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

[Rik van Riel]

The version of the patch to protect executable pages that is on
its way upstream.

-------- Original Message --------
Subject: [PATCH -mm] vmscan: make mapped executable pages the first 
class	citizen
Date: Thu, 7 May 2009 20:11:01 +0800
From: Wu Fengguang <fengguang.wu at intel.com>
To: Andrew Morton <akpm at linux-foundation.org>
CC: Peter Zijlstra <peterz at infradead.org>, Rik van Riel 
<riel at redhat.com>,        "linux-kernel at vger.kernel.org" 
<linux-kernel at vger.kernel.org>,        "tytso at mit.edu" <tytso at mit.edu>, 
        "linux-mm at kvack.org" <linux-mm at kvack.org>,        Elladan 
<elladan at eskimo.com>, Nick Piggin <npiggin at suse.de>,        Johannes 
Weiner <hannes at cmpxchg.org>,        Christoph Lameter 
<cl at linux-foundation.org>,        KOSAKI Motohiro 
<kosaki.motohiro at jp.fujitsu.com>
References: <20090430072057.GA4663 at eskimo.com> 
<20090430174536.d0f438dd.akpm at linux-foundation.org> 
<20090430205936.0f8b29fc at riellaptop.surriel.com> 
<20090430181340.6f07421d.akpm at linux-foundation.org> 
<20090430215034.4748e615 at riellaptop.surriel.com> 
<20090430195439.e02edc26.akpm at linux-foundation.org> 
<49FB01C1.6050204 at redhat.com> 
<20090501123541.7983a8ae.akpm at linux-foundation.org> 
<20090503031539.GC5702 at localhost> <1241432635.7620.4732.camel at twins>

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

CC: Elladan <elladan at eskimo.com>
CC: Nick Piggin <npiggin at suse.de>
CC: Johannes Weiner <hannes at cmpxchg.org>
CC: Christoph Lameter <cl at linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz at infradead.org>
Acked-by: Rik van Riel <riel at redhat.com>
Signed-off-by: Wu Fengguang <fengguang.wu at 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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