linux-kernel - Re: [PATCH 1/1] mm: sysctl: add panic_on_inconsistent

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Message-ID: <202001301128.1CBD1BA52@keescook>
Date:   Thu, 30 Jan 2020 11:28:45 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Vlastimil Babka <vbabka@...e.cz>
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 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?

-- 
Kees Cook