This patch introduce fake VM_VRANGE flag in vma->vm_flags.
Actually, vma->vm_flags doesn't have such flag and it is just
used to detect a page is volatile page or not in page_referenced.
For it, page_referenced's vm_flags argument semantic is changed so that
caller should specify what kinds of flags he has interest.
It could make to avoid unnecessary volatile range lookup in
page_referenced_one.
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
include/linux/mm.h | 9 +++++++++
mm/rmap.c | 17 +++++++++++++----
mm/vmscan.c | 4 ++--
3 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8b6e55ee8855..3dec30154f96 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -103,6 +103,15 @@ extern unsigned int kobjsize(const void *objp);
#define VM_IO 0x00004000 /* Memory mapped I/O or similar */
/* Used by sys_madvise() */
+/*
+ * VM_VRANGE is rather special. Actually, vma->vm_flags doesn't have such flag.
+ * It is used to identify whether a page put on volatile range or not
+ * by page_referenced. So, if we are lack of new bit in vmflags, we could
+ * replace it with assembling exclusive flags.
+ *
+ * ex) VM_HUGEPAGE|VM_NOHUGEPAGE
+ */
+#define VM_VRANGE 0x00001000
#define VM_SEQ_READ 0x00008000 /* App will access data sequentially */
#define VM_RAND_READ 0x00010000 /* App will not benefit from clustered reads */
diff --git a/mm/rmap.c b/mm/rmap.c
index fd3ee7a54a13..9220f12deb93 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -57,6 +57,7 @@
#include <linux/migrate.h>
#include <linux/hugetlb.h>
#include <linux/backing-dev.h>
+#include <linux/vrange.h>
#include <asm/tlbflush.h>
@@ -685,7 +686,7 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
if (vma->vm_flags & VM_LOCKED) {
spin_unlock(&mm->page_table_lock);
*mapcount = 0; /* break early from loop */
- *vm_flags |= VM_LOCKED;
+ *vm_flags &= VM_LOCKED;
goto out;
}
@@ -708,7 +709,7 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
if (vma->vm_flags & VM_LOCKED) {
pte_unmap_unlock(pte, ptl);
*mapcount = 0; /* break early from loop */
- *vm_flags |= VM_LOCKED;
+ *vm_flags &= VM_LOCKED;
goto out;
}
@@ -724,12 +725,18 @@ int page_referenced_one(struct page *page, struct vm_area_struct *vma,
referenced++;
}
pte_unmap_unlock(pte, ptl);
+ if (*vm_flags & VM_VRANGE &&
+ vrange_addr_volatile(vma, address)) {
+ *mapcount = 0; /* break ealry from loop */
+ *vm_flags &= VM_VRANGE;
+ goto out;
+ }
}
(*mapcount)--;
if (referenced)
- *vm_flags |= vma->vm_flags;
+ *vm_flags &= vma->vm_flags;
out:
return referenced;
}
@@ -844,6 +851,9 @@ static int page_referenced_file(struct page *page,
*
* Quick test_and_clear_referenced for all mappings to a page,
* returns the number of ptes which referenced the page.
+ *
+ * NOTE: caller should pass interested flags in vm_flags to collect
+ * vma->vm_flags.
*/
int page_referenced(struct page *page,
int is_locked,
@@ -853,7 +863,6 @@ int page_referenced(struct page *page,
int referenced = 0;
int we_locked = 0;
- *vm_flags = 0;
if (page_mapped(page) && page_rmapping(page)) {
if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
we_locked = trylock_page(page);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eea668d9cff6..8bff386e65a0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -672,7 +672,7 @@ static enum page_references page_check_references(struct page *page,
struct scan_control *sc)
{
int referenced_ptes, referenced_page;
- unsigned long vm_flags;
+ unsigned long vm_flags = VM_EXEC|VM_LOCKED|VM_VRANGE;
referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
&vm_flags);
@@ -1619,7 +1619,6 @@ static void shrink_active_list(unsigned long nr_to_scan,
{
unsigned long nr_taken;
unsigned long nr_scanned;
- unsigned long vm_flags;
LIST_HEAD(l_hold); /* The pages which were snipped off */
LIST_HEAD(l_active);
LIST_HEAD(l_inactive);
@@ -1652,6 +1651,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
spin_unlock_irq(&zone->lru_lock);
while (!list_empty(&l_hold)) {
+ unsigned long vm_flags = VM_EXEC;
cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
--
1.7.9.5
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