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Thu, 9 Jul 2026 19:57:31 -0400 (EDT) Date: Thu, 09 Jul 2026 16:57:30 -0700 From: "Dan Williams (nvidia)" To: Gregory Price , "Dan Williams (nvidia)" Cc: linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, driver-core@lists.linux.dev, linux-kselftest@vger.kernel.org, kernel-team@meta.com, david@kernel.org, osalvador@suse.de, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, alison.schofield@intel.com, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, iweiny@kernel.org, Smita.KoralahalliChannabasappa@amd.com, apopple@nvidia.com, Hannes Reinecke Message-ID: <6a50356aa7a4a_3cabcb1008a@djbw-dev.notmuch> In-Reply-To: References: <20260630211842.2252800-1-gourry@gourry.net> <20260630211842.2252800-10-gourry@gourry.net> <6a502267b17cc_3b7ee51008f@djbw-dev.notmuch> Subject: Re: [PATCH v6 09/10] dax/kmem: add sysfs interface for atomic whole-device hotplug Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3635B40005 X-Stat-Signature: 373mj58ohcc4n3bpmoaxb96iemi1ihnb X-HE-Tag: 1783641455-95386 X-HE-Meta: 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 sElU4sXi Hh/3HOK/NWTA62EDlWN/68QEGi1bpdkYNpFkQaQo9+Gxo9iCBmW0YB5M9Qmbl55BI7lhJbrI9gSXhhc+qJIC232FcyeAN9sgQ+mD/7VmnYv+ywXluyr4JGiKOOTsgEQEFtEldA8sP/TfAIYR3zvVgxyILhE+71fJv4zsWtUovNxTdx9HWyEAedwMhDXw0W0ek+gmlo//cwqTkdlNuxY2EB3LLm5zCspI+lJLtaEvMNgmYx3Ja+WrvoR8Zc0ILm/EiPr5HCSzdaslr7AT9gNCnyrzO6hPBMML19qvA7zoozPfAphXdwKt2Y5mgZ4pWJoPCyubvag/wuIzZQS7Kg1EyFq6j/A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Gregory Price wrote: > > So the "unknown" case does not need to be here. > > > > mhp_online_type_to_str can technically return NULL, seems better to not > just let a NULL dereference sit latent even if we can visually tell it > can't happen today? Oh, makes sense I was thinking "unknown" was only a result of the drvdata missing case. > > > + if (dax_kmem_state_is_online(data->state)) { > > > + dev_warn(dev, "Hotplug regions stuck online until reboot\n"); > > > > I like that the BUG() is avoided, but I think these should stay > > dev_err() given the severity. > > > > I had to go back to calling remove_memory() by default given different > feedback, but I think if anything I will just modify the BUG() to a > WARN() and call it a day. ack.