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Subject[PATCH 1/3] 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.

CC: Minchan Kim <minchan.kim@gmail.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
include/linux/rmap.h | 5 +++--
mm/rmap.c | 37 ++++++++++++++++++++++++++-----------
mm/vmscan.c | 7 +++++--
3 files changed, 34 insertions(+), 15 deletions(-)

--- linux.orig/include/linux/rmap.h
+++ linux/include/linux/rmap.h
@@ -83,7 +83,8 @@ static inline void page_dup_rmap(struct
/*
* Called from mm/vmscan.c to handle paging out
*/
-int page_referenced(struct page *, int is_locked, struct mem_cgroup *cnt);
+int page_referenced(struct page *, int is_locked,
+ struct mem_cgroup *cnt, unsigned long *vm_flags);
int try_to_unmap(struct page *, int ignore_refs);

/*
@@ -128,7 +129,7 @@ int page_wrprotect(struct page *page, in
#define anon_vma_prepare(vma) (0)
#define anon_vma_link(vma) do {} while (0)

-#define page_referenced(page,l,cnt) TestClearPageReferenced(page)
+#define page_referenced(page, locked, cnt, flags) TestClearPageReferenced(page)
#define try_to_unmap(page, refs) SWAP_FAIL

static inline int page_mkclean(struct page *page)
--- linux.orig/mm/rmap.c
+++ linux/mm/rmap.c
@@ -333,7 +333,9 @@ static int page_mapped_in_vma(struct pag
* 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 p
*/
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 p
* 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
*
* 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 p
* 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 p
*/
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 p
* @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
*
* 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);
}
}
--- linux.orig/mm/vmscan.c
+++ linux/mm/vmscan.c
@@ -598,6 +598,7 @@ static unsigned long shrink_page_list(st
struct pagevec freed_pvec;
int pgactivate = 0;
unsigned long nr_reclaimed = 0;
+ unsigned long vm_flags;

cond_resched();

@@ -648,7 +649,8 @@ static unsigned long shrink_page_list(st
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))
@@ -1229,6 +1231,7 @@ static void shrink_active_list(unsigned
{
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;
@@ -1269,7 +1272,7 @@ static void shrink_active_list(unsigned

/* 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);
--



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