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b=QqjCuJgfjT1BWsndH125Lho+YjEk1oOumDbtnuy9/lGIQHFI/92h9SK+lz/3+9YQJSYh/1 ZPhC+rRzQr5qcJjSuGWdjfbCd+gfPXLgHjS7wqgtESoRI23jCb7Vd1fr6q0xPeItTGrWU3 WIJK8oOxV/wHkUEtUWIESj8RqC1AXpc= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 2B2A32C142; Tue, 4 Apr 2023 12:03:47 +0000 (UTC) Date: Tue, 4 Apr 2023 14:03:47 +0200 From: Petr Mladek To: Jaewon Kim Cc: David Laight , 'Jaewon Kim' , "senozhatsky@chromium.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , GyeongHwan Hong Subject: Re: [RFC] vsprintf: compile error on %09pK Message-ID: References: <694722c9409b43808cfbc1fc9e495016@AcuMS.aculab.com> <20230403104617epcms1p383bacbca705c0d7e4fffca6833050e42@epcms1p3> <20230404101201epcms1p615a6365e64fc6e0a0fa203d41404940c@epcms1p6> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230404101201epcms1p615a6365e64fc6e0a0fa203d41404940c@epcms1p6> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A0D51180003 X-Stat-Signature: ic73ia3w9uha4ojyzxpxykztpckwmzxt X-Rspam-User: X-HE-Tag: 1680609830-949773 X-HE-Meta: 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 wAiHBFfy bWri2s0J6fnPPuFG95xai31ShWThI9wbOPtXBrRMVk3Qk42rX0eCj8rj6eqYpIKgYB+4dRYjCLI+OTNkt9C0bOMhIbdga9F+CwCOvK08YTcZOICeJSbwZyy5T0HpWysOAysOnzYemtWiJ0+JKs7WhPwj5JvWKMGKNOy079kd0U7VtTuraB+N8RStBnnhY/f4/cT3QrrRzQt/PAbTYofcA6VZntnRxjK1HiOinvE1/Aev0amHgE91fxQDxjPflrVuc35IuRFKhjwyxsvBaBkN5PB3PZA== 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 2023-04-04 19:12:01, Jaewon Kim wrote: > >From: Jaewon Kim > >> Sent: 03 April 2023 15:40 > >... > >> I wanted to print phys_addr_t type value only when kptr_restrict sysctl is > >> allowed. So I thought I could use %pK for that purpose. And the physical > >> address is not that long. I wanted to make that length short like 9 hex. > > > >Isn't that is the wrong format for physical addresses anyway? > >They can be larger than virtual ones (eg x86 with PAE). > > Yeah, correct. I just used %pK to hide physical address, I thought it could be > leak in security perspective. Could you give me advice how I can hide the > address by default and look the address if kptr_restrict allow it? Could you please send a patch that would show what value you want to print? The initial mail mentioned converting %09lx to %09pK in some driver. Then it included a warning when compiling from mm/page_alloc.o Honestly, I think that you could just use %pK or %p. IMHO, it does not make sense to optimize it for the length. Anyway, there is still the question if the address is really worth printing. Will it really help to locate a potential problem? Best Regards, Petr