On 2/17/21 8:24 AM, Peter Xu wrote:

On Wed, Feb 10, 2021 at 04:03:18PM -0800, Mike Kravetz wrote:

quoted

Add interfaces to set and clear soft dirty in hugetlb ptes.  Make
hugetlb interfaces needed for /proc clear_refs available outside
hugetlb.c.

arch/s390 has it's own version of most routines in asm-generic/hugetlb.h,
so add new routines there as well.

Signed-off-by: Mike Kravetz <redacted>
---
 arch/s390/include/asm/hugetlb.h | 30 ++++++++++++++++++++++++++++++
 include/asm-generic/hugetlb.h   | 30 ++++++++++++++++++++++++++++++
 include/linux/hugetlb.h         |  1 +
 mm/hugetlb.c                    | 10 +---------
 4 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 60f9241e5e4a..b7d26248fb1c 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h

@@ -105,6 +105,11 @@ static inline pte_t huge_pte_mkdirty(pte_t pte)
 	return pte_mkdirty(pte);
 }
 
+static inline pte_t huge_pte_mkyoung(pte_t pte)
+{
+	return pte_mkyoung(pte);
+}
+
 static inline pte_t huge_pte_wrprotect(pte_t pte)
 {
 	return pte_wrprotect(pte);

@@ -115,9 +120,34 @@ static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
 	return pte_modify(pte, newprot);
 }
 
+static inline bool huge_pte_soft_dirty(pte_t pte)
+{
+	return pte_soft_dirty(pte);
+}
+
+static inline pte_t huge_pte_clear_soft_dirty(pte_t pte)
+{
+	return pte_clear_soft_dirty(pte);
+}
+
+static inline pte_t huge_pte_swp_clear_soft_dirty(pte_t pte)
+{
+	return pte_swp_clear_soft_dirty(pte);
+}
+

Indeed asm/hugetlb.h of s390 didn't include asm-generic/hugetlb.h as what was
normally done by asm/hugetlb.h of other archs.  Do you know why it's special?
E.g. huge_pte_wrprotect() of s390 version is actually the same of the default
version.

When I looked at the huge_pte_wrprotect() I also see that there seems to have
no real user of __HAVE_ARCH_HUGE_PTE_WRPROTECT.  Not sure whether it can be
dropped.  My gut feeling is that s390 should also include asm-generic/hugetlb.h
but only redefine the helper only if necessary, since I see no point defining
the same helper multiple times.

I do not know why s390 is special in this way.  However, I did cc some s390
people and the list.  Perhaps they know?

quoted

 static inline bool gigantic_page_runtime_supported(void)
 {
 	return true;
 }
 
+#if !defined(__HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE) && !defined(MODULE)
+#include <asm/tlbflush.h>
+
+static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
+					unsigned long start, unsigned long end)
+{
+	flush_tlb_range(vma, start, end);
+}
+#endif

Similar question here, only ppc defined __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE, so
IIUC it means s390 should simply use the default version, and it'll be great if
we don't need to redefine it here.

Actually, your patch "mm/hugetlb: Move flush_hugetlb_tlb_range() into
hugetlb.h" makes this change unnecessary.  But, the question about ppc
remains.
-- 
Mike Kravetz