The patch titled
Subject: mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary
has been removed from the -mm tree. Its filename was
mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary
lookup_page_cgroup() is usually used only against pages that are used in
userspace.
The exception is the CONFIG_DEBUG_VM-only memcg check from the page
allocator: it can run on pages without page_cgroup descriptors allocated
when the pages are fed into the page allocator for the first time during
boot or memory hotplug.
Include the array check only when CONFIG_DEBUG_VM is set and save the
unnecessary check in production kernels.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_cgroup.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff -puN mm/page_cgroup.c~mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary mm/page_cgroup.c
--- a/mm/page_cgroup.c~mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary
+++ a/mm/page_cgroup.c
@@ -28,9 +28,16 @@ struct page_cgroup *lookup_page_cgroup(s
struct page_cgroup *base;
base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
+#ifdef CONFIG_DEBUG_VM
+ /*
+ * The sanity checks the page allocator does upon freeing a
+ * page can reach here before the page_cgroup arrays are
+ * allocated when feeding a range of pages to the allocator
+ * for the first time during bootup or memory hotplug.
+ */
if (unlikely(!base))
return NULL;
-
+#endif
offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
return base + offset;
}
@@ -85,9 +92,16 @@ struct page_cgroup *lookup_page_cgroup(s
{
unsigned long pfn = page_to_pfn(page);
struct mem_section *section = __pfn_to_section(pfn);
-
+#ifdef CONFIG_DEBUG_VM
+ /*
+ * The sanity checks the page allocator does upon freeing a
+ * page can reach here before the page_cgroup arrays are
+ * allocated when feeding a range of pages to the allocator
+ * for the first time during bootup or memory hotplug.
+ */
if (!section->page_cgroup)
return NULL;
+#endif
return section->page_cgroup + pfn;
}
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
origin.patch
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