* [PATCH v2] mm: cleanup some useless code
@ 2019-12-10 16:04 chengkaitao
2019-12-10 21:04 ` Chris Down
0 siblings, 1 reply; 2+ messages in thread
From: chengkaitao @ 2019-12-10 16:04 UTC (permalink / raw)
To: hannes
Cc: mhocko, vdavydov.dev, akpm, cgroups, linux-mm, linux-kernel,
smuchun, Kaitao Cheng, Michal Hocko
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] mm: cleanup some useless code
2019-12-10 16:04 [PATCH v2] mm: cleanup some useless code chengkaitao
@ 2019-12-10 21:04 ` Chris Down
0 siblings, 0 replies; 2+ messages in thread
From: Chris Down @ 2019-12-10 21:04 UTC (permalink / raw)
To: chengkaitao
Cc: hannes, mhocko, vdavydov.dev, akpm, cgroups, linux-mm,
linux-kernel, smuchun, Michal Hocko
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 <pilgrimtao@gmail.com>
>Acked-by: Michal Hocko <mhocko@suse.com>
I'm indifferent to this patch, but after the title change:
Acked-by: Chris Down <chris@chrisdown.name>
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