Re: [PATCH v8 18/24] mm: Provide speculative fault infrastructure

[Daniel Jordan]

Hi Laurent,

This series doesn't build for me[*] when CONFIG_TRANSPARENT_HUGEPAGE is unset.

The problem seems to be that the BUILD_BUG() version of pmd_same is called in pte_map_lock:

On 02/16/2018 10:25 AM, Laurent Dufour wrote:
> +static bool pte_map_lock(struct vm_fault *vmf)
> +{
...snip...
> +	if (!pmd_same(pmdval, vmf->orig_pmd))
> +		goto out;

Since SPF can now call pmd_same without THP, maybe the way to fix it is just

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 2cfa3075d148..e130692db24a 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -375,7 +375,8 @@ static inline int pte_unused(pte_t pte)
 #endif
 
 #ifndef __HAVE_ARCH_PMD_SAME
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
+    defined(CONFIG_SPECULATIVE_PAGE_FAULT)
 static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
 {
        return pmd_val(pmd_a) == pmd_val(pmd_b);

?

Daniel


[*]  The errors are:

In file included from /home/dmjordan/src/linux/include/linux/kernel.h:10:0,
                 from /home/dmjordan/src/linux/include/linux/list.h:9,
                 from /home/dmjordan/src/linux/include/linux/smp.h:12,
                 from /home/dmjordan/src/linux/include/linux/kernel_stat.h:5,
                 from /home/dmjordan/src/linux/mm/memory.c:41:
In function âpmd_same.isra.104â,
    inlined from âpte_map_lockâ at /home/dmjordan/src/linux/mm/memory.c:2380:7:
/home/dmjordan/src/linux/include/linux/compiler.h:324:38: error: call to â__compiletime_assert_391â declared with attribute error: BUILD_BUG failed
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
                                      ^
/home/dmjordan/src/linux/include/linux/compiler.h:304:4: note: in definition of macro â__compiletime_assertâ
    prefix ## suffix();    \
    ^~~~~~
/home/dmjordan/src/linux/include/linux/compiler.h:324:2: note: in expansion of macro â_compiletime_assertâ
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
  ^~~~~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/linux/build_bug.h:45:37: note: in expansion of macro âcompiletime_assertâ
 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^~~~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/linux/build_bug.h:79:21: note: in expansion of macro âBUILD_BUG_ON_MSGâ
 #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
                     ^~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/asm-generic/pgtable.h:391:2: note: in expansion of macro âBUILD_BUGâ
  BUILD_BUG();
  ^~~~~~~~~
  CC      block/elevator.o
  CC      crypto/crypto_wq.o
In function âpmd_same.isra.104â,
    inlined from âpte_spinlockâ at /home/dmjordan/src/linux/mm/memory.c:2326:7,
    inlined from âhandle_pte_faultâ at /home/dmjordan/src/linux/mm/memory.c:4181:7:
/home/dmjordan/src/linux/include/linux/compiler.h:324:38: error: call to â__compiletime_assert_391â declared with attribute error: BUILD_BUG failed
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
                                      ^
/home/dmjordan/src/linux/include/linux/compiler.h:304:4: note: in definition of macro â__compiletime_assertâ
    prefix ## suffix();    \
    ^~~~~~
/home/dmjordan/src/linux/include/linux/compiler.h:324:2: note: in expansion of macro â_compiletime_assertâ
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
  ^~~~~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/linux/build_bug.h:45:37: note: in expansion of macro âcompiletime_assertâ
 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^~~~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/linux/build_bug.h:79:21: note: in expansion of macro âBUILD_BUG_ON_MSGâ
 #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
                     ^~~~~~~~~~~~~~~~
/home/dmjordan/src/linux/include/asm-generic/pgtable.h:391:2: note: in expansion of macro âBUILD_BUGâ
  BUILD_BUG();
  ^~~~~~~~~
...
make[2]: *** [/home/dmjordan/src/linux/scripts/Makefile.build:316: mm/memory.o] Error 1
make[1]: *** [/home/dmjordan/src/linux/Makefile:1047: mm] Error 2