fsi: Add regmap and refactor sbefifo

Merge series from Eddie James <eajames@linux.ibm.com>:

The SBEFIFO hardware can now be attached over a new I2C endpoint interface
called the I2C Responder (I2CR). In order to use the existing SBEFIFO
driver, add a regmap driver for the FSI bus and an endpoint driver for the
I2CR. Then, refactor the SBEFIFO and OCC drivers to clean up and use the
new regmap driver or the I2CR interface.

This branch just has the regmap change so it can be shared with the FSI
code.

1 files changed, 16 insertions, 4 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1cc4a5f4791e..811d19b5c4f6 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2206,9 +2206,12 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 				entry = pte_wrprotect(entry);
 			if (!young)
 				entry = pte_mkold(entry);
-			/* NOTE: this may set soft-dirty too on some archs */
-			if (dirty)
-				entry = pte_mkdirty(entry);
+			/*
+			 * NOTE: we don't do pte_mkdirty when dirty==true
+			 * because it breaks sparc64 which can sigsegv
+			 * random process.  Need to revisit when we figure
+			 * out what is special with sparc64.
+			 */
 			if (soft_dirty)
 				entry = pte_mksoft_dirty(entry);
 			if (uffd_wp)
@@ -2455,7 +2458,16 @@ static void __split_huge_page_tail(struct page *head, int tail,
 			page_tail);
 	page_tail->mapping = head->mapping;
 	page_tail->index = head->index + tail;
-	page_tail->private = 0;
+
+	/*
+	 * page->private should not be set in tail pages with the exception
+	 * of swap cache pages that store the swp_entry_t in tail pages.
+	 * Fix up and warn once if private is unexpectedly set.
+	 */
+	if (!folio_test_swapcache(page_folio(head))) {
+		VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail);
+		page_tail->private = 0;
+	}
 
 	/* Page flags must be visible before we make the page non-compound. */
 	smp_wmb();