Message ID | 20231206-vv-dax_abi-v2-2-f4f4f2336d08@intel.com |
---|---|
State | New |
Headers |
Return-Path: <linux-kernel-owner@vger.kernel.org> Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:bcd1:0:b0:403:3b70:6f57 with SMTP id r17csp4553379vqy; Wed, 6 Dec 2023 20:36:47 -0800 (PST) X-Google-Smtp-Source: AGHT+IGa9qJkO0dWddnIu3fnnoMYLAHnbRpVA2o5Dv9PovgAlYjF7BJ1FMZU9l0tJuGghfW64Mbb X-Received: by 2002:a17:90a:660a:b0:286:6cc1:781b with SMTP id l10-20020a17090a660a00b002866cc1781bmr2129395pjj.94.1701923807441; Wed, 06 Dec 2023 20:36:47 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1701923807; cv=none; d=google.com; s=arc-20160816; b=UooTeg26ntceK2LGUSqjh7D6QcVlCndYsPCCkZzKNQcWFWnPIFFEv6LWs177dxgm1d 5FHYCHL0bavylEvFJI5avrnQzrsMTJYxtTJs/ZKNXPGJM9M/4Kz8BKbX7AArhuALUlyZ g+xx/yMGjuCJfbWF+b/ppliceiw67IrYUPyHjdJ+Nosl3Dt6tDgnNMsahjHjQqnJzJ0C teiWc+wDgfraV5C2y54gYzewFiIKePvSLR2nM/cKEBng3EjLCgeW1C9LzF2AFx/KLpSU 3Y9go2ymyG/jZNwGztpcgu2RwQP5Y7yFbkUkf3AtmZXDGxp0EFkYVIE/7gPzRjab2ROe cYWQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:in-reply-to:references:message-id :content-transfer-encoding:mime-version:subject:date:from :dkim-signature; bh=MLd0qhASlQ85xAWcyv7h/W9riIqLqjmj76f3kMIgcwI=; fh=C1z4TcJ8nNma5YAz1Ryxr0a/S4W3aZVdFd4B3sd28Kk=; b=FG8afetQwQjByi7SH8BZBEExEiuQLOexjSCLu4hDxb50SSkOKzXj4aSRt4jh+msvaM vbGAquXKzUeJXnIPIIf2j1DAY6Lct2aCf6uoMYH0+72mGHL78BgUk9lcaESDabG/Gaa7 dSzRGWnbR9uWhGXFFkC5t5xv66PsqJh5ZyeV5R/82wOn1Qb8Te+UHqY+UjSC0wGJnpp7 geZvzruvxwbBn8XqLZmt9waLNP8pEhX/o7QcxjXJmddPNiGPNt+WaM6sNkzanbgohcz3 0vGNMsSYS6z913w+yGVQPPJJF5LKBIdmLQ9oWS+19XDv135OEywhKM81PeXU2zeunwVq /70A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=X8ibD31H; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from howler.vger.email (howler.vger.email. [23.128.96.34]) by mx.google.com with ESMTPS id ie2-20020a17090b400200b002865967fa43si363822pjb.112.2023.12.06.20.36.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 20:36:47 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) client-ip=23.128.96.34; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=X8ibD31H; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.34 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by howler.vger.email (Postfix) with ESMTP id 6926C83EE9E1; Wed, 6 Dec 2023 20:36:28 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at howler.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229841AbjLGEgQ (ORCPT <rfc822;pusanteemu@gmail.com> + 99 others); Wed, 6 Dec 2023 23:36:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229552AbjLGEgN (ORCPT <rfc822;linux-kernel@vger.kernel.org>); Wed, 6 Dec 2023 23:36:13 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE091126; Wed, 6 Dec 2023 20:36:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701923779; x=1733459779; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=GLP9N2ferQtSs1kZ5RuoBDkk5vqBcdypuQXPjkQVI40=; b=X8ibD31HmjD6dEsDuWjAgiWKn+hA7mbiNP6hjPU98obC9wFJihP0jgww sDbBe/GUyaVDqnYe9p+2dSbG8eaPjQj1E+M2511LGHJujH4OcIxh+8AhU dsnMEsSH4+rWoCIP2H1H+ELP3riFep82wBlkgLsXxldbQGUi2wVubz+VE DzmZ8le5Q6p6YOqabb/hIJYVH8/r1+xBF/CSlCm4NY1FYHWXmnX3Tclju QD1D6AeH5iqYrXP6M4Pfv4MPIaWY5yAYpEx7VZfz2bmsrFc9plT0KpWOr f68Z8RAKes8s0lz/jukPPCuo+/6VpQc4omZ+1TUfpwnqGt53Y0jnne9xY w==; X-IronPort-AV: E=McAfee;i="6600,9927,10916"; a="1053229" X-IronPort-AV: E=Sophos;i="6.04,256,1695711600"; d="scan'208";a="1053229" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Dec 2023 20:36:18 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.04,256,1695711600"; d="scan'208";a="19570383" Received: from apbrezen-mobl.amr.corp.intel.com (HELO [192.168.1.200]) ([10.213.160.175]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Dec 