From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 BA9073C9432; Mon, 23 Mar 2026 17:31:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774287107; cv=none; b=DJdnWSVyfElj7J35Vkab9nr5u+2F01lvJ/3ObG4Pp0BZU8JOCmxI3YLy/jcFfJNx+H6aZOz8k7h02mthxrmYpE0zgSCCpc59JpealV8e8wQ3BnVk3/5xjEoaYI+LcQjjpPtfI/mylAGIIwtXa1x85IQOqaizvmkbvbt98vk5vH8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774287107; c=relaxed/simple; bh=go7NgkHXgfn9/qJxOGRIORTyJcHQqG1yRjvleSKosIo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AMiXoHVhcLWxk+w3Al8VXFnwwNXGTJ3T/9Qv0WlotodG9gk4hXSmLfwUESSrD8gNTnpDJoGgTZBHZjHckxHssT8dUtspMpi0gSDZzpAG5kXTAvOb74+EFAq3KIW0AsZ5DsCZcNnymGRKVyMw0N/Oidlc8mABd3uobhL7Y1eivSk= 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=SDDC3anb; arc=none smtp.client-ip=192.198.163.8 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="SDDC3anb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1774287106; x=1805823106; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=go7NgkHXgfn9/qJxOGRIORTyJcHQqG1yRjvleSKosIo=; b=SDDC3anbImPKshdbwGGD5NNkb7Qd4G9x2GtaqAOhz5wXVngN1i4ltBnE VtYmQQbX2u+27pZqatperrcuCVQP8y9YXMDMG3S299nW41v3Wq7RoEALk LP4Ttgquura1UmVeqPDzUxxM9IYljuJeYf4gl4MGB4IkMD2dSZZ/P5XWA f4hfMjPK8YC8UH5yWAFBEQEfdlD2DsGv1Ndl1HiFAkqPFArLyENjIWoTo 611JqTV5ozGPU5s74IQYlPs0nmhbk9zwUIuA4aNYiRayasCzpVHQgRZhQ Kd5PcQpM4uqNdz8C0D2I/VWC3cDLQlvCAcdtCwd3043IcMOHJQv9wQTLU g==; X-CSE-ConnectionGUID: 6q/wMO8ITRWLcVW9H9mGQA== X-CSE-MsgGUID: ON/TxvdmQzuiuQ0SiI9pmA== X-IronPort-AV: E=McAfee;i="6800,10657,11738"; a="92865794" X-IronPort-AV: E=Sophos;i="6.23,137,1770624000"; d="scan'208";a="92865794" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2026 10:31:45 -0700 X-CSE-ConnectionGUID: +feu5u54RyWgIHocjrb6Ew== X-CSE-MsgGUID: LV7OoE3hR/294sFk1B+y4g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,137,1770624000"; d="scan'208";a="224064255" Received: from jdoman-mobl3.amr.corp.intel.com (HELO [10.125.109.216]) ([10.125.109.216]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2026 10:31:42 -0700 Message-ID: Date: Mon, 23 Mar 2026 10:31:41 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 6/9] dax: Track all dax_region allocations under a global resource tree To: Smita Koralahalli , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org Cc: Ard Biesheuvel , Alison Schofield , Vishal Verma , Ira Weiny , Dan Williams , Jonathan Cameron , Yazen Ghannam , Davidlohr Bueso , Matthew Wilcox , Jan Kara , "Rafael J . Wysocki" , Len Brown , Pavel Machek , Li Ming , Jeff Johnson , Ying Huang , Yao Xingtao , Peter Zijlstra , Greg Kroah-Hartman , Nathan Fontenot , Terry Bowman , Robert Richter , Benjamin Cheatham , Zhijian Li , Borislav Petkov , Tomasz Wolski References: <20260322195343.206900-1-Smita.KoralahalliChannabasappa@amd.com> <20260322195343.206900-7-Smita.KoralahalliChannabasappa@amd.com> Content-Language: en-US From: Dave Jiang In-Reply-To: <20260322195343.206900-7-Smita.KoralahalliChannabasappa@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/22/26 12:53 PM, Smita Koralahalli wrote: > Introduce a global "DAX Regions" resource root and register each > dax_region->res under it via request_resource(). Release the resource on > dax_region teardown. > > By enforcing a single global namespace for dax_region allocations, this > ensures only one of dax_hmem or dax_cxl can successfully register a > dax_region for a given range. > > Suggested-by: Dan Williams > Signed-off-by: Smita Koralahalli > Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang > --- > drivers/dax/bus.c | 20 +++++++++++++++++--- > 1 file changed, 17 insertions(+), 3 deletions(-) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 299134c9b294..68437c05e21d 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -10,6 +10,7 @@ > #include "dax-private.h" > #include "bus.h" > > +static struct resource dax_regions = DEFINE_RES_MEM_NAMED(0, -1, "DAX Regions"); > static DEFINE_MUTEX(dax_bus_lock); > > /* > @@ -627,6 +628,7 @@ static void dax_region_unregister(void *region) > > sysfs_remove_groups(&dax_region->dev->kobj, > dax_region_attribute_groups); > + release_resource(&dax_region->res); > dax_region_put(dax_region); > } > > @@ -635,6 +637,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id, > unsigned long flags) > { > struct dax_region *dax_region; > + int rc; > > /* > * The DAX core assumes that it can store its private data in > @@ -667,14 +670,25 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id, > .flags = IORESOURCE_MEM | flags, > }; > > - if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) { > - dax_region_put(dax_region); > - return NULL; > + rc = request_resource(&dax_regions, &dax_region->res); > + if (rc) { > + dev_dbg(parent, "dax_region resource conflict for %pR\n", > + &dax_region->res); > + goto err_res; > } > > + if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) > + goto err_sysfs; > + > if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region)) > return NULL; > return dax_region; > + > +err_sysfs: > + release_resource(&dax_region->res); > +err_res: > + dax_region_put(dax_region); > + return NULL; > } > EXPORT_SYMBOL_GPL(alloc_dax_region); >