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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id r9sm8228895pfg.2.2020.03.31.11.26.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2020 11:26:52 -0700 (PDT) Date: Tue, 31 Mar 2020 11:26:51 -0700 From: Kees Cook To: Michal Hocko Cc: Vlastimil Babka , Luis Chamberlain , Iurii Zaikin , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-mm@kvack.org, Ivan Teterevkov , David Rientjes , Matthew Wilcox , "Eric W . Biederman" , "Guilherme G . Piccoli" , Alexey Dobriyan , Thomas Gleixner , Greg Kroah-Hartman , Christian Brauner Subject: Re: [PATCH 1/3] kernel/sysctl: support setting sysctl parameters from kernel command line Message-ID: <202003311125.939F851A6@keescook> References: <20200330115535.3215-1-vbabka@suse.cz> <20200330115535.3215-2-vbabka@suse.cz> <20200330224422.GX11244@42.do-not-panic.com> <8146e3d0-89c3-7f79-f786-084c58282c85@suse.cz> <20200331074836.GB30449@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200331074836.GB30449@dhcp22.suse.cz> 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 Tue, Mar 31, 2020 at 09:48:36AM +0200, Michal Hocko wrote: > On Tue 31-03-20 09:42:46, Vlastimil Babka wrote: > [...] > > > Should we not do this, we'll have to live with the consequences of > > > supporting the full swoop of sysctls are boot params, whatever > > > consequences those may be. > > > > Of course when the first user tries to set some particular sysctl as boot param > > and finds and reports it doesn't work as intended, then it can be fixed or > > blacklisted and it can't break anyone else? > > Absolutely agreed. I would be really careful to not overengineer this > whole thing. Right -- this is supposed to be _simple_, and I think that's the primary benefit here. If we encounter problems we can fix those cases. The careful place, I think, needs to be with converting existing boot params to be aliases. That's when timing considerations need to be taken into account carefully. -- Kees Cook