From: Kaitao Cheng <[email protected]>
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 <[email protected]>
Acked-by: Michal Hocko <[email protected]>
---
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
chengkaitao writes:
>Subject: Re: [PATCH v2] mm: cleanup some useless code
Can you please write a more descriptive commit title? Seeing this in the commit
history tells the reader nothing, "code" could mean anything from a state
machine to a boolean, and "cleanup" could mean anything from some complex
refactoring to something trivial like this, and right now I have to look and
see the individual commit. This patch is really just deduplication of effort.
Perhaps:
mm, memcg: Don't check PageTransHuge before calling hpage_nr_pages
>It is much simpler to just use hpage_nr_pages for nr_pages and replace
>the local variable by PageTransHuge check directly
Heh, calling it "much" simpler seems a bit excessive. I mean, the code is just
as readable in both cases, but if it's going to go in, then that's fine. Any
merge conflict should be trivial enough to fix.
>Signed-off-by: Kaitao Cheng <[email protected]>
>Acked-by: Michal Hocko <[email protected]>
I'm indifferent to this patch, but after the title change:
Acked-by: Chris Down <[email protected]>