[PATCH v2] define vmemmap before pfn_to_page calls

[PATCH v2] define vmemmap before pfn_to_page calls

[David Abdurachmanov]

pfn_to_page & page_to_pfn depend on vmemmap being available before the calls
if kernel is configured with CONFIG_SPARSEMEM_VMEMMAP=y. This was caused
by NOMMU changes which moved vmemmap definition bellow functions definitions
calling pfn_to_page & page_to_pfn.

Noticed while compiled 5.5-rc2 kernel for Fedora/RISCV.

v2:
- Add a comment for vmemmap in source

Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
Fixes: 6bd33e1ece52 ("riscv: add nommu support")
Reviewed-by: Anup Patel <anup@brainfault.org>
---
 arch/riscv/include/asm/pgtable.h | 38 ++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7ff0ed4f292e..36ae01761352 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -90,6 +90,27 @@ extern pgd_t swapper_pg_dir[];
 #define __S110	PAGE_SHARED_EXEC
 #define __S111	PAGE_SHARED_EXEC
 
+#define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
+#define VMALLOC_END      (PAGE_OFFSET - 1)
+#define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
+
+/*
+ * Roughly size the vmemmap space to be large enough to fit enough
+ * struct pages to map half the virtual address space. Then
+ * position vmemmap directly below the VMALLOC region.
+ */
+#define VMEMMAP_SHIFT \
+	(CONFIG_VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)
+#define VMEMMAP_SIZE	BIT(VMEMMAP_SHIFT)
+#define VMEMMAP_END	(VMALLOC_START - 1)
+#define VMEMMAP_START	(VMALLOC_START - VMEMMAP_SIZE)
+
+/*
+ * Define vmemmap for pfn_to_page & page_to_pfn calls. Needed if kernel
+ * is configured with CONFIG_SPARSEMEM_VMEMMAP enabled.
+ */
+#define vmemmap		((struct page *)VMEMMAP_START)
+
 static inline int pmd_present(pmd_t pmd)
 {
 	return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE));
@@ -400,23 +421,6 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
 
-#define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
-#define VMALLOC_END      (PAGE_OFFSET - 1)
-#define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
-
-/*
- * Roughly size the vmemmap space to be large enough to fit enough
- * struct pages to map half the virtual address space. Then
- * position vmemmap directly below the VMALLOC region.
- */
-#define VMEMMAP_SHIFT \
-	(CONFIG_VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)
-#define VMEMMAP_SIZE	BIT(VMEMMAP_SHIFT)
-#define VMEMMAP_END	(VMALLOC_START - 1)
-#define VMEMMAP_START	(VMALLOC_START - VMEMMAP_SIZE)
-
-#define vmemmap		((struct page *)VMEMMAP_START)
-
 #define PCI_IO_SIZE      SZ_16M
 #define PCI_IO_END       VMEMMAP_START
 #define PCI_IO_START     (PCI_IO_END - PCI_IO_SIZE)
-- 
2.24.1

Re: [PATCH v2] define vmemmap before pfn_to_page calls

[Paul Walmsley]

On Wed, 18 Dec 2019, David Abdurachmanov wrote:

> pfn_to_page & page_to_pfn depend on vmemmap being available before the calls
> if kernel is configured with CONFIG_SPARSEMEM_VMEMMAP=y. This was caused
> by NOMMU changes which moved vmemmap definition bellow functions definitions
> calling pfn_to_page & page_to_pfn.
> 
> Noticed while compiled 5.5-rc2 kernel for Fedora/RISCV.
> 
> v2:
> - Add a comment for vmemmap in source
> 
> Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
> Fixes: 6bd33e1ece52 ("riscv: add nommu support")
> Reviewed-by: Anup Patel <anup@brainfault.org>

This looks like it was due to my error when resolving the merge conflicts, 
not Christoph's.  Queued for v5.5-rc, thanks David.


- Paul