Re: linux-next: build failure after merge of the akpm-current tree

Aneesh Kumar K.V
2015-05-14T15:10:02Z

Stephen Rothwell <sfr@canb.auug.org.au> writes:

> Hi Andrew,
>
> After merging the akpm-current tree, today's linux-next build (sparc
> defconfig) failed like this:
>
> In file included from arch/sparc/include/asm/pgtable_32.h:437:0,
> from arch/sparc/include/asm/pgtable.h:6,
> from include/linux/mm.h:53,
> from include/linux/ring_buffer.h:5,
> from include/linux/ftrace_event.h:5,
> from include/trace/syscall.h:6,
> from include/linux/syscalls.h:81,
> from init/initramfs.c:19:
> include/asm-generic/pgtable.h: In function 'pmdp_collapse_flush':
> include/asm-generic/pgtable.h:211:2: error: implicit declaration of function '__pmd' [-Werror=implicit-function-declaration]
> return __pmd(0);
> ^
> include/asm-generic/pgtable.h:211:2: error: incompatible types when returning type 'int' but 'pmd_t' was expected
>
> Caused by commit b0593c13d7f6 ("mm/thp: split out pmd collapse/flush
> into separate functions").
>
> sparc 32 has no __pmd(). I applied this temporary fix for today just
> to get it building:

The change in question is

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 39f1d6a2b04d..9e200e55a52b 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -189,6 +189,26 @@ extern void pmdp_splitting_flush(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#endif

+#ifndef pmdp_collapse_flush
+#define pmdp_collapse_flush pmdp_collapse_flush
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
+ unsigned long address,
+ pmd_t *pmdp)
+{
+ return pmdp_clear_flush(vma, address, pmdp);
+}
+#else
+static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
+ unsigned long address,
+ pmd_t *pmdp)
+{
+ BUILD_BUG();
+ return __pmd(0);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable);

This also introduced warnings for frv and m68k. May be we should drop
the #else part and let the build fail during linking ? ie, do

+#ifndef pmdp_collapse_flush
+#define pmdp_collapse_flush pmdp_collapse_flush
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
+ unsigned long address,
+ pmd_t *pmdp)
+{
+ return pmdp_clear_flush(vma, address, pmdp);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif

-aneesh