---

yaml
---
r: 332379
b: refs/heads/master
c: 75077af
h: refs/heads/master
i:
  332377: 017d6a0
  332375: e12d898
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8e72033f2a489b6c98c4e3c7cc281b1afd6cb85c
+refs/heads/master: 75077afbec1ac89178c1542b23a70d0f960b0aaf

trunk/arch/s390/include/asm/pgtable.h

@@ -347,6 +347,8 @@ extern struct page *vmemmap;
 
 #define _SEGMENT_ENTRY_LARGE	0x400	/* STE-format control, large page   */
 #define _SEGMENT_ENTRY_CO	0x100	/* change-recording override   */
+#define _SEGMENT_ENTRY_SPLIT_BIT 0	/* THP splitting bit number */
+#define _SEGMENT_ENTRY_SPLIT	(1UL << _SEGMENT_ENTRY_SPLIT_BIT)
 
 /* Page status table bits for virtualization */
 #define RCP_ACC_BITS	0xf000000000000000UL
@@ -506,6 +508,10 @@ static inline int pmd_bad(pmd_t pmd)
 	return (pmd_val(pmd) & mask) != _SEGMENT_ENTRY;
 }
 
+#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+extern void pmdp_splitting_flush(struct vm_area_struct *vma,
+				 unsigned long addr, pmd_t *pmdp);
+
 static inline int pte_none(pte_t pte)
 {
 	return (pte_val(pte) & _PAGE_INVALID) && !(pte_val(pte) & _PAGE_SWT);
@@ -1159,6 +1165,13 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
 #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
 #define pte_unmap(pte) do { } while (0)
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_trans_splitting(pmd_t pmd)
+{
+	return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
 /*
  * 31 bit swap entry format:
  * A page-table entry has some bits we have to treat in a special way.

trunk/arch/s390/mm/gup.c

@@ -115,7 +115,16 @@ static inline int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr,
 		pmd = *pmdp;
 		barrier();
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
+		/*
+		 * The pmd_trans_splitting() check below explains why
+		 * pmdp_splitting_flush() has to serialize with
+		 * smp_call_function() against our disabled IRQs, to stop
+		 * this gup-fast code from running while we set the
+		 * splitting bit in the pmd. Returning zero will take
+		 * the slow path that will call wait_split_huge_page()
+		 * if the pmd is still in splitting state.
+		 */
+		if (pmd_none(pmd) || pmd_trans_splitting(pmd))
 			return 0;
 		if (unlikely(pmd_huge(pmd))) {
 			if (!gup_huge_pmd(pmdp, pmd, addr, next,

trunk/arch/s390/mm/pgtable.c

@@ -866,3 +866,21 @@ bool kernel_page_present(struct page *page)
 	return cc == 0;
 }
 #endif /* CONFIG_HIBERNATION && CONFIG_DEBUG_PAGEALLOC */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static void pmdp_splitting_flush_sync(void *arg)
+{
+	/* Simply deliver the interrupt */
+}
+
+void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
+			  pmd_t *pmdp)
+{
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	if (!test_and_set_bit(_SEGMENT_ENTRY_SPLIT_BIT,
+			      (unsigned long *) pmdp)) {
+		/* need to serialize against gup-fast (IRQ disabled) */
+		smp_call_function(pmdp_splitting_flush_sync, NULL, 1);
+	}
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */