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-rw-r--r--mm/rmap.c35
1 files changed, 22 insertions, 13 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index c81bedd7d52..98135dbd25b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -789,10 +789,9 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
* skipped over this mm) then we should reactivate it.
*/
if (!(flags & TTU_IGNORE_MLOCK)) {
- if (vma->vm_flags & VM_LOCKED) {
- ret = SWAP_MLOCK;
- goto out_unmap;
- }
+ if (vma->vm_flags & VM_LOCKED)
+ goto out_mlock;
+
if (TTU_ACTION(flags) == TTU_MUNLOCK)
goto out_unmap;
}
@@ -865,18 +864,28 @@ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
out_unmap:
pte_unmap_unlock(pte, ptl);
+out:
+ return ret;
- if (ret == SWAP_MLOCK) {
- ret = SWAP_AGAIN;
- if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
- if (vma->vm_flags & VM_LOCKED) {
- mlock_vma_page(page);
- ret = SWAP_MLOCK;
- }
- up_read(&vma->vm_mm->mmap_sem);
+out_mlock:
+ pte_unmap_unlock(pte, ptl);
+
+
+ /*
+ * We need mmap_sem locking, Otherwise VM_LOCKED check makes
+ * unstable result and race. Plus, We can't wait here because
+ * we now hold anon_vma->lock or mapping->i_mmap_lock.
+ * if trylock failed, the page remain in evictable lru and later
+ * vmscan could retry to move the page to unevictable lru if the
+ * page is actually mlocked.
+ */
+ if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
+ if (vma->vm_flags & VM_LOCKED) {
+ mlock_vma_page(page);
+ ret = SWAP_MLOCK;
}
+ up_read(&vma->vm_mm->mmap_sem);
}
-out:
return ret;
}