From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BC22C433DB for ; Tue, 30 Mar 2021 15:43:22 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D0843619A7 for ; Tue, 30 Mar 2021 15:43:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0843619A7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 95BB9100EB83A; Tue, 30 Mar 2021 08:43:21 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=13.77.154.182; helo=linux.microsoft.com; envelope-from=tyhicks@linux.microsoft.com; receiver= Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by ml01.01.org (Postfix) with ESMTP id 2C45A100EB835 for ; Tue, 30 Mar 2021 08:43:18 -0700 (PDT) Received: from sequoia (162-237-133-238.lightspeed.rcsntx.sbcglobal.net [162.237.133.238]) by linux.microsoft.com (Postfix) with ESMTPSA id 3BCFB20B5680; Tue, 30 Mar 2021 08:43:17 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3BCFB20B5680 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1617118997; bh=Ex/hhLMgEI8y3lLUNawbT4uibtJe9r185X98zTx9OpQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Fbxuq7OjRALgIqrYnzNwxEn3DruP91PxGjvmVvQMXcFA5ZrGr/IQpPOPutFhR8y2z DG17Q0Rg0FvbzATQeKVAy0s3sPXOhb2vlXCFT0SCBir2g3IrhJpFHsvLSjyz/mtpAc 2vXBQQ8SMF2LfFjxTjQv/8YZTcrPi2EOXBU+3Qf0= Date: Tue, 30 Mar 2021 10:43:15 -0500 From: Tyler Hicks To: "Aneesh Kumar K.V" Subject: Re: [PATCH] libnvdimm/region: Allow setting align attribute on regions without mappings Message-ID: <20210330154315.GD4749@sequoia> References: <20210326152645.85225-1-tyhicks@linux.microsoft.com> <87h7ks7vm5.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87h7ks7vm5.fsf@linux.ibm.com> Message-ID-Hash: 5LOGXTLTBVB7XEBISVBUEQ6AZ3RUIEBY X-Message-ID-Hash: 5LOGXTLTBVB7XEBISVBUEQ6AZ3RUIEBY X-MailFrom: tyhicks@linux.microsoft.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Pavel Tatashin , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 2021-03-30 16:32:10, Aneesh Kumar K.V wrote: > Tyler Hicks writes: > > > The alignment constraint for namespace creation in a region was > > increased, from 2M to 16M, for non-PowerPC architectures in v5.7 with > > commit 2522afb86a8c ("libnvdimm/region: Introduce an 'align' > > attribute"). The thought behind the change was that region alignment > > should be uniform across all architectures and, since PowerPC had the > > largest alignment constraint of 16M, all architectures should conform to > > that alignment. > > > > The change regressed namespace creation in pre-defined regions that > > relied on 2M alignment but a workaround was provided in the form of a > > sysfs attribute, named 'align', that could be adjusted to a non-default > > alignment value. > > > > However, the sysfs attribute's store function returned an error (-ENXIO) > > when userspace attempted to change the alignment of a region that had no > > mappings. This affected 2M aligned regions of volatile memory that were > > defined in a device tree using "pmem-region" and created by the > > of_pmem_region_driver, since those regions do not contain mappings > > (ndr_mappings is 0). > > > > Allow userspace to set the align attribute on pre-existing regions that > > do not have mappings so that namespaces can still be within those > > regions, despite not being aligned to 16M. > > > > Fixes: 2522afb86a8c ("libnvdimm/region: Introduce an 'align' attribute") > > Signed-off-by: Tyler Hicks > > --- > > drivers/nvdimm/region_devs.c | 33 ++++++++++++++++++--------------- > > 1 file changed, 18 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c > > index ef23119db574..09cff8aa6b40 100644 > > --- a/drivers/nvdimm/region_devs.c > > +++ b/drivers/nvdimm/region_devs.c > > @@ -545,29 +545,32 @@ static ssize_t align_store(struct device *dev, > > struct device_attribute *attr, const char *buf, size_t len) > > { > > struct nd_region *nd_region = to_nd_region(dev); > > - unsigned long val, dpa; > > - u32 remainder; > > + unsigned long val; > > int rc; > > > > rc = kstrtoul(buf, 0, &val); > > if (rc) > > return rc; > > > > - if (!nd_region->ndr_mappings) > > - return -ENXIO; > > - > > - /* > > - * Ensure space-align is evenly divisible by the region > > - * interleave-width because the kernel typically has no facility > > - * to determine which DIMM(s), dimm-physical-addresses, would > > - * contribute to the tail capacity in system-physical-address > > - * space for the namespace. > > - */ > > - dpa = div_u64_rem(val, nd_region->ndr_mappings, &remainder); > > - if (!is_power_of_2(dpa) || dpa < PAGE_SIZE > > - || val > region_size(nd_region) || remainder) > > + if (val > region_size(nd_region)) > > return -EINVAL; > > > > + if (nd_region->ndr_mappings) { > > + unsigned long dpa; > > + u32 remainder; > > + > > + /* > > + * Ensure space-align is evenly divisible by the region > > + * interleave-width because the kernel typically has no facility > > + * to determine which DIMM(s), dimm-physical-addresses, would > > + * contribute to the tail capacity in system-physical-address > > + * space for the namespace. > > + */ > > + dpa = div_u64_rem(val, nd_region->ndr_mappings, &remainder); > > + if (!is_power_of_2(dpa) || dpa < PAGE_SIZE || remainder) > > + return -EINVAL; > > + } > > We still want > > else { > > if (!is_power_of_2(val) || val < PAGE_SIZE) > return -EINVAL? Yes, very good point. I'll send out a v2 that ensures val is a power of 2 and at least page size. Tyler > > } > > + > > /* > > * Given that space allocation consults this value multiple > > * times ensure it does not change for the duration of the > > -- > > 2.25.1 > > _______________________________________________ > > Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org > > To unsubscribe send an email to linux-nvdimm-leave@lists.01.org > _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org