diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 8e09c544d892..f798899338ed 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -103,6 +103,20 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 			flush_dcache_page(page);
 		}
 	} else {
+		/*
+		 * Note that we write the data both before and after
+		 * clearing poison.  The write before clear poison
+		 * handles situations where the latest written data is
+		 * preserved and the clear poison operation simply marks
+		 * the address range as valid without changing the data.
+		 * In this case application software can assume that an
+		 * interrupted write will either return the new good
+		 * data or an error.
+		 *
+		 * However, if pmem_clear_poison() leaves the data in an
+		 * indeterminate state we need to perform the write
+		 * after clear poison.
+		 */
 		flush_dcache_page(page);
 		memcpy_to_pmem(pmem_addr, mem + off, len);
 		if (unlikely(bad_pmem)) {
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
index ac6d872ce067..57d146fe44dd 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -72,6 +72,18 @@ static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
 }
 #endif
 
+static inline bool arch_has_pmem_api(void)
+{
+	return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
+}
+
+static inline int default_memcpy_from_pmem(void *dst, void __pmem const *src,
+		size_t size)
+{
+	memcpy(dst, (void __force *) src, size);
+	return 0;
+}
+
 /*
  * memcpy_from_pmem - read from persistent memory with error handling
  * @dst: destination buffer
@@ -83,12 +95,10 @@ static inline void arch_invalidate_pmem(void __pmem *addr, size_t size)
 static inline int memcpy_from_pmem(void *dst, void __pmem const *src,
 		size_t size)
 {
-	return arch_memcpy_from_pmem(dst, src, size);
-}
-
-static inline bool arch_has_pmem_api(void)
-{
-	return IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API);
+	if (arch_has_pmem_api())
+		return arch_memcpy_from_pmem(dst, src, size);
+	else
+		return default_memcpy_from_pmem(dst, src, size);
 }
 
 /**