From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F62A449983; Thu, 9 Jul 2026 18:48:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783622929; cv=none; b=g0akSuD/U1Qqrc7RoiEwArHjTJ4jEKzZbch0IhE92YT1vpOJj9EEBTOCP9Q29YGO+cMCJAy+/MdWLFED5tcD18O27YAEObCZTN4q44VRA/Grv7Th/CHPzbyN/rFTT9YhT+E4NjNgDfuYAepKOa9FkodvdkDvk0U9tzzRr1lqGSk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783622929; c=relaxed/simple; bh=eQe38nCcFVma1LFoo+FfKYEwuC+uAK1QDlLMvNStl/w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=a2rfI2NmyP0bUa0s1fs6ikKt8GYXpFAAHJr8EpnaE3MfD8C9jN3BM2n0Q7+8osiFbwyXQQLp4pLEkaARCMysUwuFEeZm4h5PGrxh0W5w9Lv6ZSDktnzNjYcYWXXV8vv3NIYiGBZEHiYumEyt9CQ5A89fTVtuPGy86TQza2BFi8g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=A4V9I73E; arc=none smtp.client-ip=198.175.65.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="A4V9I73E" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1783622926; x=1815158926; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=eQe38nCcFVma1LFoo+FfKYEwuC+uAK1QDlLMvNStl/w=; b=A4V9I73ErKuPhUmkpqwVvKDqQzGKaKapXs+8k+IgIjPl1m2txS/eslGe ov5k2Zj+61uJ0No/lEUzGlkkqGIZvCe5+hTqGz21rOnevjvBsA1UiNYnR 6vpHZAsBQ3Wg/et8KHaxcX1WvMZdhD4/YGv54AghdQ/WmF4ZfQZSJPLgb rRWjxlzb/jGJTOmzmGJVBiraa4WkD2oNkOqvOBDoHacfojZKVSbEQyGHD q1aR1rM1SEDRbQu/+1Suw/XdBBvqD2VnIh2jAujToiPnwcdrshdTnDRTK QotkPGxxwVsJNyZ8KIUV6HzINzee4kymIlACa7p3oAwWAnLhVfAcGc32W Q==; X-CSE-ConnectionGUID: RuuJcIqJQsWrv8kzGbjdZA== X-CSE-MsgGUID: vLAns/mSQx6+mHqk+jIRiA== X-IronPort-AV: E=McAfee;i="6800,10657,11841"; a="84510524" X-IronPort-AV: E=Sophos;i="6.25,154,1779174000"; d="scan'208";a="84510524" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2026 11:48:39 -0700 X-CSE-ConnectionGUID: kYtsmSMOTf29rCwwFr7afQ== X-CSE-MsgGUID: KmQqYJpaQhGKsg7QNVCUnw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,154,1779174000"; d="scan'208";a="252932157" Received: from bradocaj-mobl.ger.corp.intel.com (HELO [10.125.111.142]) ([10.125.111.142]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2026 11:48:37 -0700 Message-ID: Date: Thu, 9 Jul 2026 11:48:36 -0700 Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 05/10] mm/memory_hotplug: add __add_memory_driver_managed() with online_type arg 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, Pankaj Gupta References: <20260630211842.2252800-1-gourry@gourry.net> <20260630211842.2252800-6-gourry@gourry.net> Content-Language: en-US From: Dave Jiang In-Reply-To: <20260630211842.2252800-6-gourry@gourry.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/30/26 2:18 PM, Gregory Price wrote: > Existing callers of add_memory_driver_managed cannot select the > preferred online type (ZONE_NORMAL vs ZONE_MOVABLE), requiring it to > hot-add memory as offline blocks, and then follow up by onlining each > memory block individually. > > Most drivers prefer the system default, but the CXL driver wants to > plumb a preferred policy through the dax kmem driver. > > Refactor APIs to add a new interface which allows the dax kmem module > to select a preferred policy. > > Overriding the configured auto-online policy is only safe for known > in-tree modules, where we know the override reflects a different, > user-requested policy. We do not want arbitrary out-of-tree drivers > silently overriding the system-wide onlining policy, so restrict the > new interface to the kmem module using EXPORT_SYMBOL_FOR_MODULES() > rather than a plain EXPORT_SYMBOL_GPL(). Other in-tree modules (e.g. > cxl_core) can be added to the allowed list as the need arises. > > Refactor add_memory_driver_managed, extract __add_memory_driver_managed > - Add proper kernel-doc for add_memory_driver_managed while refactoring > - New helper accepts an explicit online_type. > - New helper validates online_type is between OFFLINE and ONLINE_MOVABLE > > Refactor: add_memory_resource, extract __add_memory_resource > - new helper accepts an explicit online_type > > Original APIs now explicitly pass the system-default to new helpers. > > No functional change for existing users. > > Acked-by: David Hildenbrand (Arm) > Reviewed-by: Pankaj Gupta > Signed-off-by: Gregory Price Reviewed-by: Dave Jiang > --- > include/linux/memory_hotplug.h | 3 ++ > mm/memory_hotplug.c | 61 +++++++++++++++++++++++++++++----- > 2 files changed, 56 insertions(+), 8 deletions(-) > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index 4d51fcb93a37..ff3b865ea7e7 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -295,6 +295,9 @@ extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags); > extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags); > extern int add_memory_resource(int nid, struct resource *resource, > mhp_t mhp_flags); > +int __add_memory_driver_managed(int nid, u64 start, u64 size, > + const char *resource_name, mhp_t mhp_flags, > + enum mmop online_type); > extern int add_memory_driver_managed(int nid, u64 start, u64 size, > const char *resource_name, > mhp_t