lkml.org 
[lkml]   [2012]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC v2 PATCH 6/7] thp, s390: disable thp for kvm host on s390
Date
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 <gerald.schaefer@de.ibm.com>
---
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 3168fbd..7846072 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 ||
--
1.7.11.5


\
 
 \ /
  Last update: 2012-08-29 18:01    [W:0.133 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site