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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2015-02-11 15:25:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-11 17:06:02 -0800
commit81422f29c5f4fb968023f465218c3d978c133ceb (patch)
tree87ee41d4351d2ecd1a8affeb563e3e8aca2961d2 /mm/page_alloc.c
parent6e9f0d582dde095d971a3c6ce4685a218a0eac8e (diff)
downloadop-kernel-dev-81422f29c5f4fb968023f465218c3d978c133ceb.zip
op-kernel-dev-81422f29c5f4fb968023f465218c3d978c133ceb.tar.gz
mm: more checks on free_pages_prepare() for tail pages
Although it was not called, destroy_compound_page() did some potentially useful checks. Let's re-introduce them in free_pages_prepare(), where they can be actually triggered when CONFIG_DEBUG_VM=y. compound_order() assert is already in free_pages_prepare(). We have few checks for tail pages left. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c27
1 files changed, 23 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 12d55b8..0081228 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -764,21 +764,40 @@ static void free_one_page(struct zone *zone,
spin_unlock(&zone->lock);
}
+static int free_tail_pages_check(struct page *head_page, struct page *page)
+{
+ if (!IS_ENABLED(CONFIG_DEBUG_VM))
+ return 0;
+ if (unlikely(!PageTail(page))) {
+ bad_page(page, "PageTail not set", 0);
+ return 1;
+ }
+ if (unlikely(page->first_page != head_page)) {
+ bad_page(page, "first_page not consistent", 0);
+ return 1;
+ }
+ return 0;
+}
+
static bool free_pages_prepare(struct page *page, unsigned int order)
{
- int i;
- int bad = 0;
+ bool compound = PageCompound(page);
+ int i, bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
- VM_BUG_ON_PAGE(PageHead(page) && compound_order(page) != order, page);
+ VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
if (PageAnon(page))
page->mapping = NULL;
- for (i = 0; i < (1 << order); i++)
+ bad += free_pages_check(page);
+ for (i = 1; i < (1 << order); i++) {
+ if (compound)
+ bad += free_tail_pages_check(page, page + i);
bad += free_pages_check(page + i);
+ }
if (bad)
return false;
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