It allow for user to control process of marking new vma as VM_MERGEABLE
Create new sysfs interface /sys/kernel/mm/ksm/mark_new_vma
1 - enabled - mark new allocated vma as VM_MERGEABLE and add it to ksm queue
0 - disable it
Signed-off-by: Timofey Titovets <nefelim...@gmail.com>
---
include/linux/ksm.h | 10 +++++++++-
mm/ksm.c | 39 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 47 insertions(+), 2 deletions(-)
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index c3fff64..deb60fc 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -76,6 +76,12 @@ struct page *ksm_might_need_to_copy(struct page *page,
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
void ksm_migrate_page(struct page *newpage, struct page *oldpage);
+
+/* Mark new vma as mergeable */
+#define ALLOW 1
+#define DENY 0
+extern unsigned mark_new_vma __read_mostly;
+
/*
* Allow to mark new vma as VM_MERGEABLE
*/
@@ -84,6 +90,8 @@ void ksm_migrate_page(struct page *newpage, struct page
*oldpage);
#endif
static inline void ksm_vm_flags_mod(unsigned long *vm_flags)
{
+ if (!mark_new_vma)
+ return;
if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE |
VM_PFNMAP | VM_IO | VM_DONTEXPAND |
VM_HUGETLB | VM_NONLINEAR | VM_MIXEDMAP | VM_SAO) )
@@ -94,7 +102,7 @@ static inline void ksm_vm_flags_mod(unsigned long *vm_flags)
static inline void ksm_vma_add_new(struct vm_area_struct *vma)
{
struct mm_struct *mm = vma->vm_mm;
- if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
+ if (mark_new_vma && !test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
__ksm_enter(mm);
}
}
diff --git a/mm/ksm.c b/mm/ksm.c
index 6b2e337..7bfb616 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -223,6 +223,12 @@ static unsigned int ksm_thread_pages_to_scan = 100;
/* Milliseconds ksmd should sleep between batches */
static unsigned int ksm_thread_sleep_millisecs = 20;
+/* Mark new vma as mergeable */
+#ifndef CONFIG_KSM_MARK_NEW_VMA
+#define CONFIG_KSM_MARK_NEW_VMA DENY
+#endif
+unsigned mark_new_vma = CONFIG_KSM_MARK_NEW_VMA;
+
#ifdef CONFIG_NUMA
/* Zeroed when merging across nodes is not allowed */
static unsigned int ksm_merge_across_nodes = 1;
@@ -2127,6 +2133,34 @@ static ssize_t pages_to_scan_store(struct kobject *kobj,
}
KSM_ATTR(pages_to_scan);
+static ssize_t mark_new_vma_show(struct kobject *kobj, struct kobj_attribute
*attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", mark_new_vma);
+}
+static ssize_t mark_new_vma_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long flags;
+
+ err = kstrtoul(buf, 10, &flags);
+ if (err || flags > UINT_MAX || flags > ALLOW)
+ return -EINVAL;
+
+ /*
+ * ALLOW = 1 - sets allow for mark new vma as
+ * VM_MERGEABLE and adding it to ksm
+ * DENY = 0 - disable it
+ */
+ if (mark_new_vma != flags) {
+ mark_new_vma = flags;
+ }
+ return count;
+}
+KSM_ATTR(mark_new_vma);
+
static ssize_t run_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
@@ -2287,6 +2321,7 @@ static struct attribute *ksm_attrs[] = {
&pages_unshared_attr.attr,
&pages_volatile_attr.attr,
&full_scans_attr.attr,
+ &mark_new_vma_attr.attr,
#ifdef CONFIG_NUMA
&merge_across_nodes_attr.attr,
#endif
@@ -2323,7 +2358,9 @@ static int __init ksm_init(void)
goto out_free;
}
#else
- ksm_run = KSM_RUN_MERGE; /* no way for user to start it */
+ /* no way for user to start it */
+ mark_new_vma = ALLOW;
+ ksm_run = KSM_RUN_MERGE;
#endif /* CONFIG_SYSFS */
--
2.1.3
--
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