From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail1.bemta23.messagelabs.com (mail1.bemta23.messagelabs.com [67.219.246.213]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 134B621A07A80 for ; Tue, 11 Sep 2018 01:50:02 -0700 (PDT) From: Ocean HY1 He Subject: RE: [External] Re: [PATCH 0/3] libnvdimm: reset seeds for next namespace creation Date: Tue, 11 Sep 2018 08:49:47 +0000 Message-ID: References: <1536560508-24564-1-git-send-email-oceanhehy@gmail.com> In-Reply-To: Content-Language: en-US MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams , Ocean He Cc: linux-nvdimm , Linux Kernel Mailing List , "zwisler@kernel.org" List-ID: > -----Original Message----- > From: Dan Williams > Sent: Tuesday, September 11, 2018 8:51 AM > To: Ocean He > Cc: zwisler@kernel.org; Vishal L Verma ; Dave Jiang > ; linux-nvdimm ; Linux > Kernel Mailing List ; Ocean HY1 He > > Subject: [External] Re: [PATCH 0/3] libnvdimm: reset seeds for next > namespace creation > > On Sun, Sep 9, 2018 at 11:21 PM, Ocean He wrote: > > From: Ocean He > > > > When pmem namespaces created are smaller than section size twice, the > > second creation would fail and meanwhile there is a kernel call trace > > which comes from commit 15d36fecd0bdc7510b70 ("mm: disallow mappings > that > > conflict for devm_memremap_pages()"). > > ------------[ cut here ]------------ > > nd_pmem pfn1.1: Conflicting mapping in same section > > WARNING: CPU: 84 PID: 51974 at kernel/memremap.c:194 > devm_memremap_pages+0x4a0/0x4e0 > > CPU: 84 PID: 51974 Comm: ndctl Kdump: loaded Tainted: G W E 4.19.0- > rc2-23-default+ #27 > > RIP: 0010:devm_memremap_pages+0x4a0/0x4e0 > > Call Trace: > > pmem_attach_disk+0x3ab/0x581 [nd_pmem] > > nvdimm_bus_probe+0x69/0x150 [libnvdimm] > > really_probe+0x262/0x3d0 > > driver_probe_device+0x60/0x120 > > bind_store+0x102/0x190 > > kernfs_fop_write+0x105/0x180 > > __vfs_write+0x36/0x1a0 > > ? common_file_perm+0x47/0x130 > > ? security_file_permission+0x2c/0xb0 > > vfs_write+0xad/0x1a0 > > ksys_write+0x52/0xc0 > > do_syscall_64+0x5b/0x180 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > > Here is an example (section size is 128MB) based on kernel 4.19-rc2. > > # ndctl create-namespace -r region1 -s 100m -t pmem -m fsdax > > { > > "dev":"namespace1.0", > > "mode":"fsdax", > > "map":"dev", > > "size":"96.00 MiB (100.66 MB)", > > "uuid":"ef9a0556-a610-40b5-8c71-43991765a2cc", > > "raw_uuid":"177b22e2-b7e8-482f-a063-2b8de876d979", > > "sector_size":512, > > "blockdev":"pmem1", > > "numa_node":1 > > } > > # ndctl create-namespace -r region1 -s 100m -t pmem -m fsdax > > libndctl: ndctl_pfn_enable: pfn1.1: failed to enable > > Error: namespace1.1: failed to enable > > failed to create namespace: No such device or address > > > > When above second creation failure occurs, the expectation is to destroy > > namespace1.0 to create a new namespace which size is aligned with section > > size. However, both namespace seed and pfn seed have been consumed, > the > > new namespace creation still fails. > > # ndctl destroy-namespace namespace1.0 -f > > destroyed 1 namespace > > # ndctl create-namespace -r region1 -s 128m -t pmem -m fsdax > > failed to create namespace: Device or resource busy > > > > To ensure pfn_seed/dax_seed and namespace_seed are always ready for > next > > namespace creation, this patch set enables seed detach and reset. Back to > > the example, the new namespace creation never fails if this patch set > > applied. > > # ndctl destroy-namespace namespace1.0 -f > > destroyed 1 namespace > > # ndctl create-namespace -r region1 -s 128m -t pmem -m fsdax > > { > > "dev":"namespace1.0", > > "mode":"fsdax", > > "map":"dev", > > "size":"124.00 MiB (130.02 MB)", > > "uuid":"0d0e7506-d108-4a88-824a-edef26fd0399", > > "raw_uuid":"efeb9647-12f5-44cd-8a52-2f3a0d14589a", > > "sector_size":512, > > "blockdev":"pmem1", > > "numa_node":1 > > } > > # ndctl create-namespace -r region1 -s 128m -t pmem -m fsdax > > { > > "dev":"namespace1.1", > > "mode":"fsdax", > > "map":"dev", > > "size":130023424, > > "uuid":"689828dc-8779-434d-8e93-0406d4e1e536", > > "raw_uuid":"d86e1025-c224-48b6-b2a7-6ccef152d5fd", > > "sector_size":512, > > "blockdev":"pmem1.1", > > "numa_node":1 > > } > > > > The mode devdax (-m devdax) has the same issue, this patch set could > > cover it. > > This is good analysis, but I believe this is better fixed / handled in > ndctl directly. This is just one of a few reasons that namespace > creation can fail, and it should be ndctl's job to recover from failed > creation. The kernel only provides the mechanism the policy of what to > do with errors and interrupted namespace creation is up to userspace. > Well, thanks for your review. I just send out the patch of ndctl for this issue, please help to review again. Many thanks! https://lists.01.org/pipermail/linux-nvdimm/2018-September/017778.html Ocean. > Also, in the future, the plan is to allow namespaces smaller than a > section size which will fix this particular failing condition > properly. I am interesting that what minimal size is allowed for namespace creation. I need this to guide the NVDIMM enablement on Lenovo ThinkSystem Servers. I see function nvdimm_namespace_common_probe return error if size is less than ND_MIN_NAMESPACE_SIZE(equals to PAGE_SIZE). size = nvdimm_namespace_capacity(ndns); if (size < ND_MIN_NAMESPACE_SIZE) { dev_dbg(&ndns->dev, "%pa, too small must be at least %#x\n", &size, ND_MIN_NAMESPACE_SIZE); return ERR_PTR(-ENODEV); } I also see function nd_namespace_store return error if size is less than SZ_16M. if (__nvdimm_namespace_capacity(ndns) < SZ_16M) { dev_dbg(dev, "%s too small to host\n", name); len = -ENXIO; goto out_attach; } Ocean. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm