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b=DjTBNLHTNOC+jXRWsQ6HIWju6jaCg17tDZSayr8cblHACDU+z7Syip8Gie1ClWfDk YXi9aqZvE3iKKO+oV1rWm4swd+zSyWuVq6ApEnjlVtei99TwkJr9wfiAoy1CLgEKvE lAlqYtdgL6tUK0UDATd8mL/cp6frej8XW69FO5PU= Date: Tue, 27 Jan 2026 13:34:31 -0800 From: Andrew Morton To: Gregory Price Cc: linux-mm@kvack.org, linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, kernel-team@meta.com, dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, david@kernel.org, mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, osalvador@suse.de Subject: Re: [PATCH] dax/kmem: add build config for protected dax memory blocks Message-Id: <20260127133431.671e4605eee807abe84f92f4@linux-foundation.org> In-Reply-To: <20260115024222.3486455-1-gourry@gourry.net> References: <20260114235022.3437787-6-gourry@gourry.net> <20260115024222.3486455-1-gourry@gourry.net> 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-Rspamd-Server: rspam12 X-Stat-Signature: rht91e1dfpkh5c9fax5916rgcnqegopq X-Rspamd-Queue-Id: 2EB4E40007 X-Rspam-User: X-HE-Tag: 1769549674-844217 X-HE-Meta: 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 I6DP9twn zunZdOR3t+5vpgxJHf0gt8avVty6eV93+Uv82FHg87A90M5hc1Xitz16Rm3nSY9sfz3sCF2T7iVXJQQMCSNcEeXtEVpnbhT+Hllafir4vD0QJfEkGii9Emdm1z4ZCix8SbQY2SPiA6R/kvN/MSrg+wF/aIQRv102F2iAA2LKdjbTk98Rn8/jiSNy37AFqskFe1vztBGRC9cu8l1m0u8C1Eh3rmLM4s6Rpd7I2TQBAzXqawpU3vRRsiom9tz3DmXU3+mNX+3McmLXwGxZeldlKzxmVBFM2WzsR5fF26IVrvO+dKH7VfgGuZs5NBQ== 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: List-Subscribe: List-Unsubscribe: On Wed, 14 Jan 2026 21:42:22 -0500 Gregory Price wrote: > Since this protection may break userspace tools, it should > be an opt-in until those tools have time to update to the > new daxN.M/hotplug interface instead of memory blocks. > > --- a/drivers/dax/Kconfig > +++ b/drivers/dax/Kconfig > @@ -78,4 +78,22 @@ config DEV_DAX_KMEM > > Say N if unsure. > > +config DEV_DAX_KMEM_PROTECTED Users must rebuild and redeploy kernels after having updated a userspace tool. They won't thank us for this ;) Isn't there something we can do to make this feature backward-compatible?