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X-CSE-ConnectionGUID: 8i+y7gBrRsWZtqDPnPGm4Q== X-CSE-MsgGUID: 40wlsOdJSSGhmZe8SW+G1g== X-IronPort-AV: E=McAfee;i="6800,10657,11841"; a="88232219" X-IronPort-AV: E=Sophos;i="6.25,154,1779174000"; d="scan'208";a="88232219" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2026 11:30:27 -0700 X-CSE-ConnectionGUID: CreSit38SEqhU34F5Ejwog== X-CSE-MsgGUID: GyVfq50gT2Gw6mAARUjGdw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,154,1779174000"; d="scan'208";a="256580746" Received: from bradocaj-mobl.ger.corp.intel.com (HELO [10.125.111.142]) ([10.125.111.142]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2026 11:30:24 -0700 Message-ID: <6cc4354f-c494-4198-b1ad-a8b538aa1a77@intel.com> Date: Thu, 9 Jul 2026 11:30:23 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 04/10] mm/memory_hotplug: export mhp_get_default_online_type To: Gregory Price , linux-mm@kvack.org Cc: 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, djbw@kernel.org, vishal.l.verma@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 References: <20260630211842.2252800-1-gourry@gourry.net> <20260630211842.2252800-5-gourry@gourry.net> Content-Language: en-US From: Dave Jiang In-Reply-To: <20260630211842.2252800-5-gourry@gourry.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 14021160006 X-Stat-Signature: jwo914ouazcf3ouo9tekt8fpoze5ihnu X-HE-Tag: 1783621827-575988 X-HE-Meta: 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 4qYaze5l 8PfqQrolIoshRTAqS5xe8+DD7poATPOUsXTWljjVFNoEehGslhW5ggdkp4sZ8zL/C6G1P55LHTp9PzPuY7GGSwxkxC3HE0XKZxrzCaOb+xpeiGiOTT4VzwEsb/gsKIUbOO/Q2cGab18MYsLF3fTZ3NFrrolpiCaxG7krAIlH1cTMWZuWMEM113ewV1FwksOfVOKwg8cc4P3HnanpFhZuY7gvN0pL4GlJjgR9SKW/C+ujC6h532iXePZ4fHDXKv+d1B9vmCxFBTgQeTckhRR29LLD0wAFU4caPWSCR+HGYv04oKHqI6TtZTxiLJ+b1xIdPJUXf/67wwt3dLdfL+QNFpkofV7EwEvvHC2MIByjHen3yUW3uQ3v7rb6b8IuAPXAISC+TqLFaXxhz6tbYrP/19HSmbXXoKeGofuD9xMhEWWNV3u47yK5vxdaxuw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/30/26 2:18 PM, Gregory Price wrote: > Drivers which may pass hotplug policy down to DAX need MMOP_ symbols > and the mhp_get_default_online_type function for hotplug use cases. > > Some drivers (cxl) co-mingle their hotplug and devdax use-cases into > the same driver code, and chose the dax_kmem path as the default driver > path - making it difficult to require hotplug as a predicate to building > the overall driver (it may break other non-hotplug use-cases). > > Export mhp_get_default_online_type function to allow these drivers to > build when hotplug is disabled and still use the DAX use case. > > In the built-out case we simply return MMOP_OFFLINE as it's > non-destructive. The internal function can never return -1 either, > so we choose this to allow for defining the function with 'enum mmop'. > > Signed-off-by: Gregory Price > Acked-by: David Hildenbrand (Arm) Reviewed-by: Dave Jiang > --- > include/linux/memory_hotplug.h | 2 ++ > mm/memory_hotplug.c | 1 + > 2 files changed, 3 insertions(+) > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 5d4b628c4a1f..4d51fcb93a37 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -317,6 +317,8 @@ extern struct zone *zone_for_pfn_range(enum mmop online_type, > extern int arch_create_linear_mapping(int nid, u64 start, u64 size, > struct mhp_params *params); > void arch_remove_linear_mapping(u64 start, u64 size); > +#else > +static inline enum mmop mhp_get_default_online_type(void) { return MMOP_OFFLINE; } > #endif /* CONFIG_MEMORY_HOTPLUG */ > > #endif /* __LINUX_MEMORY_HOTPLUG_H */ > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 6833208cc17c..494257054095 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -239,6 +239,7 @@ enum mmop mhp_get_default_online_type(void) > > return mhp_default_online_type; > } > +EXPORT_SYMBOL_GPL(mhp_get_default_online_type); > > void mhp_set_default_online_type(enum mmop online_type) > {