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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-92ee5cf78a5sm97038385a.31.2026.07.09.20.08.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 20:08:53 -0700 (PDT) Date: Thu, 9 Jul 2026 23:08:48 -0400 From: Gregory Price To: "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 Subject: Re: [PATCH v6 09/10] dax/kmem: add sysfs interface for atomic whole-device hotplug Message-ID: References: <20260630211842.2252800-1-gourry@gourry.net> <20260630211842.2252800-10-gourry@gourry.net> <6a502267b17cc_3b7ee51008f@djbw-dev.notmuch> <6a50356aa7a4a_3cabcb1008a@djbw-dev.notmuch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6a50356aa7a4a_3cabcb1008a@djbw-dev.notmuch> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3210540002 X-Stat-Signature: yxpt7auu77yt4ikwag4okr6uqffueker X-HE-Tag: 1783652936-450938 X-HE-Meta: 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 eiC8/QmG 6Tt1jSvchINc5KBIX5zJeiy7iQ0d7JF3GEmivr+/jYtfEChxIuQ6U3iRSxjr3lEz6aFajH6jv3hZlSH4kspav8jgtdTPCOT9rAl6h/MT19Y/sfBKLG9L970bxfGRSxLPbcNFJofoCsz7xwb5eaDdaNIt3q+q9Tz0cV4FRBecuqzDnw8TFlMQT9ZPC1Xg0OTkLVgoKjJSnr3yF9TN+KlWHJ3T1XrogOGxOf/DxoC9/oTjKhFcr7PZ9d9nE8FlxZykUpwsMJq44RpyhAj5ojrZw4UokFtou9cjEcV3KggwcWnRvQzD0frL5jrS6PACGlyMp+UpFJVubYEs7h7MiHChzGpdlusDOfkS7pOPmY7slh8BTsEqa6Rg6US5VCC3FwUxtsMAt4N1aLhWLrwX7McQgtM5ynw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 09, 2026 at 04:57:30PM -0700, Dan Williams (nvidia) wrote: > 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. Ah, you know, on second look - DAX could never reach this BUG() in the first place. I think this was a hold-over from when i was originally refactoring and trying to figure out the right path. If there's a desire to soften these BUG() to WARN(), i can submit that separately, but i will close this all out with some comment updates.