ksm: remove unswappable max_kernel_pages
Now that ksm pages are swappable, and the known holes plugged, remove
mention of unswappable kernel pages from KSM documentation and comments.
Remove the totalram_pages/4 initialization of max_kernel_pages. In fact,
remove max_kernel_pages altogether - we can reinstate it if removal turns
out to break someone's script; but if we later want to limit KSM's memory
usage, limiting the stable nodes would not be an effective approach.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/Kconfig b/mm/Kconfig
index d4b5fff..2310984 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -212,7 +212,7 @@
Enable Kernel Samepage Merging: KSM periodically scans those areas
of an application's address space that an app has advised may be
mergeable. When it finds pages of identical content, it replaces
- the many instances by a single resident page with that content, so
+ the many instances by a single page with that content, so
saving memory until one or another app needs to modify the content.
Recommended for use with KVM, or with other duplicative applications.
See Documentation/vm/ksm.txt for more information: KSM is inactive
diff --git a/mm/ksm.c b/mm/ksm.c
index d4c228a..56a0da1 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -179,9 +179,6 @@
/* The number of rmap_items in use: to calculate pages_volatile */
static unsigned long ksm_rmap_items;
-/* Limit on the number of unswappable pages used */
-static unsigned long ksm_max_kernel_pages;
-
/* Number of pages ksmd should scan in one batch */
static unsigned int ksm_thread_pages_to_scan = 100;
@@ -943,14 +940,6 @@
{
int err;
- /*
- * The number of nodes in the stable tree
- * is the number of kernel pages that we hold.
- */
- if (ksm_max_kernel_pages &&
- ksm_max_kernel_pages <= ksm_pages_shared)
- return NULL;
-
err = try_to_merge_with_ksm_page(rmap_item, page, NULL);
if (!err) {
err = try_to_merge_with_ksm_page(tree_rmap_item,
@@ -1850,8 +1839,8 @@
/*
* KSM_RUN_MERGE sets ksmd running, and 0 stops it running.
* KSM_RUN_UNMERGE stops it running and unmerges all rmap_items,
- * breaking COW to free the unswappable pages_shared (but leaves
- * mm_slots on the list for when ksmd may be set running again).
+ * breaking COW to free the pages_shared (but leaves mm_slots
+ * on the list for when ksmd may be set running again).
*/
mutex_lock(&ksm_thread_mutex);
@@ -1876,29 +1865,6 @@
}
KSM_ATTR(run);
-static ssize_t max_kernel_pages_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int err;
- unsigned long nr_pages;
-
- err = strict_strtoul(buf, 10, &nr_pages);
- if (err)
- return -EINVAL;
-
- ksm_max_kernel_pages = nr_pages;
-
- return count;
-}
-
-static ssize_t max_kernel_pages_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", ksm_max_kernel_pages);
-}
-KSM_ATTR(max_kernel_pages);
-
static ssize_t pages_shared_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -1948,7 +1914,6 @@
&sleep_millisecs_attr.attr,
&pages_to_scan_attr.attr,
&run_attr.attr,
- &max_kernel_pages_attr.attr,
&pages_shared_attr.attr,
&pages_sharing_attr.attr,
&pages_unshared_attr.attr,
@@ -1968,8 +1933,6 @@
struct task_struct *ksm_thread;
int err;
- ksm_max_kernel_pages = totalram_pages / 4;
-
err = ksm_slab_init();
if (err)
goto out;
