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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c711b99fcbsm56868585a.18.2026.01.27.13.42.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jan 2026 13:42:43 -0800 (PST) Date: Tue, 27 Jan 2026 16:42:41 -0500 From: Gregory Price To: Andrew Morton 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: References: <20260114235022.3437787-6-gourry@gourry.net> <20260115024222.3486455-1-gourry@gourry.net> <20260127133431.671e4605eee807abe84f92f4@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260127133431.671e4605eee807abe84f92f4@linux-foundation.org> On Tue, Jan 27, 2026 at 01:34:31PM -0800, Andrew Morton wrote: > 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? > This feature is likely getting dropped in favor of pushing such policy to a driver if it cares that much to prevent users toggling memory blocks. I will likely re-spin this series in a week or so when other non-mm changes flesh out a little clearer. This will be removed and some of the mm/memory-hotplug.c changes will be changed to prevent the modification of an already extern'd function. ~Gregory