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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id e19sm7197844pgn.86.2020.01.30.11.28.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jan 2020 11:28:46 -0800 (PST) Date: Thu, 30 Jan 2020 11:28:45 -0800 From: Kees Cook To: Vlastimil Babka Cc: Grzegorz Halat , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, ssaner@redhat.com, atomlin@redhat.com, oleksandr@redhat.com, vbendel@redhat.com, kirill@shutemov.name, khlebnikov@yandex-team.ru, borntraeger@de.ibm.com, Andrew Morton , Iurii Zaikin , Luis Chamberlain , Jonathan Corbet , Tetsuo Handa , Qian Cai Subject: Re: [PATCH 1/1] mm: sysctl: add panic_on_inconsistent_mm sysctl Message-ID: <202001301128.1CBD1BA52@keescook> References: <20200129180851.551109-1-ghalat@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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