vmscan: report vm_flags in page_referenced()

Collect vma->vm_flags of the VMAs that actually referenced the page.

This is preparing for more informed reclaim heuristics, eg.  to protect
executable file pages more aggressively.  For now only the VM_EXEC bit
will be used by the caller.

Thanks to Johannes, Peter and Minchan for all the good tips.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 31 insertions, 13 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 316c9d6930ad..c9ccc1a72dc3 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -333,7 +333,9 @@ static int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
  * repeatedly from either page_referenced_anon or page_referenced_file.
  */
 static int page_referenced_one(struct page *page,
-        struct vm_area_struct *vma, unsigned int *mapcount)
+                               struct vm_area_struct *vma,
+                               unsigned int *mapcount,
+                               unsigned long *vm_flags)
 {
         struct mm_struct *mm = vma->vm_mm;
         unsigned long address;
@@ -381,11 +383,14 @@ out_unmap:
         (*mapcount)--;
         pte_unmap_unlock(pte, ptl);
 out:
+        if (referenced)
+                *vm_flags |= vma->vm_flags;
         return referenced;
 }
 
 static int page_referenced_anon(struct page *page,
-                                struct mem_cgroup *mem_cont)
+                                struct mem_cgroup *mem_cont,
+                                unsigned long *vm_flags)
 {
         unsigned int mapcount;
         struct anon_vma *anon_vma;
@@ -405,7 +410,8 @@ static int page_referenced_anon(struct page *page,
                  */
                 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
                         continue;
-                referenced += page_referenced_one(page, vma, &mapcount);
+                referenced += page_referenced_one(page, vma,
+                                                  &mapcount, vm_flags);
                 if (!mapcount)
                         break;
         }
@@ -418,6 +424,7 @@ static int page_referenced_anon(struct page *page,
  * page_referenced_file - referenced check for object-based rmap
  * @page: the page we're checking references on.
  * @mem_cont: target memory controller
+ * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
  *
  * For an object-based mapped page, find all the places it is mapped and
  * check/clear the referenced flag.  This is done by following the page->mapping
@@ -427,7 +434,8 @@ static int page_referenced_anon(struct page *page,
  * This function is only called from page_referenced for object-based pages.
  */
 static int page_referenced_file(struct page *page,
-                                struct mem_cgroup *mem_cont)
+                                struct mem_cgroup *mem_cont,
+                                unsigned long *vm_flags)
 {
         unsigned int mapcount;
         struct address_space *mapping = page->mapping;
@@ -467,7 +475,8 @@ static int page_referenced_file(struct page *page,
                  */
                 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
                         continue;
-                referenced += page_referenced_one(page, vma, &mapcount);
+                referenced += page_referenced_one(page, vma,
+                                                  &mapcount, vm_flags);
                 if (!mapcount)
                         break;
         }
@@ -481,29 +490,35 @@ static int page_referenced_file(struct page *page,
  * @page: the page to test
  * @is_locked: caller holds lock on the page
  * @mem_cont: target memory controller
+ * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
  *
  * Quick test_and_clear_referenced for all mappings to a page,
  * returns the number of ptes which referenced the page.
  */
-int page_referenced(struct page *page, int is_locked,
-                        struct mem_cgroup *mem_cont)
+int page_referenced(struct page *page,
+                    int is_locked,
+                    struct mem_cgroup *mem_cont,
+                    unsigned long *vm_flags)
 {
         int referenced = 0;
 
         if (TestClearPageReferenced(page))
                 referenced++;
 
+        *vm_flags = 0;
         if (page_mapped(page) && page->mapping) {
                 if (PageAnon(page))
-                        referenced += page_referenced_anon(page, mem_cont);
+                        referenced += page_referenced_anon(page, mem_cont,
+                                                                vm_flags);
                 else if (is_locked)
-                        referenced += page_referenced_file(page, mem_cont);
+                        referenced += page_referenced_file(page, mem_cont,
+                                                                vm_flags);
                 else if (!trylock_page(page))
                         referenced++;
                 else {
                         if (page->mapping)
-                                referenced +=
-                                        page_referenced_file(page, mem_cont);
+                                referenced += page_referenced_file(page,
+                                                        mem_cont, vm_flags);
                         unlock_page(page);
                 }
         }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 52339dd7bf85..6be2068f61c8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -577,6 +577,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
         struct pagevec freed_pvec;
         int pgactivate = 0;
         unsigned long nr_reclaimed = 0;
+        unsigned long vm_flags;
 
         cond_resched();
 
@@ -627,7 +628,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                                 goto keep_locked;
                 }
 
-                referenced = page_referenced(page, 1, sc->mem_cgroup);
+                referenced = page_referenced(page, 1,
+                                                sc->mem_cgroup, &vm_flags);
                 /* In active use or really unfreeable?  Activate it. */
                 if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
                                         referenced && page_mapping_inuse(page))
@@ -1208,6 +1210,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 {
         unsigned long pgmoved;
         unsigned long pgscanned;
+        unsigned long vm_flags;
         LIST_HEAD(l_hold);      /* The pages which were snipped off */
         LIST_HEAD(l_inactive);
         struct page *page;
@@ -1248,7 +1251,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 
                 /* page_referenced clears PageReferenced */
                 if (page_mapping_inuse(page) &&
-                    page_referenced(page, 0, sc->mem_cgroup))
+                    page_referenced(page, 0, sc->mem_cgroup, &vm_flags))
                         pgmoved++;
 
                 list_add(&page->lru, &l_inactive);