size on low memory
 systems



On 08/02/2016 01:07 PM, Alexander Potapenko wrote:
> On Tue, Aug 2, 2016 at 12:05 PM, Dmitry Vyukov <dvyukov@...gle.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.