2023 20:36:18 -0800 From: Vishal Verma <vishal.l.verma@intel.com> Date: Wed, 06 Dec 2023 21:36:15 -0700 Subject: [PATCH v2 2/2] dax: add a sysfs knob to control memmap_on_memory behavior MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20231206-vv-dax_abi-v2-2-f4f4f2336d08@intel.com> References: <20231206-vv-dax_abi-v2-0-f4f4f2336d08@intel.com> In-Reply-To: <20231206-vv-dax_abi-v2-0-f4f4f2336d08@intel.com> To: Dave Jiang <dave.jiang@intel.com> Cc: Dan Williams <dan.j.williams@intel.com>, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Vishal Verma <vishal.l.verma@intel.com>, David Hildenbrand <david@redhat.com>, Dave Hansen <dave.hansen@linux.intel.com>, Huang Ying <ying.huang@intel.com>, Jonathan Cameron <Jonathan.Cameron@huawei.com> X-Mailer: b4 0.13-dev-26615 X-Developer-Signature: v=1; a=openpgp-sha256; l=3572; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=GLP9N2ferQtSs1kZ5RuoBDkk5vqBcdypuQXPjkQVI40=; b=owGbwMvMwCXGf25diOft7jLG02pJDKmF3gcKzPfKbereozs7go1h30Gr2z0vtixXrP9WH6aV0 WHGt+ZHRykLgxgXg6yYIsvfPR8Zj8ltz+cJTHCEmcPKBDKEgYtTACZyspDhN8uE/G1d5ypauhc5 5IRuu+B2hOnShtvJ7DXprIF6ZywyzRn+8DjbsxYyqgbaKfAVlauEsdSHtL+9VmC32TWz50b1pt/ 8AA== X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on howler.vger.email Precedence: bulk List-ID: <linux-kernel.vger.kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Wed, 06 Dec 2023 20:36:28 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1784596458482773704 X-GMAIL-MSGID: 1784596458482773704 |
Series |
Add DAX ABI for memmap_on_memory
|
|
Commit Message
Verma, Vishal L
Dec. 7, 2023, 4:36 a.m. UTC
Add a sysfs knob for dax devices to control the memmap_on_memory setting if the dax device were to be hotplugged as system memory. The default memmap_on_memory setting for dax devices originating via pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to preserve legacy behavior. For dax devices via CXL, the default is on. The sysfs control allows the administrator to override the above defaults if needed. Cc: David Hildenbrand <david@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> --- drivers/dax/bus.c | 40 +++++++++++++++++++++++++++++++++ Documentation/ABI/testing/sysfs-bus-dax | 13 +++++++++++ 2 files changed, 53 insertions(+)
Comments
Hi Vishal, On 07/12/2023 12:36, Vishal Verma wrote: > + > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > +Date: October, 2023 > +KernelVersion: v6.8 > +Contact: nvdimm@lists.linux.dev > +Description: > + (RW) Control the memmap_on_memory setting if the dax device > + were to be hotplugged as system memory. This determines whether > + the 'altmap' for the hotplugged memory will be placed on the > + device being hotplugged (memmap_on+memory=1) or if it will be s/memmap_on+memory=1/memmap_on_memory=1 I have a question here What relationship about memmap_on_memory and 'ndctl-create-namespace -M' option which specifies where is the vmemmap backed memory. I'm confused that memmap_on_memory=1 and '-M dev' are the same for nvdimm devdax mode ? ndctl-create-namespace ... -M, --map= A pmem namespace in "fsdax" or "devdax" mode requires allocation of per-page metadata. The allocation can be drawn from either: • "mem": typical system memory • "dev": persistent memory reserved from the namespace :: Given relative capacities of "Persistent Memory" to "System RAM" the allocation defaults to reserving space out of the namespace directly ("--map=dev"). The overhead is 64-bytes per 4K (16GB per 1TB) on x86. Thanks Zhijian > + placed on regular memory (memmap_on_memory=0). This attribute > + must be set before the device is handed over to the 'kmem'
