From f218b6fc299829f8fdd9a579ec7b79ea4a1dbe8c Mon Sep 17 00:00:00 2001 From: Gerald Schaefer Date: Fri, 28 Sep 2012 10:19:22 +1000 Subject: [PATCH] thp, s390: disable thp for kvm host on s390 This patch is part of the architecture backend for thp on s390. It disables thp for kvm hosts, because there is no kvm host hugepage support so far. Existing thp mappings are split by follow_page() with FOLL_SPLIT, and future thp mappings are prevented by setting VM_NOHUGEPAGE in mm->def_flags. Signed-off-by: Gerald Schaefer Cc: Andrea Arcangeli Cc: Andi Kleen Cc: Hugh Dickins Cc: Hillf Danton Cc: Martin Schwidefsky Cc: Heiko Carstens Signed-off-by: Andrew Morton --- arch/s390/mm/pgtable.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 1ca371a06516..e86a523875eb 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -787,6 +787,30 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table) tlb_table_flush(tlb); } +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +void thp_split_vma(struct vm_area_struct *vma) +{ + unsigned long addr; + struct page *page; + + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { + page = follow_page(vma, addr, FOLL_SPLIT); + } +} + +void thp_split_mm(struct mm_struct *mm) +{ + struct vm_area_struct *vma = mm->mmap; + + while (vma != NULL) { + thp_split_vma(vma); + vma->vm_flags &= ~VM_HUGEPAGE; + vma->vm_flags |= VM_NOHUGEPAGE; + vma = vma->vm_next; + } +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + /* * switch on pgstes for its userspace process (for kvm) */ @@ -824,6 +848,12 @@ int s390_enable_sie(void) if (!mm) return -ENOMEM; +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + /* split thp mappings and disable thp for future mappings */ + thp_split_mm(mm); + mm->def_flags |= VM_NOHUGEPAGE; +#endif + /* Now lets check again if something happened */ task_lock(tsk); if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 || -- 2.39.5