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[140.211.169.12]) by mx.google.com with ESMTPS id n14si5230204plp.257.2019.02.12.13.46.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Feb 2019 13:46:23 -0800 (PST) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 4C530E67A; Tue, 12 Feb 2019 21:46:23 +0000 (UTC) Date: Tue, 12 Feb 2019 13:46:22 -0800 From: Andrew Morton To: Michal Hocko Cc: keith.busch@intel.com, keescook@chromium.org, dave.hansen@linux.intel.com, dan.j.williams@intel.com, linux-mm@kvack.org Subject: Re: + mm-shuffle-default-enable-all-shuffling.patch added to -mm tree Message-Id: <20190212134622.9e685e9a955915d1a058ea99@linux-foundation.org> In-Reply-To: <20190212085428.GP15609@dhcp22.suse.cz> References: <20190206200254.bcdZQ%akpm@linux-foundation.org> <20190212085428.GP15609@dhcp22.suse.cz> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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, 12 Feb 2019 09:54:28 +0100 Michal Hocko wrote: > On Wed 06-02-19 12:02:54, Andrew Morton wrote: > > From: Dan Williams > > Subject: mm/shuffle: default enable all shuffling > > > > Per Andrew's request arrange for all memory allocation shuffling code to > > be enabled by default. > > > > The page_alloc.shuffle command line parameter can still be used to disable > > shuffling at boot, but the kernel will default enable the shuffling if the > > command line option is not specified. > > > > Link: http://lkml.kernel.org/r/154943713572.3858443.11206307988382889377.stgit@dwillia2-desk3.amr.corp.intel.com > > Signed-off-by: Dan Williams > > Cc: Kees Cook > > Cc: Michal Hocko > > Cc: Dave Hansen > > Cc: Keith Busch > > > > Signed-off-by: Andrew Morton > > I hope this is mmotm only thing and even then, is this really > something we want for linux-next? There are people doing testing and > potentially performance testing on that tree. Do we want to invalidate > all that work? I can see some argument about a testing coverage but do > we really need it for the change like this? The randomization is quite > simple to review and I assume Dan has given this good testing before > submition. Please see the mailing list discussion. Without this patch the feature is likely to end up in mainline with next to no testing other than Dan's. If it disrupts people's performance testing then whoops, sorry, but we wanted to know about that!