Patch "libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment" has been added to the 4.14-stable tree

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

libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment

to the 4.14-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-dax-fix-1gb-aligned-namespaces-vs-physical-misalignment.patch
and it can be found in the queue-4.14 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: Mon, 4 Dec 2017 14:07:43 -0800
Subject: libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment

From: Dan Williams <[email protected]>

commit 41fce90f26333c4fa82e8e43b9ace86c4e8a0120 upstream.

The following namespace configuration attempt:

    # ndctl create-namespace -e namespace0.0 -m devdax -a 1G -f
    libndctl: ndctl_dax_enable: dax0.1: failed to enable
      Error: namespace0.0: failed to enable

failed to reconfigure namespace: No such device or address

...fails when the backing memory range is not physically aligned to 1G:

    # cat /proc/iomem | grep Persistent
    210000000-30fffffff : Persistent Memory (legacy)

In the above example the 4G persistent memory range starts and ends on a 256MB boundary.

We handle this case correctly when needing to handle cases that violate section alignment (128MB) collisions against "System RAM", and we simply need to extend that padding/truncation for the 1GB alignment use case.

---
 drivers/nvdimm/pfn_devs.c |   15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

@@ -582,6 +582,12 @@ static struct vmem_altmap *__nvdimm_setu
 	return altmap;
 }
 
+static u64 phys_pmem_align_down(struct nd_pfn *nd_pfn, u64 phys)
+{
+	return min_t(u64, PHYS_SECTION_ALIGN_DOWN(phys),
+			ALIGN_DOWN(phys, nd_pfn->align));
+}
+
 static int nd_pfn_init(struct nd_pfn *nd_pfn)
 {
 	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;

@@ -637,13 +643,16 @@ static int nd_pfn_init(struct nd_pfn *nd
 	start = nsio->res.start;
 	size = PHYS_SECTION_ALIGN_UP(start + size) - start;
 	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
-				IORES_DESC_NONE) == REGION_MIXED) {
+				IORES_DESC_NONE) == REGION_MIXED
+			|| !IS_ALIGNED(start + resource_size(&nsio->res),
+				nd_pfn->align)) {
 		size = resource_size(&nsio->res);
-		end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start + size);
+		end_trunc = start + size - phys_pmem_align_down(nd_pfn,
+				start + size);
 	}
 
 	if (start_pad + end_trunc)
-		dev_info(&nd_pfn->dev, "%s section collision, truncate %d bytes\n",
+		dev_info(&nd_pfn->dev, "%s alignment collision, truncate %d bytes\n",
 				dev_name(&ndns->dev), start_pad + end_trunc);
 
 	/*

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

queue-4.14/libnvdimm-btt-fix-an-incompatibility-in-the-log-layout.patch queue-4.14/libnvdimm-pfn-fix-start_pad-handling-for-aligned-namespaces.patch queue-4.14/x86-ldt-prevent-ldt-inheritance-on-exec.patch queue-4.14/x86-ldt-rework-locking.patch queue-4.14/arch-mm-allow-arch_dup_mmap-to-fail.patch queue-4.14/libnvdimm-dax-fix-1gb-aligned-namespaces-vs-physical-misalignment.patch queue-4.14/acpi-nfit-fix-health-event-notification.patch