Patch "libnvdimm, pfn: fix 'npfns' vs section alignment" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

libnvdimm, pfn: fix 'npfns' vs section alignment

to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
libnvdimm-pfn-fix-npfns-vs-section-alignment.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dan Williams <[email protected]>
Date: Thu, 4 May 2017 19:54:42 -0700
Subject: libnvdimm, pfn: fix 'npfns' vs section alignment

From: Dan Williams <[email protected]>

commit d5483feda85a8f39ee2e940e279547c686aac30c upstream.

Fix failures to create namespaces due to the vmem_altmap not advertising enough free space to store the memmap.

 WARNING: CPU: 15 PID: 8022 at arch/x86/mm/init_64.c:656 arch_add_memory+0xde/0xf0
 [..]
 Call Trace:
  dump_stack+0x63/0x83
  __warn+0xcb/0xf0
  warn_slowpath_null+0x1d/0x20
  arch_add_memory+0xde/0xf0
  devm_memremap_pages+0x244/0x440
  pmem_attach_disk+0x37e/0x490 [nd_pmem]
  nd_pmem_probe+0x7e/0xa0 [nd_pmem]
  nvdimm_bus_probe+0x71/0x120 [libnvdimm]
  driver_probe_device+0x2bb/0x460
  bind_store+0x114/0x160
  drv_attr_store+0x25/0x30

In commit 658922e57b84 "libnvdimm, pfn: fix memmap reservation sizing" we arranged for the capacity to be allocated, but failed to also update the 'npfns' parameter. This leads to cases where there is enough capacity reserved to hold all the allocated sections, but vmemmap_populate_hugepages() still encounters -ENOMEM from altmap_alloc_block_buf().

This fix is a stop-gap until we can teach the core memory hotplug implementation to permit sub-section hotplug.

---
 drivers/nvdimm/pfn_devs.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -538,7 +538,8 @@ static struct vmem_altmap *__nvdimm_setu
 		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
 		altmap = NULL;
 	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
-		nd_pfn->npfns = (resource_size(res) - offset) / PAGE_SIZE;
+		nd_pfn->npfns = PFN_SECTION_ALIGN_UP((resource_size(res)
+					- offset) / PAGE_SIZE);
 		if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
 			dev_info(&nd_pfn->dev,
 					"number of pfns truncated from %lld to %ld\n",

@@ -625,7 +626,8 @@ static int nd_pfn_init(struct nd_pfn *nd
 	 */
 	start += start_pad;
 	size = resource_size(&nsio->res);
-	npfns = (size - start_pad - end_trunc - SZ_8K) / SZ_4K;
+	npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)
+			/ PAGE_SIZE);
 	if (nd_pfn->mode == PFN_MODE_PMEM) {
 		/*
 		 * vmemmap_populate_hugepages() allocates the memmap array in

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/libnvdimm-fix-nvdimm_bus_lock-vs-device_lock-ordering.patch queue-4.10/x86-pmem-fix-cache-flushing-for-iovec-write-8-bytes.patch queue-4.10/dax-prevent-invalidation-of-mapped-dax-entries.patch queue-4.10/libnvdimm-region-fix-flush-hint-detection-crash.patch queue-4.10/libnvdimm-pfn-fix-npfns-vs-section-alignment.patch queue-4.10/libnvdimm-pmem-fix-a-null-pointer-bug-in-nd_pmem_notify.patch queue-4.10/device-dax-fix-cdev-leak.patch queue-4.10/device-dax-fix-sysfs-attribute-deadlock.patch queue-4.10/mm-fix-data-corruption-due-to-stale-mmap-reads.patch