The patch titled
Subject: mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary
has been added to the -mm tree. Its filename is
mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary.patch
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------------------------------------------------------
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;
}
_
Subject: Subject: mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
linux-next.patch
memcg-update-maintainers.patch
mm-page-writebackc-make-determine_dirtyable_memory-static-again.patch
vmscan-promote-shared-file-mapped-pages.patch
vmscan-activate-executable-pages-after-first-usage.patch
mm-do-not-stall-in-synchronous-compaction-for-thp-allocations.patch
mm-do-not-stall-in-synchronous-compaction-for-thp-allocations-v3.patch
vmscan-add-task-name-to-warn_scan_unevictable-messages.patch
cgroups-add-res_counter_write_u64-api.patch
cgroups-new-resource-counter-inheritance-api.patch
cgroups-add-previous-cgroup-in-can_attach_task-attach_task-callbacks.patch
cgroups-new-cancel_attach_task-subsystem-callback.patch
cgroups-ability-to-stop-res-charge-propagation-on-bounded-ancestor.patch
cgroups-add-res-counter-common-ancestor-searching.patch
res_counter-allow-charge-failure-pointer-to-be-null.patch
cgroups-pull-up-res-counter-charge-failure-interpretation-to-caller.patch
cgroups-allow-subsystems-to-cancel-a-fork.patch
cgroups-add-a-task-counter-subsystem.patch
memcg-make-mem_cgroup_split_huge_fixup-more-efficient.patch
memcg-fix-pgpgin-pgpgout-documentation.patch
mm-page_cgroup-check-page_cgroup-arrays-in-lookup_page_cgroup-only-when-necessary.patch
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