On Thu, 2023-12-07 at 08:29 +0000, Zhijian Li (Fujitsu) wrote: > Hi Vishal, > > > On 07/12/2023 12:36, Vishal Verma wrote: > > + > > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > > +Date: October, 2023 > > +KernelVersion: v6.8 > > +Contact: nvdimm@lists.linux.dev > > +Description: > > + (RW) Control the memmap_on_memory setting if the dax device > > + were to be hotplugged as system memory. This determines whether > > + the 'altmap' for the hotplugged memory will be placed on the > > + device being hotplugged (memmap_on+memory=1) or if it will be > > s/memmap_on+memory=1/memmap_on_memory=1 Thanks, will fix. > > > I have a question here > > What relationship about memmap_on_memory and 'ndctl-create-namespace > -M' option which > specifies where is the vmemmap backed memory. > I'm confused that memmap_on_memory=1 and '-M dev' are the same for > nvdimm devdax mode ? > The main difference is that memory that comes from non-nvdimm sources, such as hmem, or cxl, doesn't have a chance to set up the altmaps as pmem can with '-M dev'. For these, memmap_on_memory does this as part of the memory hotplug.
Vishal Verma <vishal.l.verma@intel.com> writes: > Add a sysfs knob for dax devices to control the memmap_on_memory setting > if the dax device were to be hotplugged as system memory. > > The default memmap_on_memory setting for dax devices originating via > pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to > preserve legacy behavior. For dax devices via CXL, the default is on. > The sysfs control allows the administrator to override the above > defaults if needed. > > Cc: David Hildenbrand <david@redhat.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Dave Jiang <dave.jiang@intel.com> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Huang Ying <ying.huang@intel.com> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Reviewed-by: David Hildenbrand <david@redhat.com> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> > --- > drivers/dax/bus.c | 40 +++++++++++++++++++++++++++++++++ > Documentation/ABI/testing/sysfs-bus-dax | 13 +++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 1ff1ab5fa105..11abb57cc031 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -1270,6 +1270,45 @@ static ssize_t numa_node_show(struct device *dev, > } > static DEVICE_ATTR_RO(numa_node); > > +static ssize_t memmap_on_memory_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct dev_dax *dev_dax = to_dev_dax(dev); > + > + return sprintf(buf, "%d\n", dev_dax->memmap_on_memory); > +} > + > +static ssize_t memmap_on_memory_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct dev_dax *dev_dax = to_dev_dax(dev); > + struct dax_region *dax_region = dev_dax->region; > + ssize_t rc; > + bool val; > + > + rc = kstrtobool(buf, &val); > + if (rc) > + return rc; > + > + if (dev_dax->memmap_on_memory == val) > + return len; > + > + device_lock(dax_region->dev); > + if (!dax_region->dev->driver) { This still doesn't look right. Can we check whether the current driver is kmem? And only allow change if it's not kmem? -- Best Regards, Huang, Ying > + device_unlock(dax_region->dev); > + return -ENXIO; > + } > + > + device_lock(dev); > + dev_dax->memmap_on_memory = val; > + device_unlock(dev); > + > + device_unlock(dax_region->dev); > + return rc == 0 ? len : rc; > +} > +static DEVICE_ATTR_RW(memmap_on_memory); > + > static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n) > { > struct device *dev = container_of(kobj, struct device, kobj); > @@ -1296,6 +1335,7 @@ static struct attribute *dev_dax_attributes[] = { > &dev_attr_align.attr, > &dev_attr_resource.attr, > &dev_attr_numa_node.attr, > + &dev_attr_memmap_on_memory.attr, > NULL, > }; > > diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax > index a61a7b186017..bb063a004e41 100644 > --- a/Documentation/ABI/testing/sysfs-bus-dax > +++ b/Documentation/ABI/testing/sysfs-bus-dax > @@ -149,3 +149,16 @@ KernelVersion: v5.1 > Contact: nvdimm@lists.linux.dev > Description: > (RO) The id attribute indicates the region id of a dax region. > + > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > +Date: October, 2023 > +KernelVersion: v6.8 > +Contact: nvdimm@lists.linux.dev > +Description: > + (RW) Control the memmap_on_memory setting if the dax device > + were to be hotplugged as system memory. This determines whether > + the 'altmap' for the hotplugged memory will be placed on the > + device being hotplugged (memmap_on+memory=1) or if it will be > + placed on regular memory (memmap_on_memory=0). This attribute > + must be set before the device is handed over to the 'kmem' > + driver (i.e. hotplugged into system-ram).
On 08/12/2023 03:25, Verma, Vishal L wrote: > On Thu, 2023-12-07 at 08:29 +0000, Zhijian Li (Fujitsu) wrote: >> Hi Vishal, >> >> >> On 07/12/2023 12:36, Vishal Verma wrote: >>> + >>> +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory >>> +Date: October, 2023 >>> +KernelVersion: v6.8 >>> +Contact: nvdimm@lists.linux.dev >>> +Description: >>> + (RW) Control the memmap_on_memory setting if the dax device >>> + were to be hotplugged as system memory. This determines whether >>> + the 'altmap' for the hotplugged memory will be placed on the >>> + device being hotplugged (memmap_on+memory=1) or if it will be >> >> s/memmap_on+memory=1/memmap_on_memory=1 > > Thanks, will fix. >> >> >> I have a question here >> >> What relationship about memmap_on_memory and 'ndctl-create-namespace >> -M' option which >> specifies where is the vmemmap backed memory. >> I'm confused that memmap_on_memory=1 and '-M dev' are the same for >> nvdimm devdax mode ? >> > The main difference is that memory that comes from non-nvdimm sources, > such as hmem, or cxl, doesn't have a chance to set up the altmaps as > pmem can with '-M dev'. For these, memmap_on_memory does this as part > of the memory hotplug. Thanks for your explanation. (I wrongly thought nvdimm.kmem was also controlled by '-M dev' before) feel free add: Tested-by: Li Zhijian <lizhijian@fujitsu.com>
On 07.12.23 05:36, Vishal Verma wrote: > Add a sysfs knob for dax devices to control the memmap_on_memory setting > if the dax device were to be hotplugged as system memory. > > The default memmap_on_memory setting for dax devices originating via > pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to > preserve legacy behavior. For dax devices via CXL, the default is on. > The sysfs control allows the administrator to override the above > defaults if needed. > > Cc: David Hildenbrand <david@redhat.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Dave Jiang <dave.jiang@intel.com> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Huang Ying <ying.huang@intel.com> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > Reviewed-by: David Hildenbrand <david@redhat.com> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> > --- > drivers/dax/bus.c | 40 +++++++++++++++++++++++++++++++++ > Documentation/ABI/testing/sysfs-bus-dax | 13 +++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 1ff1ab5fa105..11abb57cc031 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -1270,6 +1270,45 @@ static ssize_t numa_node_show(struct device *dev, > } > static DEVICE_ATTR_RO(numa_node); > > +static ssize_t memmap_on_memory_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct dev_dax *dev_dax = to_dev_dax(dev); > + > + return sprintf(buf, "%d\n", dev_dax->memmap_on_memory); > +} > + > +static ssize_t