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Message-ID: <1cb86d36-7620-be11-7833-0b3bab3c5c1f@suse.cz>
Date: Mon, 3 Feb 2020 13:19:29 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Kees Cook <keescook@...omium.org>
Cc: Grzegorz Halat <ghalat@...hat.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
linux-doc@...r.kernel.org, ssaner@...hat.com, atomlin@...hat.com,
oleksandr@...hat.com, vbendel@...hat.com, kirill@...temov.name,
khlebnikov@...dex-team.ru, borntraeger@...ibm.com,
Andrew Morton <akpm@...ux-foundation.org>,
Iurii Zaikin <yzaikin@...gle.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Jonathan Corbet <corbet@....net>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Qian Cai <cai@....pw>
Subject: Re: [PATCH 1/1] mm: sysctl: add panic_on_inconsistent_mm sysctl
On 1/30/20 8:28 PM, Kees Cook wrote:
> On Thu, Jan 30, 2020 at 03:44:50PM +0100, Vlastimil Babka wrote:
>> On 1/29/20 7:08 PM, Grzegorz Halat wrote:
>>> Memory management subsystem performs various checks at runtime,
>>> if an inconsistency is detected then such event is being logged and kernel
>>> continues to run. While debugging such problems it is helpful to collect
>>> memory dump as early as possible. Currently, there is no easy way to panic
>>> kernel when such error is detected.
>>>
>>> It was proposed[1] to panic the kernel if panic_on_oops is set but this
>>> approach was not accepted. One of alternative proposals was introduction of
>>> a new sysctl.
>>>
>>> Add a new sysctl - panic_on_inconsistent_mm. If the sysctl is set then the
>>> kernel will be crashed when an inconsistency is detected by memory
>>> management. This currently means panic when bad page or bad PTE
>>> is detected(this may be extended to other places in MM).
>>
>> I wonder, should enabling the sysctl also effectively convert VM_WARN...
>> to VM_BUG... ?
>
> There is already panic_on_warn sysctl... wouldn't that be sufficient?
True, forgot about it. Thanks.
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