mhp_flags); > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 494257054095..a66346def504 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1494,10 +1494,10 @@ static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, > * > * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG > */ > -int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > +static int __add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags, > + enum mmop online_type) > { > struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) }; > - enum mmop online_type = mhp_get_default_online_type(); > enum memblock_flags memblock_flags = MEMBLOCK_NONE; > struct memory_group *group = NULL; > u64 start, size; > @@ -1585,7 +1585,7 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > merge_system_ram_resource(res); > > /* online pages if requested */ > - if (mhp_get_default_online_type() != MMOP_OFFLINE) > + if (online_type != MMOP_OFFLINE) > walk_memory_blocks(start, size, &online_type, > online_memory_block); > > @@ -1603,7 +1603,13 @@ int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > return ret; > } > > -/* requires device_hotplug_lock, see add_memory_resource() */ > +int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > +{ > + return __add_memory_resource(nid, res, mhp_flags, > + mhp_get_default_online_type()); > +} > + > +/* requires device_hotplug_lock, see __add_memory_resource() */ > int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags) > { > struct resource *res; > @@ -1631,7 +1637,15 @@ int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags) > } > EXPORT_SYMBOL_GPL(add_memory); > > -/* > +/** > + * __add_memory_driver_managed - add driver-managed memory with explicit online_type > + * @nid: NUMA node ID where the memory will be added > + * @start: Start physical address of the memory range > + * @size: Size of the memory range in bytes > + * @resource_name: Resource name in format "System RAM ($DRIVER)" > + * @mhp_flags: Memory hotplug flags > + * @online_type: Auto-Online behavior (offline, online, kernel, movable) > + * > * Add special, driver-managed memory to the system as system RAM. Such > * memory is not exposed via the raw firmware-provided memmap as system > * RAM, instead, it is detected and added by a driver - during cold boot, > @@ -1639,6 +1653,7 @@ EXPORT_SYMBOL_GPL(add_memory); > * > * Reasons why this memory should not be used for the initial memmap of a > * kexec kernel or for placing kexec images: > + * > * - The booting kernel is in charge of determining how this memory will be > * used (e.g., use persistent memory as system RAM) > * - Coordination with a hypervisor is required before this memory > @@ -1651,9 +1666,12 @@ EXPORT_SYMBOL_GPL(add_memory); > * > * The resource_name (visible via /proc/iomem) has to have the format > * "System RAM ($DRIVER)". > + * > + * Return: 0 on success, negative error code on failure. > */ > -int add_memory_driver_managed(int nid, u64 start, u64 size, > - const char *resource_name, mhp_t mhp_flags) > +int __add_memory_driver_managed(int nid, u64 start, u64 size, > + const char *resource_name, mhp_t mhp_flags, > + enum mmop online_type) > { > struct resource *res; > int rc; > @@ -1663,6 +1681,9 @@ int add_memory_driver_managed(int nid, u64 start, u64 size, > resource_name[strlen(resource_name) - 1] != ')') > return -EINVAL; > > + if (online_type < MMOP_OFFLINE || online_type > MMOP_ONLINE_MOVABLE) > + return -EINVAL; > + > lock_device_hotplug(); > > res = register_memory_resource(start, size, resource_name); > @@ -1671,7 +1692,7 @@ int add_memory_driver_managed(int nid, u64 start, u64 size, > goto out_unlock; > } > > - rc = add_memory_resource(nid, res, mhp_flags); > + rc = __add_memory_resource(nid, res, mhp_flags, online_type); > if (rc < 0) > release_memory_resource(res); > > @@ -1679,6 +1700,30 @@ int add_memory_driver_managed(int nid, u64 start, u64 size, > unlock_device_hotplug(); > return rc; > } > +EXPORT_SYMBOL_FOR_MODULES(__add_memory_driver_managed, "kmem"); > + > +/** > + * add_memory_driver_managed - add driver-managed memory > + * @nid: NUMA node ID where the memory will be added > + * @start: Start physical address of the memory range > + * @size: Size of the memory range in bytes > + * @resource_name: Resource name in format "System RAM ($DRIVER)" > + * @mhp_flags: Memory hotplug flags > + * > + * Add driver-managed memory with the system default online type set by > + * build config or kernel boot parameter. > + * > + * See __add_memory_driver_managed for more details. > + * > + * Return: 0 on success, negative error code on failure. > + */ > +int add_memory_driver_managed(int nid, u64 start, u64 size, > + const char *resource_name, mhp_t mhp_flags) > +{ > + return __add_memory_driver_managed(nid, start, size, resource_name, > + mhp_flags, > + mhp_get_default_online_type()); > +} > EXPORT_SYMBOL_GPL(add_memory_driver_managed); > > /*