On 29.01.20 19:39, Qian Cai wrote: > > >> On Jan 29, 2020, at 1:08 PM, Grzegorz Halat <ghalat@xxxxxxxxxx> 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). >> >> Another use case of this sysctl may be in security-wise environments, >> it may be more desired to crash machine than continue to run with >> potentially damaged data structures. > > It is annoying that I have to repeat my feedback, but I don’t know why > admins want to enable this by allowing normal users to crash the systems > more easily through recoverable MM bugs where I am sure we have plenty. > How does that improve the security? There are cases where data corruption is a no-go, while "one node going down" is acceptable. And then there is also the case for payed service providers that often need a dump at the time of the problem to understand rare issues. So I DO see value in such a thing. We should just piggy-back on panic_on_warn I guess.
