Commit 5e24c9fd authored by Dan Williams's avatar Dan Williams

libnvdimm, dax: fix alignment validation

Testing the dax-device autodetect support revealed a probe failure with
the following result:

    dax0.1: bad offset: 0x8200000 dax disabled

The original pfn-device implementation inferred the alignment from
ilog2(offset), now that the alignment is explicit the is_power_of_2()
needs replacing with a real sanity check against the recorded alignment.
Otherwise the alignment check is useless in the implicit case and only
the minimum size of the offset matters.

This self-consistency check is further validated by the probe path that
will re-check that the offset is large enough to contain all the
metadata required to enable the device.

Cc: <>
Signed-off-by: default avatarDan Williams <>
parent c5ed9268
......@@ -416,6 +416,8 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
return -ENODEV;
if (nd_pfn->align == 0)
nd_pfn->align = le32_to_cpu(pfn_sb->align);
if (nd_pfn->align > nvdimm_namespace_capacity(ndns)) {
dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
nd_pfn->align, nvdimm_namespace_capacity(ndns));
......@@ -436,8 +438,8 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
return -EBUSY;
nd_pfn->align = le32_to_cpu(pfn_sb->align);
if (!is_power_of_2(offset) || offset < PAGE_SIZE) {
if ((nd_pfn->align && !IS_ALIGNED(offset, nd_pfn->align))
|| !IS_ALIGNED(offset, PAGE_SIZE)) {
dev_err(&nd_pfn->dev, "bad offset: %#llx dax disabled\n",
return -ENXIO;
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