On Thu, Sep 20, 2018 at 06:25:29PM +0100, Catalin Marinas wrote:

On Wed, Jun 06, 2018 at 12:31:21PM +0530, Chintan Pandya wrote:

quoted

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 8ae5d7a..65f8627 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c

@@ -45,6 +45,7 @@
 #include <asm/memblock.h>
 #include <asm/mmu_context.h>
 #include <asm/ptdump.h>
+#include <asm/tlbflush.h>
 
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)

@@ -977,12 +978,51 @@ int pmd_clear_huge(pmd_t *pmdp)
 	return 1;
 }
 
-int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
 {
-	return pud_none(*pud);
+	pte_t *table;
+	pmd_t pmd;
+
+	pmd = READ_ONCE(*pmdp);
+
+	/* No-op for empty entry and WARN_ON for valid entry */
+	if (!pmd_present(pmd) || !pmd_table(pmd)) {
+		VM_WARN_ON(!pmd_table(pmd));
+		return 1;
+	}

What's this VM_WARN_ON supposed to do here? If the pmd is 0, we trigger
it all the time. Did you actually mean something like:

		VM_WARN_ON(!pmd_none(pmd));

or pmd_present(pmd)?

Since the comment mentions empty entry, I'd rather make it explicit:

	if (pmd_none(pmd) || !pmd_table(pmd))
		VM_WARN_ON(!pmd_none(pmd));
		return 1;
	}

Ignore this, fixed in -rc4 (fac880c7d074 "arm64: fix erroneous warnings
in page freeing functions").

-- 
Catalin