memmap_on_memory_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t len) > +{ > + struct dev_dax *dev_dax = to_dev_dax(dev); > + struct dax_region *dax_region = dev_dax->region; > + ssize_t rc; > + bool val; > + > + rc = kstrtobool(buf, &val); > + if (rc) > + return rc; > + > + if (dev_dax->memmap_on_memory == val) > + return len; > + > + device_lock(dax_region->dev); > + if (!dax_region->dev->driver) { > + device_unlock(dax_region->dev); > + return -ENXIO; > + } > + > + device_lock(dev); > + dev_dax->memmap_on_memory = val; > + device_unlock(dev); > + > + device_unlock(dax_region->dev); > + return rc == 0 ? len : rc; > +} > +static DEVICE_ATTR_RW(memmap_on_memory); > + > static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n) > { > struct device *dev = container_of(kobj, struct device, kobj); > @@ -1296,6 +1335,7 @@ static struct attribute *dev_dax_attributes[] = { > &dev_attr_align.attr, > &dev_attr_resource.attr, > &dev_attr_numa_node.attr, > + &dev_attr_memmap_on_memory.attr, > NULL, > }; > > diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax > index a61a7b186017..bb063a004e41 100644 > --- a/Documentation/ABI/testing/sysfs-bus-dax > +++ b/Documentation/ABI/testing/sysfs-bus-dax > @@ -149,3 +149,16 @@ KernelVersion: v5.1 > Contact: nvdimm@lists.linux.dev > Description: > (RO) The id attribute indicates the region id of a dax region. > + > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > +Date: October, 2023 > +KernelVersion: v6.8 > +Contact: nvdimm@lists.linux.dev > +Description: > + (RW) Control the memmap_on_memory setting if the dax device > + were to be hotplugged as system memory. This determines whether > + the 'altmap' for the hotplugged memory will be placed on the > + device being hotplugged (memmap_on+memory=1) or if it will be > + placed on regular memory (memmap_on_memory=0). This attribute > + must be set before the device is handed over to the 'kmem' > + driver (i.e. hotplugged into system-ram). > Should we note the dependency on other factors as given in mhp_supports_memmap_on_memory(), especially, the system-wide setting and some weird kernel configurations?
On Fri, 2023-12-08 at 09:20 +0000, Zhijian Li (Fujitsu) wrote: > > > On 08/12/2023 03:25, Verma, Vishal L wrote: > > On Thu, 2023-12-07 at 08:29 +0000, Zhijian Li (Fujitsu) wrote: > > > Hi Vishal, > > > > > > > > > On 07/12/2023 12:36, Vishal Verma wrote: > > > > + > > > > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > > > > +Date: October, 2023 > > > > +KernelVersion: v6.8 > > > > +Contact: nvdimm@lists.linux.dev > > > > +Description: > > > > + (RW) Control the memmap_on_memory setting if the dax device > > > > + were to be hotplugged as system memory. This determines whether > > > > + the 'altmap' for the hotplugged memory will be placed on the > > > > + device being hotplugged (memmap_on+memory=1) or if it will be > > > > > > s/memmap_on+memory=1/memmap_on_memory=1 > > > > Thanks, will fix. > > > > > > > > > I have a question here > > > > > > What relationship about memmap_on_memory and 'ndctl-create-namespace > > > -M' option which > > > specifies where is the vmemmap backed memory. > > > I'm confused that memmap_on_memory=1 and '-M dev' are the same for > > > nvdimm devdax mode ? > > > > > The main difference is that memory that comes from non-nvdimm sources, > > such as hmem, or cxl, doesn't have a chance to set up the altmaps as > > pmem can with '-M dev'. For these, memmap_on_memory does this as part > > of the memory hotplug. > > Thanks for your explanation. > (I wrongly thought nvdimm.kmem was also controlled by '-M dev' before) > > feel free add: > Tested-by: Li Zhijian <lizhijian@fujitsu.com> Thank you Zhijian!
On Fri, 2023-12-08 at 11:13 +0800, Huang, Ying wrote: > Vishal Verma <vishal.l.verma@intel.com> writes: > [..] > > > > + > > +static ssize_t memmap_on_memory_store(struct device *dev, > > + struct device_attribute *attr, > > + const char *buf, size_t len) > > +{ > > + struct dev_dax *dev_dax = to_dev_dax(dev); > > + struct dax_region *dax_region = dev_dax->region; > > + ssize_t rc; > > + bool val; > > + > > + rc = kstrtobool(buf, &val); > > + if (rc) > > + return rc; > > + > > + if (dev_dax->memmap_on_memory == val) > > + return len; > > + > > + device_lock(dax_region->dev); > > + if (!dax_region->dev->driver) { > > This still doesn't look right. Can we check whether the current driver > is kmem? And only allow change if it's not kmem? Ah yes I lost track of this todo between revisions when I split this out. Let me fix that for the next revision.
On Fri, 2023-12-08 at 12:36 +0100, David Hildenbrand wrote: > On 07.12.23 05:36, Vishal Verma wrote: [..] > > > > + > > +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory > > +Date: October, 2023 > > +KernelVersion: v6.8 > > +Contact: nvdimm@lists.linux.dev > > +Description: > > + (RW) Control the memmap_on_memory setting if the dax device > > + were to be hotplugged as system memory. This determines whether > > + the 'altmap' for the hotplugged memory will be placed on the > > + device being hotplugged (memmap_on+memory=1) or if it will be > > + placed on regular memory (memmap_on_memory=0). This attribute > > + must be set before the device is handed over to the 'kmem' > > + driver (i.e. hotplugged into system-ram). > > > > Should we note the dependency on other factors as given in > mhp_supports_memmap_on_memory(), especially, the system-wide setting and > some weird kernel configurations? > Yep good idea, I'll make a note of those for v3.
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 1ff1ab5fa105..11abb57cc031 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1270,6 +1270,45 @@ static ssize_t numa_node_show(struct device *dev, } static DEVICE_ATTR_RO(numa_node); +static ssize_t memmap_on_memory_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dev_dax *dev_dax = to_dev_dax(dev); + + return sprintf(buf, "%d\n", dev_dax->memmap_on_memory); +} + +static ssize_t memmap_on_memory_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct dev_dax *dev_dax = to_dev_dax(dev); + struct dax_region *dax_region = dev_dax->region; + ssize_t rc; + bool val; + + rc = kstrtobool(buf, &val); + if (rc) + return rc; + + if (dev_dax->memmap_on_memory == val) + return len; + + device_lock(dax_region->dev); + if (!dax_region->dev->driver) { + device_unlock(dax_region->dev); + return -ENXIO; + } + + device_lock(dev); + dev_dax->memmap_on_memory = val; + device_unlock(dev); + + device_unlock(dax_region->dev); + return rc == 0 ? len : rc; +} +static DEVICE_ATTR_RW(memmap_on_memory); + static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n) { struct device *dev = container_of(kobj, struct device, kobj); @@ -1296,6 +1335,7 @@ static struct attribute *dev_dax_attributes[] = { &dev_attr_align.attr, &dev_attr_resource.attr, &dev_attr_numa_node.attr, + &dev_attr_memmap_on_memory.attr, NULL, }; diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax index a61a7b186017..bb063a004e41 100644 --- a/Documentation/ABI/testing/sysfs-bus-dax +++ b/Documentation/ABI/testing/sysfs-bus-dax @@ -149,3 +149,16 @@ KernelVersion: v5.1 Contact: nvdimm@lists.linux.dev Description: (RO) The id attribute indicates the region id of a dax region. + +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory +Date: October, 2023 +KernelVersion: v6.8 +Contact: nvdimm@lists.linux.dev +Description: + (RW) Control the memmap_on_memory setting if the dax device + were to be hotplugged as system memory. This determines whether + the 'altmap' for the hotplugged memory will be placed on the + device being hotplugged (memmap_on+memory=1) or if it will be + placed on regular memory (memmap_on_memory=0). This attribute + must be set before the device is handed over to the 'kmem' + driver (i.e. hotplugged into system-ram).