New subject: Patch "libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment" has been added to the 4.9-stable tree

23 Feb 2018

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.
Cc: stable@vger.kernel.org
Fixes: 315c562536c4 ("libnvdimm, pfn: add 'align' attribute...")
Reported-and-tested-by: Jane Chu jane.chu@oracle.com
Signed-off-by: Dan Williams dan.j.williams@intel.com
---
 drivers/nvdimm/pfn_devs.c |   15 ++++++++++++---
 include/linux/kernel.h    |    1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 42abdd2391c9..d6aa59ca68b9 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -563,6 +563,12 @@ static struct vmem_altmap *__nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
    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;
@@ -618,13 +624,16 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
    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);
/*
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index bc6ed52a39b9..61054f12be7c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -46,6 +46,7 @@
 #define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
#define ALIGN(x, a)		__ALIGN_KERNEL((x), (a))
+#define ALIGN_DOWN(x, a)	__ALIGN_KERNEL((x) - ((a) - 1), (a))
 #define __ALIGN_MASK(x, mask)	__ALIGN_KERNEL_MASK((x), (mask))
 #define PTR_ALIGN(p, a)		((typeof(p))ALIGN((unsigned long)(p), (a)))
 #define IS_ALIGNED(x, a)		(((x) & ((typeof(x))(a) - 1)) == 0)

    

[4.9-stable PATCH 08/11] libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment