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SubjectRe: [BUGFIX][PATCH 3/4] mecg: fix oom flag at THP charge
On Fri, 28 Jan 2011 09:02:13 +0100
Johannes Weiner <hannes@cmpxchg.org> wrote:

> On Fri, Jan 28, 2011 at 12:27:29PM +0900, KAMEZAWA Hiroyuki wrote:
> >
> > Thanks to Johanns and Daisuke for suggestion.
> > =
> > Hugepage allocation shouldn't trigger oom.
> > Allocation failure is not fatal.
> >
> > Orignal-patch-by: Johannes Weiner <hannes@cmpxchg.org>
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > ---
> > mm/memcontrol.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > Index: mmotm-0125/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-0125.orig/mm/memcontrol.c
> > +++ mmotm-0125/mm/memcontrol.c
> > @@ -2369,11 +2369,14 @@ static int mem_cgroup_charge_common(stru
> > struct page_cgroup *pc;
> > int ret;
> > int page_size = PAGE_SIZE;
> > + bool oom;
> >
> > if (PageTransHuge(page)) {
> > page_size <<= compound_order(page);
> > VM_BUG_ON(!PageTransHuge(page));
> > - }
> > + oom = false;
> > + } else
> > + oom = true;
>
> That needs a comment. You can take the one from my patch if you like.
>

How about this ?
==
Hugepage allocation shouldn't trigger oom.
Allocation failure is not fatal.

Changelog:
- added comments.

Orignal-patch-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
mm/memcontrol.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

Index: mmotm-0125/mm/memcontrol.c
===================================================================
--- mmotm-0125.orig/mm/memcontrol.c
+++ mmotm-0125/mm/memcontrol.c
@@ -2366,11 +2366,18 @@ static int mem_cgroup_charge_common(stru
struct page_cgroup *pc;
int ret;
int page_size = PAGE_SIZE;
+ bool oom;

if (PageTransHuge(page)) {
page_size <<= compound_order(page);
VM_BUG_ON(!PageTransHuge(page));
- }
+ /*
+ * Hugepage allocation will retry in small pages even if
+ * this allocation fails.
+ */
+ oom = false;
+ } else
+ oom = true;

pc = lookup_page_cgroup(page);
/* can happen at boot */
@@ -2378,7 +2385,7 @@ static int mem_cgroup_charge_common(stru
return 0;
prefetchw(pc);

- ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page_size);
+ ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
if (ret || !mem)
return ret;



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