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bh=X+5emsm5/XcM0QeOriAGVbzKqML6KnpuYnqauTGrAr8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=PVCaji7MVpWuFJdo47N9kdRSDsKscdneyyrEGnaFAcoEtPlG/TQvDttw4zVBPcm1H AtENa8f86w1D1W26qU9Tqd7UXzDCbL1Sn6PJ5AjLx8ahCE6+FG6NyJSjq2Cwu8EknG u5JOA/Az/AO8ixvecHnhIObLUgthorFGPFqpgYmg= Date: Tue, 18 Apr 2023 12:33:38 -0700 From: Andrew Morton To: Matthew Wilcox Cc: "zhaoyang.huang" , Minchan Kim , Joonsoo Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhaoyang Huang , ke.wang@unisoc.com Subject: Re: [PATCH] mm: fix printk format within cma Message-Id: <20230418123338.3b85a013cf6ce1fcb3677ae2@linux-foundation.org> In-Reply-To: References: <1681788789-19679-1-git-send-email-zhaoyang.huang@unisoc.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: f1mmo6457ft9ig4khxzhbjpwrcc6tgpn X-Rspamd-Queue-Id: 67DBA80018 X-HE-Tag: 1681846421-934495 X-HE-Meta: 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 qvOxhg2l qlEeqPGJdIha27gW0hUAe8b9FiQr+PQUlDF9GwDFVaxM5YhoHrBWXAS5x9o9nFvqZWsZtK+iUBP1ffwyH58/IEnfvw+Ra6Lfx5ucOElcBNAg96oU3xQXAqYNazc/++AQRjCmJLCHbIeA4mhXKfOAaIZ3CUPtG+FPBgXGjAVeZHLVmDChka/I8X/Ye8WXWUSpoCdWkCFKw2oNNbJyyu80XuVCAouryPTEy10vlk56StUgPATZYGnuQMtCWy18ucH71IDCVeR8yBuJLAxEGyjc9WRTfwxOoE8SVQ+TIYCYsajTm0hwWItUcs1sQrgi7rzzU5a7+bUTFrN2oxaottrLu3pHx+jG9ebF4TnumpqC37ALMz6QR5YRL59ECZFQhN2rFx9iJvDRNP8cWKdf5e98lnKgXrQ== 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, 18 Apr 2023 04:38:24 +0100 Matthew Wilcox wrote: > On Tue, Apr 18, 2023 at 11:33:09AM +0800, zhaoyang.huang wrote: > > cma and page pointer printed via %p are hash value which make debug to be hard. > > change them to %px. > > Why does printing the page pointer make any sense at all? Surely the > PFN makes much more sense. I suppose one could correlate a particular hashed pointer with other debug output, see "ah, that's the same page". In which case one doesn't really care whether or not the address is hashed - it's just a cookie. This sounds thin. I doubt if a lot of thought went into the printk. If the page pointer isn't useful then how about we simply remove it from the message?