Now, we have an infrastructure in rmap_walk() to handle difference
from variants of rmap traversing functions.
So, just use it in try_to_unmap().
In this patch, I change following things.
1. enable rmap_walk() if !CONFIG_MIGRATION.
2. mechanical change to use rmap_walk() in try_to_unmap().
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 616aa4d..2462458 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -190,7 +190,7 @@ int page_referenced_one(struct page *, struct vm_area_struct *,
int try_to_unmap(struct page *, enum ttu_flags flags);
int try_to_unmap_one(struct page *, struct vm_area_struct *,
- unsigned long address, enum ttu_flags flags);
+ unsigned long address, void *arg);
/*
* Called from mm/filemap_xip.c to unmap empty zero page
@@ -256,9 +256,6 @@ struct rmap_walk_control {
bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
};
-/*
- * Called by migrate.c to remove migration ptes, but might be used more later.
- */
int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
#else /* !CONFIG_MMU */
diff --git a/mm/ksm.c b/mm/ksm.c
index 91b8cb3..6b4baa9 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1982,7 +1982,7 @@ again:
continue;
ret = try_to_unmap_one(page, vma,
- rmap_item->address, flags);
+ rmap_item->address, (void *)flags);
if (ret != SWAP_AGAIN || !page_mapped(page)) {
anon_vma_unlock_read(anon_vma);
goto out;
@@ -1996,7 +1996,6 @@ out:
return ret;
}
-#ifdef CONFIG_MIGRATION
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
{
struct stable_node *stable_node;
@@ -2054,6 +2053,7 @@ out:
return ret;
}
+#ifdef CONFIG_MIGRATION
void ksm_migrate_page(struct page *newpage, struct page *oldpage)
{
struct stable_node *stable_node;
diff --git a/mm/rmap.c b/mm/rmap.c
index a292707..d34fa0e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1175,15 +1175,18 @@ out:
/*
* Subfunctions of try_to_unmap: try_to_unmap_one called
* repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file.
+ *
+ * @arg: enum ttu_flags will be passed to this argument
*/
int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
- unsigned long address, enum ttu_flags flags)
+ unsigned long address, void *arg)
{
struct mm_struct *mm = vma->vm_mm;
pte_t *pte;
pte_t pteval;
spinlock_t *ptl;
int ret = SWAP_AGAIN;
+ enum ttu_flags flags = (enum ttu_flags)arg;
pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
@@ -1509,6 +1512,11 @@ bool is_vma_temporary_stack(struct vm_area_struct *vma)
return false;
}
+static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
+{
+ return is_vma_temporary_stack(vma);
+}
+
/**
* try_to_unmap_anon - unmap or unlock anonymous page using the object-based
* rmap method
@@ -1554,7 +1562,7 @@ static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
continue;
address = vma_address(page, vma);
- ret = try_to_unmap_one(page, vma, address, flags);
+ ret = try_to_unmap_one(page, vma, address, (void *)flags);
if (ret != SWAP_AGAIN || !page_mapped(page))
break;
}
@@ -1588,7 +1596,7 @@ static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
mutex_lock(&mapping->i_mmap_mutex);
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
unsigned long address = vma_address(page, vma);
- ret = try_to_unmap_one(page, vma, address, flags);
+ ret = try_to_unmap_one(page, vma, address, (void *)flags);
if (ret != SWAP_AGAIN || !page_mapped(page))
goto out;
}
@@ -1610,6 +1618,11 @@ out:
return ret;
}
+static int page_not_mapped(struct page *page)
+{
+ return !page_mapped(page);
+};
+
/**
* try_to_unmap - try to remove all page table mappings to a page
* @page: the page to get unmapped
@@ -1627,16 +1640,29 @@ out:
int try_to_unmap(struct page *page, enum ttu_flags flags)
{
int ret;
+ struct rmap_walk_control rwc = {
+ .rmap_one = try_to_unmap_one,
+ .arg = (void *)flags,
+ .done = page_not_mapped,
+ .file_nonlinear = try_to_unmap_nonlinear,
+ .anon_lock = page_lock_anon_vma_read,
+ };
- BUG_ON(!PageLocked(page));
VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
- if (unlikely(PageKsm(page)))
- ret = try_to_unmap_ksm(page, flags);
- else if (PageAnon(page))
- ret = try_to_unmap_anon(page, flags);
- else
- ret = try_to_unmap_file(page, flags);
+ /*
+ * During exec, a temporary VMA is setup and later moved.
+ * The VMA is moved under the anon_vma lock but not the
+ * page tables leading to a race where migration cannot
+ * find the migration ptes. Rather than increasing the
+ * locking requirements of exec(), migration skips
+ * temporary VMAs until after exec() completes.
+ */
+ if (flags & TTU_MIGRATION && !PageKsm(page) && PageAnon(page))
+ rwc.invalid_vma = invalid_migration_vma;
+
+ ret = rmap_walk(page, &rwc);
+
if (ret != SWAP_MLOCK && !page_mapped(page))
ret = SWAP_SUCCESS;
return ret;
@@ -1679,7 +1705,6 @@ void __put_anon_vma(struct anon_vma *anon_vma)
anon_vma_free(anon_vma);
}
-#ifdef CONFIG_MIGRATION
static struct anon_vma *rmap_walk_anon_lock(struct page *page,
struct rmap_walk_control *rwc)
{
@@ -1781,7 +1806,6 @@ int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
else
return rmap_walk_file(page, rwc);
}
-#endif /* CONFIG_MIGRATION */
#ifdef CONFIG_HUGETLB_PAGE
/*
--
1.7.9.5
--
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