The patch titled
Subject: memcg: nano-optimize VM_BUG_ON in uncharge_page
has been added to the -mm tree. Its filename is
mm-memcg-avoid-page-count-check-for-zone-device-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-avoid-page-count-check-for-zone-device-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-avoid-page-count-check-for-zone-device-fix.patch
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From: Michal Hocko <mhocko@xxxxxxxx>
Subject: memcg: nano-optimize VM_BUG_ON in uncharge_page
Even though VM_BUG* is usually not compiled in there are systems which
enable CONFIG_DEBUG_VM by default. VM_BUG_ON_PAGE in uncharge_page is not
very optimal for the normal case. All pages should have counter==0 so
that is the first thing to check. is_zone_device_page is nicely noop if
ZONE_DEVICE is not compiled in and finally HW poison pages should be least
probable. So reorder the check to bail out as early as possible on normal
case.
Link: http://lkml.kernel.org/r/20170918063141.6coovns7cb45bfly@xxxxxxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN mm/memcontrol.c~mm-memcg-avoid-page-count-check-for-zone-device-fix mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcg-avoid-page-count-check-for-zone-device-fix
+++ a/mm/memcontrol.c
@@ -5658,8 +5658,8 @@ static void uncharge_batch(const struct
static void uncharge_page(struct page *page, struct uncharge_gather *ug)
{
VM_BUG_ON_PAGE(PageLRU(page), page);
- VM_BUG_ON_PAGE(!PageHWPoison(page) && !is_zone_device_page(page) &&
- page_count(page), page);
+ VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) &&
+ !PageHWPoison(page) , page);
if (!page->mem_cgroup)
return;
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-oom_reaper-skip-mm-structs-with-mmu-notifiers.patch
mm-memcg-remove-hotplug-locking-from-try_charge.patch
mm-memcg-avoid-page-count-check-for-zone-device-fix.patch
mm-memory_hotplug-add-scheduling-point-to-__add_pages.patch
mm-page_alloc-add-scheduling-point-to-memmap_init_zone.patch
memremap-add-scheduling-point-to-devm_memremap_pages.patch
mm-memory_hotplug-do-not-back-off-draining-pcp-free-pages-from-kworker-context.patch
mm-memory_hotplug-do-not-fail-offlining-too-early.patch
mm-memory_hotplug-remove-timeout-from-__offline_memory.patch
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