Hello Andrew,
here an incremental cleanup for this patch (it'd become
thp-compound_trans_order-fix.patch):
=====
Subject: thp: memcg: remove unnecessary compound_trans_order
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
In these places PageTransHuge must not go away under memcg, as the page is
owned by the thread handling it. Add VM_BUG_ON and remove a superflous
page_size variable.
compound_trans_order for now remains for memory-failure.c, which later has to
be fixed to implement a safe compound_head too, that isn't safe right now.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1027,10 +1027,6 @@ mem_cgroup_get_reclaim_stat_from_page(st
{
struct page_cgroup *pc;
struct mem_cgroup_per_zone *mz;
- int page_size = PAGE_SIZE;
-
- if (PageTransHuge(page))
- page_size <<= compound_trans_order(page);
if (mem_cgroup_disabled())
return NULL;
@@ -2287,8 +2283,10 @@ static int mem_cgroup_charge_common(stru
int ret;
int page_size = PAGE_SIZE;
- if (PageTransHuge(page))
- page_size <<= compound_trans_order(page);
+ if (PageTransHuge(page)) {
+ page_size <<= compound_order(page);
+ VM_BUG_ON(!PageTransHuge(page));
+ }
pc = lookup_page_cgroup(page);
/* can happen at boot */
@@ -2559,8 +2557,10 @@ __mem_cgroup_uncharge_common(struct page
if (PageSwapCache(page))
return NULL;
- if (PageTransHuge(page))
- page_size <<= compound_trans_order(page);
+ if (PageTransHuge(page)) {
+ page_size <<= compound_order(page);
+ VM_BUG_ON(!PageTransHuge(page));
+ }
count = page_size >> PAGE_SHIFT;
/*
On Wed, Dec 15, 2010 at 03:58:21PM -0800, Andrew Morton wrote:
>
> The patch titled
> thp: compound_trans_order
> has been added to the -mm tree. Its filename is
> thp-compound_trans_order.patch
>
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