[PATCH -mm] vmscan: make mapped executable pages the first class citizen

[Wu Fengguang <fengguang.wu@intel.com>]

Introduce AS_EXEC to mark executables and their linked libraries, and to
protect their referenced active pages from being deactivated.

CC: Elladan <elladan@eskimo.com>
CC: Nick Piggin <npiggin@suse.de>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Christoph Lameter <cl@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 include/linux/pagemap.h |    1 +
 mm/mmap.c               |    2 ++
 mm/nommu.c              |    2 ++
 mm/vmscan.c             |   35 +++++++++++++++++++++++++++++++++--
 4 files changed, 38 insertions(+), 2 deletions(-)

--- linux.orig/include/linux/pagemap.h
+++ linux/include/linux/pagemap.h
@@ -25,6 +25,7 @@ enum mapping_flags {
 #ifdef CONFIG_UNEVICTABLE_LRU
 	AS_UNEVICTABLE	= __GFP_BITS_SHIFT + 3,	/* e.g., ramdisk, SHM_LOCK */
 #endif
+	AS_EXEC		= __GFP_BITS_SHIFT + 4,	/* mapped PROT_EXEC somewhere */
 };
 
 static inline void mapping_set_error(struct address_space *mapping, int error)
--- linux.orig/mm/mmap.c
+++ linux/mm/mmap.c
@@ -1194,6 +1194,8 @@ munmap_back:
 			goto unmap_and_free_vma;
 		if (vm_flags & VM_EXECUTABLE)
 			added_exe_file_vma(mm);
+		if (vm_flags & VM_EXEC)
+			set_bit(AS_EXEC, &file->f_mapping->flags);
 	} else if (vm_flags & VM_SHARED) {
 		error = shmem_zero_setup(vma);
 		if (error)
--- linux.orig/mm/nommu.c
+++ linux/mm/nommu.c
@@ -1224,6 +1224,8 @@ unsigned long do_mmap_pgoff(struct file 
 			added_exe_file_vma(current->mm);
 			vma->vm_mm = current->mm;
 		}
+		if (vm_flags & VM_EXEC)
+			set_bit(AS_EXEC, &file->f_mapping->flags);
 	}
 
 	down_write(&nommu_region_sem);
--- linux.orig/mm/vmscan.c
+++ linux/mm/vmscan.c
@@ -1230,6 +1230,7 @@ static void shrink_active_list(unsigned 
 	unsigned long pgmoved;
 	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
+	LIST_HEAD(l_active);
 	LIST_HEAD(l_inactive);
 	struct page *page;
 	struct pagevec pvec;
@@ -1269,8 +1270,15 @@ 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)) {
+			struct address_space *mapping = page_mapping(page);
+
 			pgmoved++;
+			if (mapping && test_bit(AS_EXEC, &mapping->flags)) {
+				list_add(&page->lru, &l_active);
+				continue;
+			}
+		}
 
 		list_add(&page->lru, &l_inactive);
 	}
@@ -1279,7 +1287,6 @@ static void shrink_active_list(unsigned 
 	 * Move the pages to the [file or anon] inactive list.
 	 */
 	pagevec_init(&pvec, 1);
-	lru = LRU_BASE + file * LRU_FILE;
 
 	spin_lock_irq(&zone->lru_lock);
 	/*
@@ -1291,6 +1298,7 @@ static void shrink_active_list(unsigned 
 	reclaim_stat->recent_rotated[!!file] += pgmoved;
 
 	pgmoved = 0;  /* count pages moved to inactive list */
+	lru = LRU_BASE + file * LRU_FILE;
 	while (!list_empty(&l_inactive)) {
 		page = lru_to_page(&l_inactive);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);
@@ -1313,6 +1321,29 @@ static void shrink_active_list(unsigned 
 	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
 	__count_vm_events(PGDEACTIVATE, pgmoved);
+
+	pgmoved = 0;  /* count pages moved back to active list */
+	lru = LRU_ACTIVE + file * LRU_FILE;
+	while (!list_empty(&l_active)) {
+		page = lru_to_page(&l_active);
+		prefetchw_prev_lru_page(page, &l_active, flags);
+		VM_BUG_ON(PageLRU(page));
+		SetPageLRU(page);
+		VM_BUG_ON(!PageActive(page));
+
+		list_move(&page->lru, &zone->lru[lru].list);
+		mem_cgroup_add_lru_list(page, lru);
+		pgmoved++;
+		if (!pagevec_add(&pvec, page)) {
+			spin_unlock_irq(&zone->lru_lock);
+			if (buffer_heads_over_limit)
+				pagevec_strip(&pvec);
+			__pagevec_release(&pvec);
+			spin_lock_irq(&zone->lru_lock);
+		}
+	}
+	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
+
 	spin_unlock_irq(&zone->lru_lock);
 	if (buffer_heads_over_limit)
 		pagevec_strip(&pvec);

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