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Subject[PATCH v2] mm: cleanup some useless code
Date
From: Kaitao Cheng <pilgrimtao@gmail.com>

Compound pages handling in mem_cgroup_migrate is more convoluted than
necessary. The state is duplicated in compound variable and the same
could be achieved by PageTransHuge check which is trivial and
hpage_nr_pages is already PageTransHuge aware.

It is much simpler to just use hpage_nr_pages for nr_pages and replace
the local variable by PageTransHuge check directly

Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
Change in v2:
Update commit message

mm/memcontrol.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bc01423277c5..870284d3ee9d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6678,7 +6678,6 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
{
struct mem_cgroup *memcg;
unsigned int nr_pages;
- bool compound;
unsigned long flags;

VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
@@ -6700,8 +6699,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
return;

/* Force-charge the new page. The old one will be freed soon */
- compound = PageTransHuge(newpage);
- nr_pages = compound ? hpage_nr_pages(newpage) : 1;
+ nr_pages = hpage_nr_pages(newpage);

page_counter_charge(&memcg->memory, nr_pages);
if (do_memsw_account())
@@ -6711,7 +6709,8 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
commit_charge(newpage, memcg, false);

local_irq_save(flags);
- mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages);
+ mem_cgroup_charge_statistics(memcg, newpage, PageTransHuge(newpage),
+ nr_pages);
memcg_check_events(memcg, newpage);
local_irq_restore(flags);
}
--
2.20.1
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