mmap: handle mlocked pages during map, remap, unmap

Originally by Nick Piggin <npiggin@suse.de>

Remove mlocked pages from the LRU using "unevictable infrastructure"
during mmap(), munmap(), mremap() and truncate().  Try to move back to
normal LRU lists on munmap() when last mlocked mapping removed.  Remove
PageMlocked() status when page truncated from file.

[akpm@linux-foundation.org: cleanup]
[kamezawa.hiroyu@jp.fujitsu.com: fix double unlock_page()]
[kosaki.motohiro@jp.fujitsu.com: split LRU: munlock rework]
[lee.schermerhorn@hp.com: mlock: fix __mlock_vma_pages_range comment block]
[akpm@linux-foundation.org: remove bogus kerneldoc token]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamewzawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 5 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index 7881638e4a12..7d12ca70ef7b 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -21,6 +21,8 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
+#include "internal.h"
+
 static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
                         unsigned long addr, pte_t *ptep)
 {
@@ -215,15 +217,31 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
                 spin_unlock(&mapping->i_mmap_lock);
         }
 
+        if (vma->vm_flags & VM_LOCKED) {
+                /*
+                 * drop PG_Mlocked flag for over-mapped range
+                 */
+                unsigned int saved_flags = vma->vm_flags;
+                munlock_vma_pages_range(vma, start, start + size);
+                vma->vm_flags = saved_flags;
+        }
+
         mmu_notifier_invalidate_range_start(mm, start, start + size);
         err = populate_range(mm, vma, start, size, pgoff);
         mmu_notifier_invalidate_range_end(mm, start, start + size);
         if (!err && !(flags & MAP_NONBLOCK)) {
-                if (unlikely(has_write_lock)) {
-                        downgrade_write(&mm->mmap_sem);
-                        has_write_lock = 0;
+                if (vma->vm_flags & VM_LOCKED) {
+                        /*
+                         * might be mapping previously unmapped range of file
+                         */
+                        mlock_vma_pages_range(vma, start, start + size);
+                } else {
+                        if (unlikely(has_write_lock)) {
+                                downgrade_write(&mm->mmap_sem);
+                                has_write_lock = 0;
+                        }
+                        make_pages_present(start, start+size);
                 }
-                make_pages_present(start, start+size);
         }
 
         /*
@@ -240,4 +258,3 @@ out:
 
         return err;
 }
-