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Subject[PATCH 4/4] ksm: add support for scanning procsses that were not modifided to use ksm
Date
This patch add merge_pid and unmerge_pid fields into /sys/kernel/mm/ksm
this feild allow merging memory of any application in the system,
just run:
echo pid_num > /sys/kernel/mm/ksm/merge_pid - and memory will be merged.

This patch add MMF_VM_MERGEALL flag into the mm flags, this flags mean that
all the vmas inside this mm_struct are mergeable by ksm.

Signed-off-by: Izik Eidus <ieidus@redhat.com>
---
include/linux/sched.h | 1 +
mm/ksm.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7dc786a..c23af0c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -440,6 +440,7 @@ extern int get_dumpable(struct mm_struct *mm);
#endif

#define MMF_VM_MERGEABLE 9
+#define MMF_VM_MERGEALL 10

struct sighand_struct {
atomic_t count;
diff --git a/mm/ksm.c b/mm/ksm.c
index 901cce3..5bb42d8 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -479,7 +479,10 @@ static int try_to_merge_one_page(struct mm_struct *mm,
unsigned long page_addr_in_vma;
pte_t orig_pte, *orig_ptep;

- if(!(vma->vm_flags & VM_MERGEABLE))
+
+
+ if(!(vma->vm_flags & VM_MERGEABLE) &&
+ !test_bit(MMF_VM_MERGEALL, &mm->flags))
goto out;

if (!PageAnon(oldpage))
@@ -1213,7 +1216,8 @@ static struct mm_slot *get_next_mmlist(struct list_head *cur,
cur = cur->next;
while (cur != &init_mm.mmlist) {
mm = list_entry(cur, struct mm_struct, mmlist);
- if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
+ if (test_bit(MMF_VM_MERGEABLE, &mm->flags) ||
+ test_bit(MMF_VM_MERGEALL, &mm->flags)) {
mm_slot = get_mm_slot(mm);
if (unlikely(atomic_read(&mm->mm_users) == 1)) {
if (mm_slot)
@@ -1245,6 +1249,7 @@ static struct mm_slot *get_next_mmlist(struct list_head *cur,
int used_slot = 0;
int used_rmap = 0;
int ret = -EAGAIN;
+ int merge_all;

pre_alloc_rmap_item = alloc_rmap_item();
if (!pre_alloc_rmap_item)
@@ -1287,8 +1292,10 @@ static struct mm_slot *get_next_mmlist(struct list_head *cur,
ksm_scan->addr_index += PAGE_SIZE;

again:
+ merge_all = test_bit(MMF_VM_MERGEALL, &slot->mm->flags);
+
vma = find_vma(slot->mm, ksm_scan->addr_index);
- if (vma && vma->vm_flags & VM_MERGEABLE) {
+ if (vma && (vma->vm_flags & VM_MERGEABLE || merge_all)) {
if (ksm_scan->addr_index < vma->vm_start)
ksm_scan->addr_index = vma->vm_start;
up_read(&slot->mm->mmap_sem);
@@ -1304,7 +1311,7 @@ again:
ret = 0;
goto out_free;
} else {
- while (vma && !(vma->vm_flags & VM_MERGEABLE))
+ while (vma && (!(vma->vm_flags & VM_MERGEABLE) && !merge_all))
vma = vma->vm_next;

if (vma) {
@@ -1455,6 +1462,99 @@ int ksm_scan_thread(void *nothing)
static struct kobj_attribute _name##_attr = \
__ATTR(_name, 0644, _name##_show, _name##_store)

+static ssize_t merge_pid_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ unsigned int usecs;
+
+ down_read(&ksm_thread_lock);
+ usecs = ksm_thread_sleep;
+ up_read(&ksm_thread_lock);
+
+ return sprintf(buf, "\n");
+}
+
+static ssize_t merge_pid_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct task_struct *task;
+ struct mm_struct *mm = NULL;
+ unsigned long pid;
+ int err;
+
+ err = strict_strtoul(buf, 10, &pid);
+ if (err)
+ return 0;
+
+ read_lock(&tasklist_lock);
+ task = find_task_by_vpid(pid);
+ if (task)
+ mm = get_task_mm(task);
+ read_unlock(&tasklist_lock);
+
+ if (mm) {
+ down_write(&mm->mmap_sem);
+ set_bit(MMF_VM_MERGEALL, &mm->flags);
+ up_write(&mm->mmap_sem);
+
+ spin_lock(&mmlist_lock);
+ if (unlikely(list_empty(&mm->mmlist)))
+ list_add(&mm->mmlist, &init_mm.mmlist);
+ if (unlikely(!(mmlist_mask & MMLIST_KSM)))
+ mmlist_mask |= MMLIST_KSM;
+ spin_unlock(&mmlist_lock);
+
+ mmput(mm);
+ }
+
+ return count;
+}
+KSM_ATTR(merge_pid);
+
+static ssize_t unmerge_pid_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ unsigned int usecs;
+
+ down_read(&ksm_thread_lock);
+ usecs = ksm_thread_sleep;
+ up_read(&ksm_thread_lock);
+
+ return sprintf(buf, "\n");
+}
+
+static ssize_t unmerge_pid_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct task_struct *task;
+ struct mm_struct *mm = NULL;
+ unsigned long pid;
+ int err;
+
+ err = strict_strtoul(buf, 10, &pid);
+ if (err)
+ return 0;
+
+ read_lock(&tasklist_lock);
+ task = find_task_by_vpid(pid);
+ if (task)
+ mm = get_task_mm(task);
+ read_unlock(&tasklist_lock);
+
+ if (mm) {
+ down_write(&mm->mmap_sem);
+ clear_bit(MMF_VM_MERGEALL, &mm->flags);
+ up_write(&mm->mmap_sem);
+
+ mmput(mm);
+ }
+
+ return count;
+}
+KSM_ATTR(unmerge_pid);
+
static ssize_t sleep_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
@@ -1605,6 +1705,8 @@ static ssize_t max_kernel_pages_show(struct kobject *kobj,
KSM_ATTR(max_kernel_pages);

static struct attribute *ksm_attrs[] = {
+ &merge_pid_attr.attr,
+ &unmerge_pid_attr.attr,
&sleep_attr.attr,
&pages_to_scan_attr.attr,
&run_attr.attr,
--
1.5.6.5


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