mm/rmap: use rmap_walk() in try_to_unmap()
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().
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 97bf8f0..b3263cb 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1179,15 +1179,18 @@
/*
* 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)
@@ -1513,6 +1516,11 @@
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
@@ -1558,7 +1566,7 @@
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;
}
@@ -1592,7 +1600,7 @@
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;
}
@@ -1614,6 +1622,11 @@
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
@@ -1631,16 +1644,29 @@
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;
@@ -1683,7 +1709,6 @@
anon_vma_free(anon_vma);
}
-#ifdef CONFIG_MIGRATION
static struct anon_vma *rmap_walk_anon_lock(struct page *page,
struct rmap_walk_control *rwc)
{
@@ -1785,7 +1810,6 @@
else
return rmap_walk_file(page, rwc);
}
-#endif /* CONFIG_MIGRATION */
#ifdef CONFIG_HUGETLB_PAGE
/*